Contact Dermatitis

Giant hogweed (Heracleum mantegazzianum) is an invasive flowering weed of the family Apiaceae that typically reaches a height of 13 feet, with thick stems; large green leaves; and umbrella-shaped, flat-topped, radial clusters (umbels) of small individual white flowers¹ (Figure 1). Because of the size and beauty of giant hogweed, it was widely planted in 19th century ornamental gardens in the United Kingdom and has since naturalized and spread throughout central Europe, Canada, and the United States.^1,2 The plant most commonly is found in shady areas near rivers and woodlands.¹

Due to the invasive nature of the giant hogweed, its prevalence continues to grow, its eradication remains difficult, and reports of phytophotodermatitis are increasing in number and distribution. In fact, there has been widespread media coverage of the dangers of giant hogweed in the United Kingdom since 2016¹ and in the United States in 2018 and 2019.^3-6

Transmission

Phytophotodermatitis is a type of nonimmunologic dermatitis caused by UV light reacting with a plant-based photosensitizing agent. In the case of giant hogweed, sap from the plant’s fruits, leaves, and stem contain furocoumarins or psoralens.⁷ Upon activation by UVA radiation, furan rings of these compounds create reactive oxygen species and intercalate with DNA pyrimidine bases, which results in cellular death, damage to successive skin layers, and reduced wound healing at the cellular level.⁸ This effect is intensified with increased percutaneous absorption of furocoumarin, which can result from high temperature, humidity, skin infection, lack of protective clothing, and moist conditions.⁹

The highest concentration of phototoxic compounds is found in giant hogweed from June through August,⁷ which, in combination with people increasing their outdoor activity in the summer, results in a greater prevalence and severity of H mantegazzianum phytophotodermatitis during summer months.

Presentation

Phytophotodermatitis caused by giant hogweed can range from burning and erythema to full-thickness chemical burns that require surgical debridement and skin grafting.⁸ After exposure to the offending agent, a harmful skin reaction can start within 15 minutes. After a latent period of approximately 24 hours, erythema, edema, and bullae can appear and generally peak by 72 hours.¹⁰ In addition to cutaneous injury, inhalation of giant hogweed traces can result in obstructive pulmonary symptoms. Eye contact can result in blindness.⁹

In addition to the rash caused by giant hogweed, a “weed-wacker dermatitis” or “strimmer rash” can be caused by the similar-appearing but smaller common hogweed (Heracleum sphondylium). Common hogweed is highly prevalent in the United States and often is confused with the larger giant hogweed because of tall stems and white, flat-topped flowers.

Management

Following contact with giant hogweed, a person should immediately avoid UV exposure and rinse the area with soap and water. UV radiation must be avoided for at least 48 hours. If erythema occurs, a topical steroid can be applied to the affected area; pain can be alleviated by a nonsteroidal anti-inflammatory drug.⁹

Further treatment might be required if bullous lesions are present. Small blisters can be punctured and drained; however, large blisters, extensive epidermal-dermal separation, and large areas of detached epidermis should simply be cleansed and dressed. An oral steroid also can be used to reduce inflammation in moderate and severe cases. Full-thickness injury might require surgical intervention.⁸

Clinical Case

A 27-year-old male landscaper presented to the emergency department with an increasingly painful blistering rash on the arms and neck of 1 day’s duration. He noticed bright red skin and blisters 18 to 24 hours after trimming what he identified as shoulder-high giant hogweed plants. Neither he nor his coworkers were wearing sunscreen or protective clothing as they cleared the plants for several hours. His coworkers developed similar rashes, but his rash was the most severe, requiring treatment in the emergency department.

Physical examination showed innumerable 2- to 10-mm, tense vesicles and bullae on a background of blanching erythema in a striking photodistribution along the neck (Figure 2) and arms (Figure 3). He had notable edema of both arms and several large 3- to 4-cm bullae on the ventral aspects of the forearms.

The patient was diagnosed with severe phytophotodermatitis secondary to contact with H mantegazzianum and was started on oral prednisone 70 mg daily (1 mg/kg/d), which was decreased by 10 mg every 3 days until the course of treatment was complete. He also was instructed to apply mupirocin ointment to open areas and petroleum jelly to intact skin. Additionally, he was advised to practice strict photoprotection for the near and distant future.

Within several days after treatment began, the phytophotodermatitis dramatically improved, with complete resolution in 1 week. Postinflammatory hyperpigmentation resolved after several weeks.

Giant hogweed (Heracleum mantegazzianum) is an invasive flowering weed of the family Apiaceae that typically reaches a height of 13 feet, with thick stems; large green leaves; and umbrella-shaped, flat-topped, radial clusters (umbels) of small individual white flowers¹ (Figure 1). Because of the size and beauty of giant hogweed, it was widely planted in 19th century ornamental gardens in the United Kingdom and has since naturalized and spread throughout central Europe, Canada, and the United States.^1,2 The plant most commonly is found in shady areas near rivers and woodlands.¹

Due to the invasive nature of the giant hogweed, its prevalence continues to grow, its eradication remains difficult, and reports of phytophotodermatitis are increasing in number and distribution. In fact, there has been widespread media coverage of the dangers of giant hogweed in the United Kingdom since 2016¹ and in the United States in 2018 and 2019.^3-6

Transmission

Phytophotodermatitis is a type of nonimmunologic dermatitis caused by UV light reacting with a plant-based photosensitizing agent. In the case of giant hogweed, sap from the plant’s fruits, leaves, and stem contain furocoumarins or psoralens.⁷ Upon activation by UVA radiation, furan rings of these compounds create reactive oxygen species and intercalate with DNA pyrimidine bases, which results in cellular death, damage to successive skin layers, and reduced wound healing at the cellular level.⁸ This effect is intensified with increased percutaneous absorption of furocoumarin, which can result from high temperature, humidity, skin infection, lack of protective clothing, and moist conditions.⁹

The highest concentration of phototoxic compounds is found in giant hogweed from June through August,⁷ which, in combination with people increasing their outdoor activity in the summer, results in a greater prevalence and severity of H mantegazzianum phytophotodermatitis during summer months.

Presentation

Phytophotodermatitis caused by giant hogweed can range from burning and erythema to full-thickness chemical burns that require surgical debridement and skin grafting.⁸ After exposure to the offending agent, a harmful skin reaction can start within 15 minutes. After a latent period of approximately 24 hours, erythema, edema, and bullae can appear and generally peak by 72 hours.¹⁰ In addition to cutaneous injury, inhalation of giant hogweed traces can result in obstructive pulmonary symptoms. Eye contact can result in blindness.⁹

In addition to the rash caused by giant hogweed, a “weed-wacker dermatitis” or “strimmer rash” can be caused by the similar-appearing but smaller common hogweed (Heracleum sphondylium). Common hogweed is highly prevalent in the United States and often is confused with the larger giant hogweed because of tall stems and white, flat-topped flowers.

Management

Following contact with giant hogweed, a person should immediately avoid UV exposure and rinse the area with soap and water. UV radiation must be avoided for at least 48 hours. If erythema occurs, a topical steroid can be applied to the affected area; pain can be alleviated by a nonsteroidal anti-inflammatory drug.⁹

Further treatment might be required if bullous lesions are present. Small blisters can be punctured and drained; however, large blisters, extensive epidermal-dermal separation, and large areas of detached epidermis should simply be cleansed and dressed. An oral steroid also can be used to reduce inflammation in moderate and severe cases. Full-thickness injury might require surgical intervention.⁸

Clinical Case

A 27-year-old male landscaper presented to the emergency department with an increasingly painful blistering rash on the arms and neck of 1 day’s duration. He noticed bright red skin and blisters 18 to 24 hours after trimming what he identified as shoulder-high giant hogweed plants. Neither he nor his coworkers were wearing sunscreen or protective clothing as they cleared the plants for several hours. His coworkers developed similar rashes, but his rash was the most severe, requiring treatment in the emergency department.

Physical examination showed innumerable 2- to 10-mm, tense vesicles and bullae on a background of blanching erythema in a striking photodistribution along the neck (Figure 2) and arms (Figure 3). He had notable edema of both arms and several large 3- to 4-cm bullae on the ventral aspects of the forearms.

The patient was diagnosed with severe phytophotodermatitis secondary to contact with H mantegazzianum and was started on oral prednisone 70 mg daily (1 mg/kg/d), which was decreased by 10 mg every 3 days until the course of treatment was complete. He also was instructed to apply mupirocin ointment to open areas and petroleum jelly to intact skin. Additionally, he was advised to practice strict photoprotection for the near and distant future.

Within several days after treatment began, the phytophotodermatitis dramatically improved, with complete resolution in 1 week. Postinflammatory hyperpigmentation resolved after several weeks.

Giant hogweed (Heracleum mantegazzianum) is an invasive flowering weed of the family Apiaceae that typically reaches a height of 13 feet, with thick stems; large green leaves; and umbrella-shaped, flat-topped, radial clusters (umbels) of small individual white flowers¹ (Figure 1). Because of the size and beauty of giant hogweed, it was widely planted in 19th century ornamental gardens in the United Kingdom and has since naturalized and spread throughout central Europe, Canada, and the United States.^1,2 The plant most commonly is found in shady areas near rivers and woodlands.¹

Due to the invasive nature of the giant hogweed, its prevalence continues to grow, its eradication remains difficult, and reports of phytophotodermatitis are increasing in number and distribution. In fact, there has been widespread media coverage of the dangers of giant hogweed in the United Kingdom since 2016¹ and in the United States in 2018 and 2019.^3-6

Transmission

Phytophotodermatitis is a type of nonimmunologic dermatitis caused by UV light reacting with a plant-based photosensitizing agent. In the case of giant hogweed, sap from the plant’s fruits, leaves, and stem contain furocoumarins or psoralens.⁷ Upon activation by UVA radiation, furan rings of these compounds create reactive oxygen species and intercalate with DNA pyrimidine bases, which results in cellular death, damage to successive skin layers, and reduced wound healing at the cellular level.⁸ This effect is intensified with increased percutaneous absorption of furocoumarin, which can result from high temperature, humidity, skin infection, lack of protective clothing, and moist conditions.⁹

The highest concentration of phototoxic compounds is found in giant hogweed from June through August,⁷ which, in combination with people increasing their outdoor activity in the summer, results in a greater prevalence and severity of H mantegazzianum phytophotodermatitis during summer months.

Presentation

Phytophotodermatitis caused by giant hogweed can range from burning and erythema to full-thickness chemical burns that require surgical debridement and skin grafting.⁸ After exposure to the offending agent, a harmful skin reaction can start within 15 minutes. After a latent period of approximately 24 hours, erythema, edema, and bullae can appear and generally peak by 72 hours.¹⁰ In addition to cutaneous injury, inhalation of giant hogweed traces can result in obstructive pulmonary symptoms. Eye contact can result in blindness.⁹

In addition to the rash caused by giant hogweed, a “weed-wacker dermatitis” or “strimmer rash” can be caused by the similar-appearing but smaller common hogweed (Heracleum sphondylium). Common hogweed is highly prevalent in the United States and often is confused with the larger giant hogweed because of tall stems and white, flat-topped flowers.

Management

Following contact with giant hogweed, a person should immediately avoid UV exposure and rinse the area with soap and water. UV radiation must be avoided for at least 48 hours. If erythema occurs, a topical steroid can be applied to the affected area; pain can be alleviated by a nonsteroidal anti-inflammatory drug.⁹

Further treatment might be required if bullous lesions are present. Small blisters can be punctured and drained; however, large blisters, extensive epidermal-dermal separation, and large areas of detached epidermis should simply be cleansed and dressed. An oral steroid also can be used to reduce inflammation in moderate and severe cases. Full-thickness injury might require surgical intervention.⁸

Clinical Case

A 27-year-old male landscaper presented to the emergency department with an increasingly painful blistering rash on the arms and neck of 1 day’s duration. He noticed bright red skin and blisters 18 to 24 hours after trimming what he identified as shoulder-high giant hogweed plants. Neither he nor his coworkers were wearing sunscreen or protective clothing as they cleared the plants for several hours. His coworkers developed similar rashes, but his rash was the most severe, requiring treatment in the emergency department.

Physical examination showed innumerable 2- to 10-mm, tense vesicles and bullae on a background of blanching erythema in a striking photodistribution along the neck (Figure 2) and arms (Figure 3). He had notable edema of both arms and several large 3- to 4-cm bullae on the ventral aspects of the forearms.

The patient was diagnosed with severe phytophotodermatitis secondary to contact with H mantegazzianum and was started on oral prednisone 70 mg daily (1 mg/kg/d), which was decreased by 10 mg every 3 days until the course of treatment was complete. He also was instructed to apply mupirocin ointment to open areas and petroleum jelly to intact skin. Additionally, he was advised to practice strict photoprotection for the near and distant future.

Within several days after treatment began, the phytophotodermatitis dramatically improved, with complete resolution in 1 week. Postinflammatory hyperpigmentation resolved after several weeks.

To the Editor:

Pityriasis rubra pilaris (PRP) is a rare inflammatory dermatosis of unknown etiology characterized by erythematosquamous salmon-colored plaques with well-demarcated islands of unaffected skin and hyperkeratotic follicles.¹ In the United States, an incidence of 1 in 3500to 5000 patients presenting to dermatology clinics has been reported.² Pityriasis rubra pilaris has several subtypes and variability in presentation that can make accurate and timely diagnosis challenging.^3-5 Herein, we present a case of PRP with complex diagnostic and therapeutic challenges.

A 22-year-old woman presented with symmetrical, well-demarcated, hyperkeratotic, erythematous plaques with a carnauba wax–like appearance on the palms (Figure 1), soles, elbows, and trunk covering approximately 5% of the body surface area. Two weeks prior to presentation, she experienced an upper respiratory tract infection without any treatment and subsequently developed redness on the palms, which became very hard and scaly. The redness then spread to the elbows, soles, and trunk. She reported itching as well as pain in areas of fissuring. Hand mobility became restricted due to thick scale.

The patient’s medical history was notable for suspected psoriasis 9 years prior, but there were no records or biopsy reports that could be obtained to confirm the diagnosis. She also reported a similar skin condition in her father, which also was diagnosed as psoriasis, but this diagnosis could not be verified.

Although the morphology of the lesions was most consistent with localized PRP, atypical psoriasis, palmoplantar keratoderma (PPK), and erythroderma progressive symmetrica (EPS) also were considered given the personal and family history of suspected psoriasis. A biopsy could not be obtained due to an insurance issue. She was started on clobetasol cream 0.05% and ointment. At 2-week follow-up, her condition remained unchanged. Empiric systemic treatment was discussed, which would potentially work for diagnoses of both PRP and psoriasis. Due to the history of psoriasis and level of discomfort, cyclosporine 300 mg once daily was started to gain rapid control of the disease. Methotrexate also was considered due to its efficacy and economic considerations but was not selected due to patient concerns about the medication.

After 10 weeks of cyclosporine treatment, our patient showed some improvement of the skin with decreased scale and flattening of plaques but not complete resolution. At this point, a biopsy was able to be obtained with prior authorization. A 4-mm punch biopsy of the right flank demonstrated a psoriasiform and papillated epidermis with multifocally capped, compact parakeratosis and minimal lymphocytic infiltrate consistent with PRP. Although EPS also was on the histologic differential, clinical history was more consistent with a diagnosis of PRP. There was some minimal improvement with cyclosporine, but with the diagnosis of PRP confirmed, a systemic retinoid became the treatment of choice. Although acitretin is the preferred treatment for PRP, given that pregnancy would be contraindicated during and for 3 years following acitretin therapy, a trial of isotretinoin 40 mg once daily was started due to its shorter half-life compared to acitretin and was continued for 3 months (Figure 2).^6,7

The diagnosis of PRP often can be challenging given the variety of clinical presentations. This case was an atypical presentation of PRP with several learning points, as our patient’s condition did not fit perfectly into any of the 6 types of PRP. The age of onset was atypical at 22 years old. Pityriasis rubra pilaris typically presents with a bimodal age distribution, appearing either in the first decade or the fifth to sixth decades of life.^3,8 Her clinical presentation was atypical for adult-onset types I and II, which typically present with cephalocaudal progression or ichthyosiform dermatitis, respectively. Her presentation also was atypical for juvenile onset in types III, IV, and V, which tend to present in younger children and with different physical examination findings.^3,8

The morphology of our patient’s lesions also was atypical for PRP, PPK, EPS, and psoriasis. The clinical presentation had features of these entities with erythema, fissuring, xerosis, carnauba wax–like appearance, symmetric scale, and well-demarcated plaques. Although these findings are not mutually exclusive, their combined presentation is atypical. Coupled with the ambiguous family history of similar skin disease in the patient’s father, the discussion of genodermatoses, particularly PPK, further confounded the diagnosis.^4,9 When evaluating for PRP, especially with any family history of skin conditions, genodermatoses should be considered. Furthermore, our patient’s remote and unverifiable history of psoriasis serves as a cautionary reminder that prior diagnoses and medical history always should be reasonably scrutinized. Additionally, a drug-induced PRP eruption also should be considered. Although our patient received no medical treatment for the upper respiratory tract infection prior to the onset of PRP, there have been several reports of drug-induced PRP.^10-12

The therapeutic challenge in this case is one that often is encountered in clinical practice. The health care system often may pose a barrier to diagnosis by inhibiting particular services required for adequate patient care. For our patient, diagnosis was delayed by several weeks due to difficulties obtaining a diagnostic skin biopsy. When faced with challenges from health care infrastructure, creativity with treatment options, such as finding an empiric treatment option (cyclosporine in this case), must be considered.

Systemic retinoids have been found to be efficacious treatment options for PRP, but when dealing with a woman of reproductive age, reproductive preferences must be discussed before identifying an appropriate treatment regimen.^1,13-15 The half-life of acitretin compared to isotretinoin is 2 days vs 22 hours.^6,16 With alcohol consumption, acitretin can be metabolized to etretinate, which has a half-life of 120 days.¹⁷ In our patient, isotretinoin was a more manageable option to allow for greater reproductive freedom upon treatment completion.

To the Editor:

Pityriasis rubra pilaris (PRP) is a rare inflammatory dermatosis of unknown etiology characterized by erythematosquamous salmon-colored plaques with well-demarcated islands of unaffected skin and hyperkeratotic follicles.¹ In the United States, an incidence of 1 in 3500to 5000 patients presenting to dermatology clinics has been reported.² Pityriasis rubra pilaris has several subtypes and variability in presentation that can make accurate and timely diagnosis challenging.^3-5 Herein, we present a case of PRP with complex diagnostic and therapeutic challenges.

A 22-year-old woman presented with symmetrical, well-demarcated, hyperkeratotic, erythematous plaques with a carnauba wax–like appearance on the palms (Figure 1), soles, elbows, and trunk covering approximately 5% of the body surface area. Two weeks prior to presentation, she experienced an upper respiratory tract infection without any treatment and subsequently developed redness on the palms, which became very hard and scaly. The redness then spread to the elbows, soles, and trunk. She reported itching as well as pain in areas of fissuring. Hand mobility became restricted due to thick scale.

The patient’s medical history was notable for suspected psoriasis 9 years prior, but there were no records or biopsy reports that could be obtained to confirm the diagnosis. She also reported a similar skin condition in her father, which also was diagnosed as psoriasis, but this diagnosis could not be verified.

Although the morphology of the lesions was most consistent with localized PRP, atypical psoriasis, palmoplantar keratoderma (PPK), and erythroderma progressive symmetrica (EPS) also were considered given the personal and family history of suspected psoriasis. A biopsy could not be obtained due to an insurance issue. She was started on clobetasol cream 0.05% and ointment. At 2-week follow-up, her condition remained unchanged. Empiric systemic treatment was discussed, which would potentially work for diagnoses of both PRP and psoriasis. Due to the history of psoriasis and level of discomfort, cyclosporine 300 mg once daily was started to gain rapid control of the disease. Methotrexate also was considered due to its efficacy and economic considerations but was not selected due to patient concerns about the medication.

After 10 weeks of cyclosporine treatment, our patient showed some improvement of the skin with decreased scale and flattening of plaques but not complete resolution. At this point, a biopsy was able to be obtained with prior authorization. A 4-mm punch biopsy of the right flank demonstrated a psoriasiform and papillated epidermis with multifocally capped, compact parakeratosis and minimal lymphocytic infiltrate consistent with PRP. Although EPS also was on the histologic differential, clinical history was more consistent with a diagnosis of PRP. There was some minimal improvement with cyclosporine, but with the diagnosis of PRP confirmed, a systemic retinoid became the treatment of choice. Although acitretin is the preferred treatment for PRP, given that pregnancy would be contraindicated during and for 3 years following acitretin therapy, a trial of isotretinoin 40 mg once daily was started due to its shorter half-life compared to acitretin and was continued for 3 months (Figure 2).^6,7

The diagnosis of PRP often can be challenging given the variety of clinical presentations. This case was an atypical presentation of PRP with several learning points, as our patient’s condition did not fit perfectly into any of the 6 types of PRP. The age of onset was atypical at 22 years old. Pityriasis rubra pilaris typically presents with a bimodal age distribution, appearing either in the first decade or the fifth to sixth decades of life.^3,8 Her clinical presentation was atypical for adult-onset types I and II, which typically present with cephalocaudal progression or ichthyosiform dermatitis, respectively. Her presentation also was atypical for juvenile onset in types III, IV, and V, which tend to present in younger children and with different physical examination findings.^3,8

The morphology of our patient’s lesions also was atypical for PRP, PPK, EPS, and psoriasis. The clinical presentation had features of these entities with erythema, fissuring, xerosis, carnauba wax–like appearance, symmetric scale, and well-demarcated plaques. Although these findings are not mutually exclusive, their combined presentation is atypical. Coupled with the ambiguous family history of similar skin disease in the patient’s father, the discussion of genodermatoses, particularly PPK, further confounded the diagnosis.^4,9 When evaluating for PRP, especially with any family history of skin conditions, genodermatoses should be considered. Furthermore, our patient’s remote and unverifiable history of psoriasis serves as a cautionary reminder that prior diagnoses and medical history always should be reasonably scrutinized. Additionally, a drug-induced PRP eruption also should be considered. Although our patient received no medical treatment for the upper respiratory tract infection prior to the onset of PRP, there have been several reports of drug-induced PRP.^10-12

The therapeutic challenge in this case is one that often is encountered in clinical practice. The health care system often may pose a barrier to diagnosis by inhibiting particular services required for adequate patient care. For our patient, diagnosis was delayed by several weeks due to difficulties obtaining a diagnostic skin biopsy. When faced with challenges from health care infrastructure, creativity with treatment options, such as finding an empiric treatment option (cyclosporine in this case), must be considered.

Systemic retinoids have been found to be efficacious treatment options for PRP, but when dealing with a woman of reproductive age, reproductive preferences must be discussed before identifying an appropriate treatment regimen.^1,13-15 The half-life of acitretin compared to isotretinoin is 2 days vs 22 hours.^6,16 With alcohol consumption, acitretin can be metabolized to etretinate, which has a half-life of 120 days.¹⁷ In our patient, isotretinoin was a more manageable option to allow for greater reproductive freedom upon treatment completion.

To the Editor:

Pityriasis rubra pilaris (PRP) is a rare inflammatory dermatosis of unknown etiology characterized by erythematosquamous salmon-colored plaques with well-demarcated islands of unaffected skin and hyperkeratotic follicles.¹ In the United States, an incidence of 1 in 3500to 5000 patients presenting to dermatology clinics has been reported.² Pityriasis rubra pilaris has several subtypes and variability in presentation that can make accurate and timely diagnosis challenging.^3-5 Herein, we present a case of PRP with complex diagnostic and therapeutic challenges.

A 22-year-old woman presented with symmetrical, well-demarcated, hyperkeratotic, erythematous plaques with a carnauba wax–like appearance on the palms (Figure 1), soles, elbows, and trunk covering approximately 5% of the body surface area. Two weeks prior to presentation, she experienced an upper respiratory tract infection without any treatment and subsequently developed redness on the palms, which became very hard and scaly. The redness then spread to the elbows, soles, and trunk. She reported itching as well as pain in areas of fissuring. Hand mobility became restricted due to thick scale.

The patient’s medical history was notable for suspected psoriasis 9 years prior, but there were no records or biopsy reports that could be obtained to confirm the diagnosis. She also reported a similar skin condition in her father, which also was diagnosed as psoriasis, but this diagnosis could not be verified.

Although the morphology of the lesions was most consistent with localized PRP, atypical psoriasis, palmoplantar keratoderma (PPK), and erythroderma progressive symmetrica (EPS) also were considered given the personal and family history of suspected psoriasis. A biopsy could not be obtained due to an insurance issue. She was started on clobetasol cream 0.05% and ointment. At 2-week follow-up, her condition remained unchanged. Empiric systemic treatment was discussed, which would potentially work for diagnoses of both PRP and psoriasis. Due to the history of psoriasis and level of discomfort, cyclosporine 300 mg once daily was started to gain rapid control of the disease. Methotrexate also was considered due to its efficacy and economic considerations but was not selected due to patient concerns about the medication.

After 10 weeks of cyclosporine treatment, our patient showed some improvement of the skin with decreased scale and flattening of plaques but not complete resolution. At this point, a biopsy was able to be obtained with prior authorization. A 4-mm punch biopsy of the right flank demonstrated a psoriasiform and papillated epidermis with multifocally capped, compact parakeratosis and minimal lymphocytic infiltrate consistent with PRP. Although EPS also was on the histologic differential, clinical history was more consistent with a diagnosis of PRP. There was some minimal improvement with cyclosporine, but with the diagnosis of PRP confirmed, a systemic retinoid became the treatment of choice. Although acitretin is the preferred treatment for PRP, given that pregnancy would be contraindicated during and for 3 years following acitretin therapy, a trial of isotretinoin 40 mg once daily was started due to its shorter half-life compared to acitretin and was continued for 3 months (Figure 2).^6,7

The diagnosis of PRP often can be challenging given the variety of clinical presentations. This case was an atypical presentation of PRP with several learning points, as our patient’s condition did not fit perfectly into any of the 6 types of PRP. The age of onset was atypical at 22 years old. Pityriasis rubra pilaris typically presents with a bimodal age distribution, appearing either in the first decade or the fifth to sixth decades of life.^3,8 Her clinical presentation was atypical for adult-onset types I and II, which typically present with cephalocaudal progression or ichthyosiform dermatitis, respectively. Her presentation also was atypical for juvenile onset in types III, IV, and V, which tend to present in younger children and with different physical examination findings.^3,8

The morphology of our patient’s lesions also was atypical for PRP, PPK, EPS, and psoriasis. The clinical presentation had features of these entities with erythema, fissuring, xerosis, carnauba wax–like appearance, symmetric scale, and well-demarcated plaques. Although these findings are not mutually exclusive, their combined presentation is atypical. Coupled with the ambiguous family history of similar skin disease in the patient’s father, the discussion of genodermatoses, particularly PPK, further confounded the diagnosis.^4,9 When evaluating for PRP, especially with any family history of skin conditions, genodermatoses should be considered. Furthermore, our patient’s remote and unverifiable history of psoriasis serves as a cautionary reminder that prior diagnoses and medical history always should be reasonably scrutinized. Additionally, a drug-induced PRP eruption also should be considered. Although our patient received no medical treatment for the upper respiratory tract infection prior to the onset of PRP, there have been several reports of drug-induced PRP.^10-12

The therapeutic challenge in this case is one that often is encountered in clinical practice. The health care system often may pose a barrier to diagnosis by inhibiting particular services required for adequate patient care. For our patient, diagnosis was delayed by several weeks due to difficulties obtaining a diagnostic skin biopsy. When faced with challenges from health care infrastructure, creativity with treatment options, such as finding an empiric treatment option (cyclosporine in this case), must be considered.

Systemic retinoids have been found to be efficacious treatment options for PRP, but when dealing with a woman of reproductive age, reproductive preferences must be discussed before identifying an appropriate treatment regimen.^1,13-15 The half-life of acitretin compared to isotretinoin is 2 days vs 22 hours.^6,16 With alcohol consumption, acitretin can be metabolized to etretinate, which has a half-life of 120 days.¹⁷ In our patient, isotretinoin was a more manageable option to allow for greater reproductive freedom upon treatment completion.

With the strong likelihood that dermatologists in the United States will have to resolve dermatologic issues created by cultural cosmetic practices originating elsewhere, strategies for an open nonjudgmental approach are instrumental, according to a dermatologist with expertise in these types of cases who spoke at the Skin of Color Update 2021.

“Instead of avoiding the discussion of cultural practices, we should discuss them and be open about them. It fosters a comfortable environment, trust, and better compliance,” reported Neelam Ajit Vashi, MD, founding director of the Boston University Center for Ethnic Skin.

Out of fear of causing offense, a desire to be discreet, or of personal discomfort with foreign cultural practices, some clinicians might elect to limit themselves to the information that the patient volunteers, which is a mistake, according to Dr. Vashi.

“The avoidance of topics around culture actually limits the ability to have a successful relationship,” she maintained.

Successful encounters are not just based on a willingness to listen, Dr. Vashi said. Clinicians should be seeking a base of knowledge. With growing globalization and widespread immigration, “it is increasingly important for dermatologists in the U.S. to understand the role of cultural practices [in creating skin problems] and recognize the sequelae,” Dr. Vashi said.

Taking some common examples of dermatologic complaints created by cosmetic practices originating elsewhere, Dr. Vashi described key clinical points in addressing complications related to henna, hair removal through threading, and placement of decorative adornments on the forehead, called bindi. In addition, she pointed out common issues with facial and body marking created with kumkum powder, hair oils, and skin lightening agents.
 

Black henna

For cosmetic enhancement, henna is relatively benign. It is also no longer confined to the south Asian communities where it originated. However, Dr. Vashi pointed out that patients of south Asian origin or descent might be more likely to use black henna, a variety with more risks.

Black henna contains additives, such as diaminobenzenes and p-phenylenediamine (PPD), to darken the tone of the product as well as provide other desired characteristics, such as an accelerated drying time. While some patients do develop reactions to conventional henna, the risks of black henna are greater.

“The acute contact dermatitis reactions can include dyspigmentation, leukoderma, and keloids,” Dr. Vashi said. Other complications include erythema multiforme, temporary hypertrichosis, and systemic allergic reactions, such as angioedema.

While those who have had a reaction to henna should avoid further contact, Dr. Vashi warned that sequelae can include cross reactions with latex and rubber as well as some pharmaceutical agents, such as sulfonamides. When taking a patient history, she noted, be aware that risks of henna extend to the hairdressers and cosmeticians who sometimes apply these products on others.

Hair threading, bindi, and kumkum

Hair threading, another practice popularized in south Asia and now growing in popularity globally, involves capturing hairs between cotton threads for removal of both the hair and its follicle. It is a relatively rapid and efficient method of permanent depilation. In addition to pain and erythema, Dr. Vashi reported that the complications associated with hair threading include pigmentary changes, infections such as bullous impetigo, and lesions of koebnerization – such as vitiligo and lichen planus.

Bindi, a Hindi tradition that involves placing adornments between the eyebrows, and kumkum, a powder typically made from turmeric to be employed for decorative markings, have also spread to use outside of their cultural context, according to Dr. Vashi. She said that the complications of these two cosmetic practices are shared, and stem largely from contact dermatitis.

Veena Nair/Moment/Getty Images

Hair oils, skin-lightening agents

Culturally-linked hair oils among patients from south Asia or Africa – or descendants from these areas – can damage hair in a variety of ways as well as cause contact dermatitis. The oils can also exacerbate existing skin diseases.

“Oils with high oleic acid, such as coconut or olive oils or shea butter, can worsen seborrheic dermatitis,” Dr. Vashi cautioned.

Of this list of dermatologic issues induced by culturally linked cosmetic practices, skin lightening agents might pose the most risk for permanent and irreversible complications. Dr. Vashi said that up to 70% of patients using lighteners develop complications, and there is a relationship between the severity of side effects as duration of use increases.

“The problem is that ingredients of many of these products, which are imported illegally and sold on the black market, are often not disclosed,” Dr. Vashi said. Some contain a high content of metals such as lead, copper, and iron, whether they are added intentionally or end up in the product because of poor quality control. For those developing adverse events associated with the products, the obvious treatment is discontinuation.

When patients are unwilling to discontinue any of the products that have led to dermatologic issues, Dr. Vashi encouraged physicians “to take a middle ground.” Simple avoidance can be challenging for practices that are culturally meaningful. In respecting cultural differences, she encouraged tolerance and compromise.

“Often these patients will be doing an alternative medication or intervention, but this does not mean that they are not accepting what we have to offer,” she said. She indicated that mutual respect will lead to better solutions.

The awareness of common cultural practices that can have a harmful impact on the skin is an area of practice that deserves more attention, Andrew F. Alexis, MD, vice-chair for diversity and inclusion in the department of dermatology at Weill Cornell Medical Center, New York, said in an interview.

With the strong likelihood that dermatologists in the United States will have to resolve dermatologic issues created by cultural cosmetic practices originating elsewhere, strategies for an open nonjudgmental approach are instrumental, according to a dermatologist with expertise in these types of cases who spoke at the Skin of Color Update 2021.

“Instead of avoiding the discussion of cultural practices, we should discuss them and be open about them. It fosters a comfortable environment, trust, and better compliance,” reported Neelam Ajit Vashi, MD, founding director of the Boston University Center for Ethnic Skin.

Out of fear of causing offense, a desire to be discreet, or of personal discomfort with foreign cultural practices, some clinicians might elect to limit themselves to the information that the patient volunteers, which is a mistake, according to Dr. Vashi.

“The avoidance of topics around culture actually limits the ability to have a successful relationship,” she maintained.

Successful encounters are not just based on a willingness to listen, Dr. Vashi said. Clinicians should be seeking a base of knowledge. With growing globalization and widespread immigration, “it is increasingly important for dermatologists in the U.S. to understand the role of cultural practices [in creating skin problems] and recognize the sequelae,” Dr. Vashi said.

Taking some common examples of dermatologic complaints created by cosmetic practices originating elsewhere, Dr. Vashi described key clinical points in addressing complications related to henna, hair removal through threading, and placement of decorative adornments on the forehead, called bindi. In addition, she pointed out common issues with facial and body marking created with kumkum powder, hair oils, and skin lightening agents.
 

Black henna

For cosmetic enhancement, henna is relatively benign. It is also no longer confined to the south Asian communities where it originated. However, Dr. Vashi pointed out that patients of south Asian origin or descent might be more likely to use black henna, a variety with more risks.

Black henna contains additives, such as diaminobenzenes and p-phenylenediamine (PPD), to darken the tone of the product as well as provide other desired characteristics, such as an accelerated drying time. While some patients do develop reactions to conventional henna, the risks of black henna are greater.

“The acute contact dermatitis reactions can include dyspigmentation, leukoderma, and keloids,” Dr. Vashi said. Other complications include erythema multiforme, temporary hypertrichosis, and systemic allergic reactions, such as angioedema.

While those who have had a reaction to henna should avoid further contact, Dr. Vashi warned that sequelae can include cross reactions with latex and rubber as well as some pharmaceutical agents, such as sulfonamides. When taking a patient history, she noted, be aware that risks of henna extend to the hairdressers and cosmeticians who sometimes apply these products on others.

Hair threading, bindi, and kumkum

Hair threading, another practice popularized in south Asia and now growing in popularity globally, involves capturing hairs between cotton threads for removal of both the hair and its follicle. It is a relatively rapid and efficient method of permanent depilation. In addition to pain and erythema, Dr. Vashi reported that the complications associated with hair threading include pigmentary changes, infections such as bullous impetigo, and lesions of koebnerization – such as vitiligo and lichen planus.

Bindi, a Hindi tradition that involves placing adornments between the eyebrows, and kumkum, a powder typically made from turmeric to be employed for decorative markings, have also spread to use outside of their cultural context, according to Dr. Vashi. She said that the complications of these two cosmetic practices are shared, and stem largely from contact dermatitis.

Veena Nair/Moment/Getty Images

Hair oils, skin-lightening agents

Culturally-linked hair oils among patients from south Asia or Africa – or descendants from these areas – can damage hair in a variety of ways as well as cause contact dermatitis. The oils can also exacerbate existing skin diseases.

“Oils with high oleic acid, such as coconut or olive oils or shea butter, can worsen seborrheic dermatitis,” Dr. Vashi cautioned.

Of this list of dermatologic issues induced by culturally linked cosmetic practices, skin lightening agents might pose the most risk for permanent and irreversible complications. Dr. Vashi said that up to 70% of patients using lighteners develop complications, and there is a relationship between the severity of side effects as duration of use increases.

“The problem is that ingredients of many of these products, which are imported illegally and sold on the black market, are often not disclosed,” Dr. Vashi said. Some contain a high content of metals such as lead, copper, and iron, whether they are added intentionally or end up in the product because of poor quality control. For those developing adverse events associated with the products, the obvious treatment is discontinuation.

When patients are unwilling to discontinue any of the products that have led to dermatologic issues, Dr. Vashi encouraged physicians “to take a middle ground.” Simple avoidance can be challenging for practices that are culturally meaningful. In respecting cultural differences, she encouraged tolerance and compromise.

“Often these patients will be doing an alternative medication or intervention, but this does not mean that they are not accepting what we have to offer,” she said. She indicated that mutual respect will lead to better solutions.

The awareness of common cultural practices that can have a harmful impact on the skin is an area of practice that deserves more attention, Andrew F. Alexis, MD, vice-chair for diversity and inclusion in the department of dermatology at Weill Cornell Medical Center, New York, said in an interview.

With the strong likelihood that dermatologists in the United States will have to resolve dermatologic issues created by cultural cosmetic practices originating elsewhere, strategies for an open nonjudgmental approach are instrumental, according to a dermatologist with expertise in these types of cases who spoke at the Skin of Color Update 2021.

“Instead of avoiding the discussion of cultural practices, we should discuss them and be open about them. It fosters a comfortable environment, trust, and better compliance,” reported Neelam Ajit Vashi, MD, founding director of the Boston University Center for Ethnic Skin.

Out of fear of causing offense, a desire to be discreet, or of personal discomfort with foreign cultural practices, some clinicians might elect to limit themselves to the information that the patient volunteers, which is a mistake, according to Dr. Vashi.

“The avoidance of topics around culture actually limits the ability to have a successful relationship,” she maintained.

Successful encounters are not just based on a willingness to listen, Dr. Vashi said. Clinicians should be seeking a base of knowledge. With growing globalization and widespread immigration, “it is increasingly important for dermatologists in the U.S. to understand the role of cultural practices [in creating skin problems] and recognize the sequelae,” Dr. Vashi said.

Taking some common examples of dermatologic complaints created by cosmetic practices originating elsewhere, Dr. Vashi described key clinical points in addressing complications related to henna, hair removal through threading, and placement of decorative adornments on the forehead, called bindi. In addition, she pointed out common issues with facial and body marking created with kumkum powder, hair oils, and skin lightening agents.
 

Black henna

For cosmetic enhancement, henna is relatively benign. It is also no longer confined to the south Asian communities where it originated. However, Dr. Vashi pointed out that patients of south Asian origin or descent might be more likely to use black henna, a variety with more risks.

Black henna contains additives, such as diaminobenzenes and p-phenylenediamine (PPD), to darken the tone of the product as well as provide other desired characteristics, such as an accelerated drying time. While some patients do develop reactions to conventional henna, the risks of black henna are greater.

“The acute contact dermatitis reactions can include dyspigmentation, leukoderma, and keloids,” Dr. Vashi said. Other complications include erythema multiforme, temporary hypertrichosis, and systemic allergic reactions, such as angioedema.

While those who have had a reaction to henna should avoid further contact, Dr. Vashi warned that sequelae can include cross reactions with latex and rubber as well as some pharmaceutical agents, such as sulfonamides. When taking a patient history, she noted, be aware that risks of henna extend to the hairdressers and cosmeticians who sometimes apply these products on others.

Hair threading, bindi, and kumkum

Hair threading, another practice popularized in south Asia and now growing in popularity globally, involves capturing hairs between cotton threads for removal of both the hair and its follicle. It is a relatively rapid and efficient method of permanent depilation. In addition to pain and erythema, Dr. Vashi reported that the complications associated with hair threading include pigmentary changes, infections such as bullous impetigo, and lesions of koebnerization – such as vitiligo and lichen planus.

Bindi, a Hindi tradition that involves placing adornments between the eyebrows, and kumkum, a powder typically made from turmeric to be employed for decorative markings, have also spread to use outside of their cultural context, according to Dr. Vashi. She said that the complications of these two cosmetic practices are shared, and stem largely from contact dermatitis.

Veena Nair/Moment/Getty Images

Hair oils, skin-lightening agents

Culturally-linked hair oils among patients from south Asia or Africa – or descendants from these areas – can damage hair in a variety of ways as well as cause contact dermatitis. The oils can also exacerbate existing skin diseases.

“Oils with high oleic acid, such as coconut or olive oils or shea butter, can worsen seborrheic dermatitis,” Dr. Vashi cautioned.

Of this list of dermatologic issues induced by culturally linked cosmetic practices, skin lightening agents might pose the most risk for permanent and irreversible complications. Dr. Vashi said that up to 70% of patients using lighteners develop complications, and there is a relationship between the severity of side effects as duration of use increases.

“The problem is that ingredients of many of these products, which are imported illegally and sold on the black market, are often not disclosed,” Dr. Vashi said. Some contain a high content of metals such as lead, copper, and iron, whether they are added intentionally or end up in the product because of poor quality control. For those developing adverse events associated with the products, the obvious treatment is discontinuation.

When patients are unwilling to discontinue any of the products that have led to dermatologic issues, Dr. Vashi encouraged physicians “to take a middle ground.” Simple avoidance can be challenging for practices that are culturally meaningful. In respecting cultural differences, she encouraged tolerance and compromise.

“Often these patients will be doing an alternative medication or intervention, but this does not mean that they are not accepting what we have to offer,” she said. She indicated that mutual respect will lead to better solutions.

The awareness of common cultural practices that can have a harmful impact on the skin is an area of practice that deserves more attention, Andrew F. Alexis, MD, vice-chair for diversity and inclusion in the department of dermatology at Weill Cornell Medical Center, New York, said in an interview.

Dermatology is an often-underutilized resource in the hospital setting. As the health care landscape has evolved, so has the role of the inpatient dermatologist.^1-3 Structural changes in the health system and advances in therapies have shifted dermatology from an admitting service to an almost exclusively outpatient practice. Improved treatment modalities led to decreases in the number of patients requiring admission for chronic dermatoses, and outpatient clinics began offering therapies once limited to hospitals.^1,4 Inpatient dermatology consultations emerged and continue to have profound effects on hospitalized patients regardless of their reason for admission.^1-11

Inpatient dermatologists supply knowledge in areas primary medical teams lack, and there is evidence that dermatology consultations improve the quality of care while decreasing cost.^2,5-7 Establishing correct diagnoses, preventing exposure to unnecessary medications, and reducing hospitalization duration and readmission rates are a few ways dermatology consultations positively impact hospitalized patients.^2,5-7,9,10 This study highlights the role of the dermatologist in the care of hospitalized patients at a large academic medical center in an urban setting and reveals how consultation supports the efficiency and efficacy of other services.

Materials and Methods

Study Design—This single-institution, cross-sectional retrospective study included all hospitalized patients at the Thomas Jefferson University Hospital (Philadelphia, Pennsylvania), who received an inpatient dermatology consultation completed by physicians of Jefferson Dermatology Associates between January 1, 2019, and December 31, 2019. The institutional review board at Thomas Jefferson University approved this study.

Data Collection—A list of all inpatient dermatology consultations in 2019 was provided by Jefferson Dermatology Associates. Through a retrospective chart review, data regarding the consultations were collected from the electronic medical record (Epic Systems) and recorded into the Research Electronic Data Capture system. Data on patient demographics, the primary medical team, the dermatology evaluation, and the hospital course of the patient were collected.

Results

Patient Characteristics—Dermatology received 253 inpatient consultation requests during this time period; 53% of patients were female and 47% were male, with a mean age of 55 years. Most patients were White (57%), while 34% were Black. Five percent and 4% of patients were Asian and Hispanic or Latino, respectively (Table 1). The mean duration of hospitalization for all patients was 15 days, and the average number of days to discharge following the first encounter with dermatology was 10 days.

Requesting Team and Reason for Consultation—Internal medicine consulted dermatology most frequently (34% of all consultations), followed by emergency medicine (14%) and a variety of other services (Table 1). Most dermatology consultations were placed to assist in achieving a diagnosis of a cutaneous condition (77%), while a minority were to assist in the management of a previously diagnosed disease (22%). A small fraction of consultations (5%) were to complete full-body skin examinations (FBSEs) to rule out infection or malignancy in candidates for organ transplantation, left ventricular assist devices, or certain chemotherapies. One FBSE was conducted to search for a primary tumor in a patient diagnosed with metastatic melanoma.

Most Common Final Diagnoses and Consultation Impact—Table 2 lists the most common final diagnosis categories, as well as the effects of the consultation on diagnosis, management, biopsies, hospitalization, and clinical improvement as documented by the primary medical provider. The most common final diagnoses were inflammatory and autoimmune (39%), such as contact dermatitis and seborrheic dermatitis; infectious (23%), such as varicella (primary or zoster) and bacterial furunculosis; drug reactions (20%), such as morbilliform drug eruptions; vascular (8%), such as vasculitis and calciphylaxis; neoplastic (7%), such as keratinocyte carcinomas and leukemia cutis; and other (15%), such as xerosis, keratosis pilaris, and miliaria rubra.

Impact on Diagnosis—Fifty-six percent of all consultations resulted in a change in diagnosis. When dermatology was consulted specifically to assist in the diagnosis of a patient (195 consultations), the working diagnosis of the primary team was changed 69% of the time. Thirty-five of these consultation requests had no preliminary diagnosis, and the primary team listed the working diagnosis as either rash or a morphologic description of the lesion(s). Sixty-three percent of suspected drug eruptions ended with a diagnosis of a form of drug eruption, while 20% of consultations for suspected cellulitis or bacterial infections were confirmed to be cellulitis or soft tissue infections.

Impact on Management—Regardless of the reason for the consultation, most consultations (86%) resulted in a change in management. The remaining 14% consisted of FBSEs with benign findings; cases of cutaneous metastases and leukemia cutis managed by oncology; as well as select cases of purpura fulminans, postfebrile desquamation, and postinflammatory hyperpigmentation.

Changes in management included alterations in medications, requests for additional laboratory work or imaging, additional consultation requests, biopsies, or specific wound care instructions. Seventy-five percent of all consultations were given specific medication recommendations by dermatology. Most (61%) were recommended to be given a topical steroid, antibiotic, or both. However, 45% of all consultations were recommended to initiate a systemic medication, most commonly antihistamines, antibiotics, steroids, antivirals, or immunomodulators. Dermatology recommended discontinuing specific medications in 16% of all consultations, with antibiotics being the most frequent culprit (17 antibiotics discontinued), owing to drug eruptions or misdiagnosed infections. Vancomycin, piperacillin-tazobactam, and trimethoprim-sulfamethoxazole were the most frequently discontinued antibiotics.

Dermatology was consulted for assistance in management of previously diagnosed cutaneous conditions 56 times (22% of all consultations), often regarding complicated cases of hidradenitis suppurativa (9 cases), pyoderma gangrenosum (5 cases), bullous pemphigoid (4 cases), or erythroderma (4 cases). Most of these cases required a single dermatology encounter to provide recommendations (71%), and 21% required 1 additional follow-up. Sixty-three percent of patients consulted for management assistance were noted to have improvement in their cutaneous condition by time of discharge, as documented by the primary provider in the medical record.

Twenty-eight percent of all consultations required at least 1 biopsy. Seventy-two percent of all biopsies were consistent with the dermatologist’s working diagnosis or highest-ranked differential diagnosis, and 16% of biopsy results were consistent with the second- or third-ranked diagnosis. The primary teams requested a biopsy 38 times to assist in diagnosis, as documented in the progress note or consultation request. Only 21 of these consultations (55% of requests) received at least 1 biopsy, as the remaining consultations did not require a biopsy to establish a diagnosis. The most common final diagnoses of consultations receiving biopsies included drug eruptions (5), leukemia cutis (4), vasculopathies (4), vasculitis (4), and calciphylaxis (3).

Impact on Hospitalization and Efficacy—Dermatology performed 217 consultations regarding patients already admitted to the hospital, and 92% remained hospitalized either due to comorbidities or complicated cutaneous conditions following the consultation. The remaining 8% were cleared for discharge. Dermatology received 36 consultation requests from emergency medicine physicians. Fifty-three percent of these patients were admitted, while the remaining 47% were discharged from the emergency department or its observation unit following evaluation.

Fifty-one percent of all consultations were noted to have improvement in their cutaneous condition by the time of discharge, as noted in the physical examination, progress note, or discharge summary of the primary team. Thirty percent of cases remained stable, where improvement was not noted in in the medical record. Most of these cases involved keratinocyte carcinomas scheduled for outpatient excision, benign melanocytic nevi found on FBSE, and benign etiologies that led to immediate discharge following consultation. Three percent of all consultations were noted to have worsened following consultation, including cases of calciphylaxis, vasculopathies, and purpura fulminans, as well as patients who elected for palliative care and hospice. The cutaneous condition by the time of discharge could not be determined from the medical record in 16% of all consultations.

Eighty-five percent of all consultations required a single encounter with dermatology. An additional 10% required a single follow-up with dermatology, while only 5% of patients required 3 or more encounters. Notably, these cases included patients with 1 or more severe cutaneous diseases, such as Sweet syndrome, calciphylaxis, Stevens-Johnson syndrome/toxic epidermal necrolysis, and hidradenitis suppurativa.

Comment

Although dermatology often is viewed as an outpatient specialty, this study provides a glimpse into the ways inpatient dermatology consultations optimize the care of hospitalized patients. Most consultations involved assistance in diagnosing an unknown condition, but several regarded pre-existing skin disorders requiring management aid. As a variety of medical specialties requested consultations, dermatology was able to provide care to a diverse group of patients with conditions varying in complexity and severity. Several specialties benefited from niche dermatologic expertise: hematology and oncology frequently requested dermatology to assist in diagnosis and management of the toxic effects of chemotherapy, cutaneous metastasis, or suspected cutaneous infections in immunocompromised patients. Cardiology patients were frequently evaluated for potential malignancy or infection prior to heart transplantation and initiation of antirejection immunosuppressants. Dermatology was consulted to differentiate cutaneous manifestations of critical illness from underlying systemic disease in the intensive care unit, and patients presenting to the emergency department often were examined to determine if hospital admission was necessary, with 47% of these consultations resulting in a discharge following evaluation by a dermatologist.

Our results were consistent with prior studies^1,5,6 that have reported frequent changes in final diagnosis following dermatology consultation, with 69% of working diagnoses changed in this study when consultation was requested for diagnostic assistance. When dermatology was consulted for diagnostic assistance, several of these cases lacked a preliminary differential diagnosis. Although the absence of a documented differential diagnosis may not necessarily reflect a lack of suspicion for a particular etiology, 86% of all consultations included a ranked differential or working diagnosis either in the consultation request or progress note prior to consultation. The final diagnoses of consultations without a preliminary diagnosis varied from the mild and localized to systemic and severe, further suggesting these cases reflected knowledge gaps of the primary medical team.

Integration of dermatology into the care of hospitalized patients could provide an opportunity for education of primary medical teams. With frequent consultation, primary medical teams may become more comfortable diagnosing and managing common cutaneous conditions specific to their specialty or extended hospitalizations.

Several consultations were requested to aid in management of cases of hidradenitis suppurativa, pyoderma gangrenosum, or bullous pemphigoid that either failed outpatient therapy or were complicated by superinfections. Despite the ranges in complexity, the majority of all consultations required a single encounter and led to improvement by the time of discharge, demonstrating the efficacy and efficiency of inpatient dermatologists.

Dermatology consultations often led to changes in management involving medications and additional workup. Changes in management also extended to specific wound care instructions provided by dermatology, as expected for cases of Stevens-Johnson syndrome/toxic epidermal necrolysis, Sweet syndrome, hidradenitis suppurativa, and pyoderma gangrenosum. However, patients with the sequelae of extended hospitalizations, such as chronic wounds, pressure ulcers, and edema bullae, also benefited from this expertise.

When patients required a biopsy, the final diagnoses were consistent with the dermatologist’s number one differential diagnosis or top 3 differential diagnoses 72% and 88% of the time, respectively. Only 55% of cases where the primary team requested a biopsy ultimately required a biopsy, as many involved clinical diagnoses such as urticaria. Not only was dermatology accurate in their preliminary diagnoses, but they decreased cost and morbidity by avoiding unnecessary procedures.

This study provided additional evidence to support the integration of dermatology into the hospital setting for the benefit of patients, primary medical teams, and hospital systems. Dermatology offers high-value care through the efficient diagnosis and management of hospitalized patients, which contributes to decreased cost and improved outcomes.^2,5-7,9,10 This study highlighted lesser-known areas of impact, such as the various specialty-specific services dermatology provides as well as the high rates of reported improvement following consultation. Future studies should continue to explore the field’s unique impact on hospitalized medicine as well as other avenues of care delivery, such as telemedicine, that may encourage dermatologists to participate in consultations and increase the volume of patients who may benefit from their care.

Dermatology is an often-underutilized resource in the hospital setting. As the health care landscape has evolved, so has the role of the inpatient dermatologist.^1-3 Structural changes in the health system and advances in therapies have shifted dermatology from an admitting service to an almost exclusively outpatient practice. Improved treatment modalities led to decreases in the number of patients requiring admission for chronic dermatoses, and outpatient clinics began offering therapies once limited to hospitals.^1,4 Inpatient dermatology consultations emerged and continue to have profound effects on hospitalized patients regardless of their reason for admission.^1-11

Inpatient dermatologists supply knowledge in areas primary medical teams lack, and there is evidence that dermatology consultations improve the quality of care while decreasing cost.^2,5-7 Establishing correct diagnoses, preventing exposure to unnecessary medications, and reducing hospitalization duration and readmission rates are a few ways dermatology consultations positively impact hospitalized patients.^2,5-7,9,10 This study highlights the role of the dermatologist in the care of hospitalized patients at a large academic medical center in an urban setting and reveals how consultation supports the efficiency and efficacy of other services.

Materials and Methods

Study Design—This single-institution, cross-sectional retrospective study included all hospitalized patients at the Thomas Jefferson University Hospital (Philadelphia, Pennsylvania), who received an inpatient dermatology consultation completed by physicians of Jefferson Dermatology Associates between January 1, 2019, and December 31, 2019. The institutional review board at Thomas Jefferson University approved this study.

Data Collection—A list of all inpatient dermatology consultations in 2019 was provided by Jefferson Dermatology Associates. Through a retrospective chart review, data regarding the consultations were collected from the electronic medical record (Epic Systems) and recorded into the Research Electronic Data Capture system. Data on patient demographics, the primary medical team, the dermatology evaluation, and the hospital course of the patient were collected.

Results

Patient Characteristics—Dermatology received 253 inpatient consultation requests during this time period; 53% of patients were female and 47% were male, with a mean age of 55 years. Most patients were White (57%), while 34% were Black. Five percent and 4% of patients were Asian and Hispanic or Latino, respectively (Table 1). The mean duration of hospitalization for all patients was 15 days, and the average number of days to discharge following the first encounter with dermatology was 10 days.

Requesting Team and Reason for Consultation—Internal medicine consulted dermatology most frequently (34% of all consultations), followed by emergency medicine (14%) and a variety of other services (Table 1). Most dermatology consultations were placed to assist in achieving a diagnosis of a cutaneous condition (77%), while a minority were to assist in the management of a previously diagnosed disease (22%). A small fraction of consultations (5%) were to complete full-body skin examinations (FBSEs) to rule out infection or malignancy in candidates for organ transplantation, left ventricular assist devices, or certain chemotherapies. One FBSE was conducted to search for a primary tumor in a patient diagnosed with metastatic melanoma.

Most Common Final Diagnoses and Consultation Impact—Table 2 lists the most common final diagnosis categories, as well as the effects of the consultation on diagnosis, management, biopsies, hospitalization, and clinical improvement as documented by the primary medical provider. The most common final diagnoses were inflammatory and autoimmune (39%), such as contact dermatitis and seborrheic dermatitis; infectious (23%), such as varicella (primary or zoster) and bacterial furunculosis; drug reactions (20%), such as morbilliform drug eruptions; vascular (8%), such as vasculitis and calciphylaxis; neoplastic (7%), such as keratinocyte carcinomas and leukemia cutis; and other (15%), such as xerosis, keratosis pilaris, and miliaria rubra.

Impact on Diagnosis—Fifty-six percent of all consultations resulted in a change in diagnosis. When dermatology was consulted specifically to assist in the diagnosis of a patient (195 consultations), the working diagnosis of the primary team was changed 69% of the time. Thirty-five of these consultation requests had no preliminary diagnosis, and the primary team listed the working diagnosis as either rash or a morphologic description of the lesion(s). Sixty-three percent of suspected drug eruptions ended with a diagnosis of a form of drug eruption, while 20% of consultations for suspected cellulitis or bacterial infections were confirmed to be cellulitis or soft tissue infections.

Impact on Management—Regardless of the reason for the consultation, most consultations (86%) resulted in a change in management. The remaining 14% consisted of FBSEs with benign findings; cases of cutaneous metastases and leukemia cutis managed by oncology; as well as select cases of purpura fulminans, postfebrile desquamation, and postinflammatory hyperpigmentation.

Changes in management included alterations in medications, requests for additional laboratory work or imaging, additional consultation requests, biopsies, or specific wound care instructions. Seventy-five percent of all consultations were given specific medication recommendations by dermatology. Most (61%) were recommended to be given a topical steroid, antibiotic, or both. However, 45% of all consultations were recommended to initiate a systemic medication, most commonly antihistamines, antibiotics, steroids, antivirals, or immunomodulators. Dermatology recommended discontinuing specific medications in 16% of all consultations, with antibiotics being the most frequent culprit (17 antibiotics discontinued), owing to drug eruptions or misdiagnosed infections. Vancomycin, piperacillin-tazobactam, and trimethoprim-sulfamethoxazole were the most frequently discontinued antibiotics.

Dermatology was consulted for assistance in management of previously diagnosed cutaneous conditions 56 times (22% of all consultations), often regarding complicated cases of hidradenitis suppurativa (9 cases), pyoderma gangrenosum (5 cases), bullous pemphigoid (4 cases), or erythroderma (4 cases). Most of these cases required a single dermatology encounter to provide recommendations (71%), and 21% required 1 additional follow-up. Sixty-three percent of patients consulted for management assistance were noted to have improvement in their cutaneous condition by time of discharge, as documented by the primary provider in the medical record.

Twenty-eight percent of all consultations required at least 1 biopsy. Seventy-two percent of all biopsies were consistent with the dermatologist’s working diagnosis or highest-ranked differential diagnosis, and 16% of biopsy results were consistent with the second- or third-ranked diagnosis. The primary teams requested a biopsy 38 times to assist in diagnosis, as documented in the progress note or consultation request. Only 21 of these consultations (55% of requests) received at least 1 biopsy, as the remaining consultations did not require a biopsy to establish a diagnosis. The most common final diagnoses of consultations receiving biopsies included drug eruptions (5), leukemia cutis (4), vasculopathies (4), vasculitis (4), and calciphylaxis (3).

Impact on Hospitalization and Efficacy—Dermatology performed 217 consultations regarding patients already admitted to the hospital, and 92% remained hospitalized either due to comorbidities or complicated cutaneous conditions following the consultation. The remaining 8% were cleared for discharge. Dermatology received 36 consultation requests from emergency medicine physicians. Fifty-three percent of these patients were admitted, while the remaining 47% were discharged from the emergency department or its observation unit following evaluation.

Fifty-one percent of all consultations were noted to have improvement in their cutaneous condition by the time of discharge, as noted in the physical examination, progress note, or discharge summary of the primary team. Thirty percent of cases remained stable, where improvement was not noted in in the medical record. Most of these cases involved keratinocyte carcinomas scheduled for outpatient excision, benign melanocytic nevi found on FBSE, and benign etiologies that led to immediate discharge following consultation. Three percent of all consultations were noted to have worsened following consultation, including cases of calciphylaxis, vasculopathies, and purpura fulminans, as well as patients who elected for palliative care and hospice. The cutaneous condition by the time of discharge could not be determined from the medical record in 16% of all consultations.

Eighty-five percent of all consultations required a single encounter with dermatology. An additional 10% required a single follow-up with dermatology, while only 5% of patients required 3 or more encounters. Notably, these cases included patients with 1 or more severe cutaneous diseases, such as Sweet syndrome, calciphylaxis, Stevens-Johnson syndrome/toxic epidermal necrolysis, and hidradenitis suppurativa.

Comment

Although dermatology often is viewed as an outpatient specialty, this study provides a glimpse into the ways inpatient dermatology consultations optimize the care of hospitalized patients. Most consultations involved assistance in diagnosing an unknown condition, but several regarded pre-existing skin disorders requiring management aid. As a variety of medical specialties requested consultations, dermatology was able to provide care to a diverse group of patients with conditions varying in complexity and severity. Several specialties benefited from niche dermatologic expertise: hematology and oncology frequently requested dermatology to assist in diagnosis and management of the toxic effects of chemotherapy, cutaneous metastasis, or suspected cutaneous infections in immunocompromised patients. Cardiology patients were frequently evaluated for potential malignancy or infection prior to heart transplantation and initiation of antirejection immunosuppressants. Dermatology was consulted to differentiate cutaneous manifestations of critical illness from underlying systemic disease in the intensive care unit, and patients presenting to the emergency department often were examined to determine if hospital admission was necessary, with 47% of these consultations resulting in a discharge following evaluation by a dermatologist.

Our results were consistent with prior studies^1,5,6 that have reported frequent changes in final diagnosis following dermatology consultation, with 69% of working diagnoses changed in this study when consultation was requested for diagnostic assistance. When dermatology was consulted for diagnostic assistance, several of these cases lacked a preliminary differential diagnosis. Although the absence of a documented differential diagnosis may not necessarily reflect a lack of suspicion for a particular etiology, 86% of all consultations included a ranked differential or working diagnosis either in the consultation request or progress note prior to consultation. The final diagnoses of consultations without a preliminary diagnosis varied from the mild and localized to systemic and severe, further suggesting these cases reflected knowledge gaps of the primary medical team.

Integration of dermatology into the care of hospitalized patients could provide an opportunity for education of primary medical teams. With frequent consultation, primary medical teams may become more comfortable diagnosing and managing common cutaneous conditions specific to their specialty or extended hospitalizations.

Several consultations were requested to aid in management of cases of hidradenitis suppurativa, pyoderma gangrenosum, or bullous pemphigoid that either failed outpatient therapy or were complicated by superinfections. Despite the ranges in complexity, the majority of all consultations required a single encounter and led to improvement by the time of discharge, demonstrating the efficacy and efficiency of inpatient dermatologists.

Dermatology consultations often led to changes in management involving medications and additional workup. Changes in management also extended to specific wound care instructions provided by dermatology, as expected for cases of Stevens-Johnson syndrome/toxic epidermal necrolysis, Sweet syndrome, hidradenitis suppurativa, and pyoderma gangrenosum. However, patients with the sequelae of extended hospitalizations, such as chronic wounds, pressure ulcers, and edema bullae, also benefited from this expertise.

When patients required a biopsy, the final diagnoses were consistent with the dermatologist’s number one differential diagnosis or top 3 differential diagnoses 72% and 88% of the time, respectively. Only 55% of cases where the primary team requested a biopsy ultimately required a biopsy, as many involved clinical diagnoses such as urticaria. Not only was dermatology accurate in their preliminary diagnoses, but they decreased cost and morbidity by avoiding unnecessary procedures.

This study provided additional evidence to support the integration of dermatology into the hospital setting for the benefit of patients, primary medical teams, and hospital systems. Dermatology offers high-value care through the efficient diagnosis and management of hospitalized patients, which contributes to decreased cost and improved outcomes.^2,5-7,9,10 This study highlighted lesser-known areas of impact, such as the various specialty-specific services dermatology provides as well as the high rates of reported improvement following consultation. Future studies should continue to explore the field’s unique impact on hospitalized medicine as well as other avenues of care delivery, such as telemedicine, that may encourage dermatologists to participate in consultations and increase the volume of patients who may benefit from their care.

Dermatology is an often-underutilized resource in the hospital setting. As the health care landscape has evolved, so has the role of the inpatient dermatologist.^1-3 Structural changes in the health system and advances in therapies have shifted dermatology from an admitting service to an almost exclusively outpatient practice. Improved treatment modalities led to decreases in the number of patients requiring admission for chronic dermatoses, and outpatient clinics began offering therapies once limited to hospitals.^1,4 Inpatient dermatology consultations emerged and continue to have profound effects on hospitalized patients regardless of their reason for admission.^1-11

Inpatient dermatologists supply knowledge in areas primary medical teams lack, and there is evidence that dermatology consultations improve the quality of care while decreasing cost.^2,5-7 Establishing correct diagnoses, preventing exposure to unnecessary medications, and reducing hospitalization duration and readmission rates are a few ways dermatology consultations positively impact hospitalized patients.^2,5-7,9,10 This study highlights the role of the dermatologist in the care of hospitalized patients at a large academic medical center in an urban setting and reveals how consultation supports the efficiency and efficacy of other services.

Materials and Methods

Study Design—This single-institution, cross-sectional retrospective study included all hospitalized patients at the Thomas Jefferson University Hospital (Philadelphia, Pennsylvania), who received an inpatient dermatology consultation completed by physicians of Jefferson Dermatology Associates between January 1, 2019, and December 31, 2019. The institutional review board at Thomas Jefferson University approved this study.

Data Collection—A list of all inpatient dermatology consultations in 2019 was provided by Jefferson Dermatology Associates. Through a retrospective chart review, data regarding the consultations were collected from the electronic medical record (Epic Systems) and recorded into the Research Electronic Data Capture system. Data on patient demographics, the primary medical team, the dermatology evaluation, and the hospital course of the patient were collected.

Results

Patient Characteristics—Dermatology received 253 inpatient consultation requests during this time period; 53% of patients were female and 47% were male, with a mean age of 55 years. Most patients were White (57%), while 34% were Black. Five percent and 4% of patients were Asian and Hispanic or Latino, respectively (Table 1). The mean duration of hospitalization for all patients was 15 days, and the average number of days to discharge following the first encounter with dermatology was 10 days.

Requesting Team and Reason for Consultation—Internal medicine consulted dermatology most frequently (34% of all consultations), followed by emergency medicine (14%) and a variety of other services (Table 1). Most dermatology consultations were placed to assist in achieving a diagnosis of a cutaneous condition (77%), while a minority were to assist in the management of a previously diagnosed disease (22%). A small fraction of consultations (5%) were to complete full-body skin examinations (FBSEs) to rule out infection or malignancy in candidates for organ transplantation, left ventricular assist devices, or certain chemotherapies. One FBSE was conducted to search for a primary tumor in a patient diagnosed with metastatic melanoma.

Most Common Final Diagnoses and Consultation Impact—Table 2 lists the most common final diagnosis categories, as well as the effects of the consultation on diagnosis, management, biopsies, hospitalization, and clinical improvement as documented by the primary medical provider. The most common final diagnoses were inflammatory and autoimmune (39%), such as contact dermatitis and seborrheic dermatitis; infectious (23%), such as varicella (primary or zoster) and bacterial furunculosis; drug reactions (20%), such as morbilliform drug eruptions; vascular (8%), such as vasculitis and calciphylaxis; neoplastic (7%), such as keratinocyte carcinomas and leukemia cutis; and other (15%), such as xerosis, keratosis pilaris, and miliaria rubra.

Impact on Diagnosis—Fifty-six percent of all consultations resulted in a change in diagnosis. When dermatology was consulted specifically to assist in the diagnosis of a patient (195 consultations), the working diagnosis of the primary team was changed 69% of the time. Thirty-five of these consultation requests had no preliminary diagnosis, and the primary team listed the working diagnosis as either rash or a morphologic description of the lesion(s). Sixty-three percent of suspected drug eruptions ended with a diagnosis of a form of drug eruption, while 20% of consultations for suspected cellulitis or bacterial infections were confirmed to be cellulitis or soft tissue infections.

Impact on Management—Regardless of the reason for the consultation, most consultations (86%) resulted in a change in management. The remaining 14% consisted of FBSEs with benign findings; cases of cutaneous metastases and leukemia cutis managed by oncology; as well as select cases of purpura fulminans, postfebrile desquamation, and postinflammatory hyperpigmentation.

Changes in management included alterations in medications, requests for additional laboratory work or imaging, additional consultation requests, biopsies, or specific wound care instructions. Seventy-five percent of all consultations were given specific medication recommendations by dermatology. Most (61%) were recommended to be given a topical steroid, antibiotic, or both. However, 45% of all consultations were recommended to initiate a systemic medication, most commonly antihistamines, antibiotics, steroids, antivirals, or immunomodulators. Dermatology recommended discontinuing specific medications in 16% of all consultations, with antibiotics being the most frequent culprit (17 antibiotics discontinued), owing to drug eruptions or misdiagnosed infections. Vancomycin, piperacillin-tazobactam, and trimethoprim-sulfamethoxazole were the most frequently discontinued antibiotics.

Dermatology was consulted for assistance in management of previously diagnosed cutaneous conditions 56 times (22% of all consultations), often regarding complicated cases of hidradenitis suppurativa (9 cases), pyoderma gangrenosum (5 cases), bullous pemphigoid (4 cases), or erythroderma (4 cases). Most of these cases required a single dermatology encounter to provide recommendations (71%), and 21% required 1 additional follow-up. Sixty-three percent of patients consulted for management assistance were noted to have improvement in their cutaneous condition by time of discharge, as documented by the primary provider in the medical record.

Twenty-eight percent of all consultations required at least 1 biopsy. Seventy-two percent of all biopsies were consistent with the dermatologist’s working diagnosis or highest-ranked differential diagnosis, and 16% of biopsy results were consistent with the second- or third-ranked diagnosis. The primary teams requested a biopsy 38 times to assist in diagnosis, as documented in the progress note or consultation request. Only 21 of these consultations (55% of requests) received at least 1 biopsy, as the remaining consultations did not require a biopsy to establish a diagnosis. The most common final diagnoses of consultations receiving biopsies included drug eruptions (5), leukemia cutis (4), vasculopathies (4), vasculitis (4), and calciphylaxis (3).

Impact on Hospitalization and Efficacy—Dermatology performed 217 consultations regarding patients already admitted to the hospital, and 92% remained hospitalized either due to comorbidities or complicated cutaneous conditions following the consultation. The remaining 8% were cleared for discharge. Dermatology received 36 consultation requests from emergency medicine physicians. Fifty-three percent of these patients were admitted, while the remaining 47% were discharged from the emergency department or its observation unit following evaluation.

Fifty-one percent of all consultations were noted to have improvement in their cutaneous condition by the time of discharge, as noted in the physical examination, progress note, or discharge summary of the primary team. Thirty percent of cases remained stable, where improvement was not noted in in the medical record. Most of these cases involved keratinocyte carcinomas scheduled for outpatient excision, benign melanocytic nevi found on FBSE, and benign etiologies that led to immediate discharge following consultation. Three percent of all consultations were noted to have worsened following consultation, including cases of calciphylaxis, vasculopathies, and purpura fulminans, as well as patients who elected for palliative care and hospice. The cutaneous condition by the time of discharge could not be determined from the medical record in 16% of all consultations.

Eighty-five percent of all consultations required a single encounter with dermatology. An additional 10% required a single follow-up with dermatology, while only 5% of patients required 3 or more encounters. Notably, these cases included patients with 1 or more severe cutaneous diseases, such as Sweet syndrome, calciphylaxis, Stevens-Johnson syndrome/toxic epidermal necrolysis, and hidradenitis suppurativa.

Comment

Although dermatology often is viewed as an outpatient specialty, this study provides a glimpse into the ways inpatient dermatology consultations optimize the care of hospitalized patients. Most consultations involved assistance in diagnosing an unknown condition, but several regarded pre-existing skin disorders requiring management aid. As a variety of medical specialties requested consultations, dermatology was able to provide care to a diverse group of patients with conditions varying in complexity and severity. Several specialties benefited from niche dermatologic expertise: hematology and oncology frequently requested dermatology to assist in diagnosis and management of the toxic effects of chemotherapy, cutaneous metastasis, or suspected cutaneous infections in immunocompromised patients. Cardiology patients were frequently evaluated for potential malignancy or infection prior to heart transplantation and initiation of antirejection immunosuppressants. Dermatology was consulted to differentiate cutaneous manifestations of critical illness from underlying systemic disease in the intensive care unit, and patients presenting to the emergency department often were examined to determine if hospital admission was necessary, with 47% of these consultations resulting in a discharge following evaluation by a dermatologist.

Our results were consistent with prior studies^1,5,6 that have reported frequent changes in final diagnosis following dermatology consultation, with 69% of working diagnoses changed in this study when consultation was requested for diagnostic assistance. When dermatology was consulted for diagnostic assistance, several of these cases lacked a preliminary differential diagnosis. Although the absence of a documented differential diagnosis may not necessarily reflect a lack of suspicion for a particular etiology, 86% of all consultations included a ranked differential or working diagnosis either in the consultation request or progress note prior to consultation. The final diagnoses of consultations without a preliminary diagnosis varied from the mild and localized to systemic and severe, further suggesting these cases reflected knowledge gaps of the primary medical team.

Integration of dermatology into the care of hospitalized patients could provide an opportunity for education of primary medical teams. With frequent consultation, primary medical teams may become more comfortable diagnosing and managing common cutaneous conditions specific to their specialty or extended hospitalizations.

Several consultations were requested to aid in management of cases of hidradenitis suppurativa, pyoderma gangrenosum, or bullous pemphigoid that either failed outpatient therapy or were complicated by superinfections. Despite the ranges in complexity, the majority of all consultations required a single encounter and led to improvement by the time of discharge, demonstrating the efficacy and efficiency of inpatient dermatologists.

Dermatology consultations often led to changes in management involving medications and additional workup. Changes in management also extended to specific wound care instructions provided by dermatology, as expected for cases of Stevens-Johnson syndrome/toxic epidermal necrolysis, Sweet syndrome, hidradenitis suppurativa, and pyoderma gangrenosum. However, patients with the sequelae of extended hospitalizations, such as chronic wounds, pressure ulcers, and edema bullae, also benefited from this expertise.

When patients required a biopsy, the final diagnoses were consistent with the dermatologist’s number one differential diagnosis or top 3 differential diagnoses 72% and 88% of the time, respectively. Only 55% of cases where the primary team requested a biopsy ultimately required a biopsy, as many involved clinical diagnoses such as urticaria. Not only was dermatology accurate in their preliminary diagnoses, but they decreased cost and morbidity by avoiding unnecessary procedures.

This study provided additional evidence to support the integration of dermatology into the hospital setting for the benefit of patients, primary medical teams, and hospital systems. Dermatology offers high-value care through the efficient diagnosis and management of hospitalized patients, which contributes to decreased cost and improved outcomes.^2,5-7,9,10 This study highlighted lesser-known areas of impact, such as the various specialty-specific services dermatology provides as well as the high rates of reported improvement following consultation. Future studies should continue to explore the field’s unique impact on hospitalized medicine as well as other avenues of care delivery, such as telemedicine, that may encourage dermatologists to participate in consultations and increase the volume of patients who may benefit from their care.

To the Editor:

A 59-year-old man presented with a severely pruritic rash on the legs, arms, abdomen, groin, and buttocks of 3 days’ duration. He reported subjective fever and chills. Prior to the appearance of the rash, the patient and his family had eaten shiitake mushrooms daily for 3 days. He denied any new medications in the last several months or any recent upper respiratory or gastrointestinal tract illnesses. His medical history included type 2 diabetes mellitus and diabetes-induced end-stage renal disease requiring home peritoneal dialysis. His long-term medications for diabetes mellitus, hypertension, benign prostatic hyperplasia, hyperlipidemia, and insomnia included amlodipine, atorvastatin, finasteride, gabapentin, insulin glargine, linagliptin, metoprolol, and mirtazapine.

Physical examination revealed an afebrile man with medium brown skin tone and diffuse, bright red, erythematous patches on the lower legs, axillae, medial forearms, lateral trunk, lower abdomen, and groin. There were distinct flagellate, linear, red patches on the lower legs (Figure 1). In addition, small clusters of 1- to 2-mm superficial pustules were present on the right upper medial thigh and left forearm with micropapules grouped in the skin folds.

A shave biopsy specimen from a pustule on the right upper medial thigh revealed spongiotic dermatitis with neutrophilic subcorneal pustule formation and frequent eosinophils (Figure 2). The dermis contained scattered mixed inflammatory cells including neutrophils, eosinophils, lymphocytes, and histiocytes (Figure 3). These histologic findings were consistent with acute generalized exanthematous pustulosis (AGEP). No biopsy was performed on the flagellate patches due to its clinically distinct presentation and well-established association with shiitake mushroom ingestion.

The patient was treated with triamcinolone ointment and systemic corticosteroids to reduce pruritus and quickly clear the lesions due to his comorbidities. He recovered completely within 1 week and had no evidence of postinflammatory hyperpigmentation from the flagellate dermatitis.

Flagellate dermatitis is an intensely pruritic dermatitis characterized by 1-mm, disseminated, erythematous papules in a linear grouped arrangement secondary to koebnerization due to the patient scratching. It was first described in 1977 by Nakamura.¹ Although it rarely is seen outside of China and Japan, there are well-established associations of flagellate dermatitis with bleomycin and shiitake mushroom (Lentinula edodes) ingestion. One key clinical difference between the two causes is that postinflammatory hyperpigmentation changes usually are seen with bleomycin-induced flagellate dermatitis and typically are not present with shiitake mushroom–induced flagellate dermatitis.² Following ingestion of shiitake mushrooms, the median time of onset of presentation typically is 24 hours but ranges from 12 hours to 5 days. Most patients completely recover by 3 weeks, with or without treatment.³ Although the pathogenesis of shiitake mushroom–induced flagellate dermatitis is not clear, the most common theory is a toxic reaction to lentinan, a polysaccharide isolated from shiitake mushrooms. However, type I and IV allergic hypersensitivities also have been supported by the time of onset, clearance, severe pruritus, benefit from steroids and antihistamines, and lack of grouped outbreaks in people exposed to shared meals containing shiitake mushrooms.^3,4 Furthermore, there is a case of patch test–confirmed allergic contact dermatitis to shiitake mushrooms, demonstrating a 1+ reaction at 96 hours to the cap of a shiitake mushroom but a negative pin-prick test at 20 minutes, suggesting type IV hypersensitivity.⁵ An additional case revealed a positive skin-prick test with formation of a 4-mm wheal and subsequent pruritic papules and vesicles appearing 48 to 72 hours later at the prick site.⁶ Subsequent cases have been reported in association with consumption of raw shiitake mushrooms, but cases have been reported after consumption of fully cooked mushrooms, which does not support a toxin-mediated theory, as cooking the mushroom before consumption likely would denature or change the structure of the suspected toxin.²

Acute generalized exanthematous pustulosis is a rare eruption that occurs due to ingestion of a causative agent, usually an antibiotic, and is characterized by the presence of fever and disseminated, erythematous, pinpoint, sterile pustules on the skin and mucous membranes. It affects 1 to 5 persons per million per year, with more than 90% of cases attributed to drug ingestion.⁷ Spontaneous resolution can be expected within 15 days of its onset; however, there is a mortality rate of up to 5% that occurs most often in those with severe comorbidities or in older patients, for whom systemic corticosteroid therapy may be justified.^7,8 A multinational case-control study conducted to evaluate the risk of AGEP associated with certain drugs revealed macrolides (namely pristinamycin); β-lactam antibiotics including penicillin, aminopenicillin, and cephalosporin; quinolones; hydroxychloroquine; anti-infective sulfonamides; terbinafine; and diltiazem as the most strongly associated culprits.⁹ Our patient’s flagellate dermatitis was unique in that it also showed histologic features of AGEP. The pathogenesis of drug-induced AGEP has been partially elucidated and involves activation of drug-specific CD4⁺ and CD8⁺ T cells that migrate to the skin and participate in apoptotic signaling of keratinocytes and recruitment of neutrophils and eosinophils, which form subcorneal sterile pustules.⁷ In a study of severe cutaneous adverse drug reactions, 50% (7/14) of patients with AGEP had positive patch tests to the causative agent.¹⁰ This T cell–dependent response explains why the condition responds to systemic corticosteroids. Additionally, our case report of shiitake mushroom–induced flagellate dermatitis with histologic features of AGEP suggests that the pathogenesis of flagellate dermatitis may be a T cell–mediated type IV hypersensitivity reaction. The time of onset, lack of grouped outbreaks in those sharing shiitake mushroom–containing meals, severe pruritus, lack of cases demonstrating an anaphylactic or wheal and flare response, benefit of steroids, and a case with histologic features of AGEP all lend support to this theory.

We report a case of shiitake mushroom–induced flagellate dermatitis with histologic features of AGEP. The time course, histologic features of AGEP, absence of new medications, and resolution with discontinuation of shiitake mushrooms lends support of the hypothesis that the pathogenesis of shiitake mushroom–induced flagellate dermatitis is similar to AGEP’s type IV hypersensitivity reaction. To further elucidate its pathogenesis, skin prick testing and patch testing with shiitake mushrooms in patients exhibiting shiitake mushroom–induced flagellate dermatitis may prove to be beneficial.

To the Editor:

A 59-year-old man presented with a severely pruritic rash on the legs, arms, abdomen, groin, and buttocks of 3 days’ duration. He reported subjective fever and chills. Prior to the appearance of the rash, the patient and his family had eaten shiitake mushrooms daily for 3 days. He denied any new medications in the last several months or any recent upper respiratory or gastrointestinal tract illnesses. His medical history included type 2 diabetes mellitus and diabetes-induced end-stage renal disease requiring home peritoneal dialysis. His long-term medications for diabetes mellitus, hypertension, benign prostatic hyperplasia, hyperlipidemia, and insomnia included amlodipine, atorvastatin, finasteride, gabapentin, insulin glargine, linagliptin, metoprolol, and mirtazapine.

Physical examination revealed an afebrile man with medium brown skin tone and diffuse, bright red, erythematous patches on the lower legs, axillae, medial forearms, lateral trunk, lower abdomen, and groin. There were distinct flagellate, linear, red patches on the lower legs (Figure 1). In addition, small clusters of 1- to 2-mm superficial pustules were present on the right upper medial thigh and left forearm with micropapules grouped in the skin folds.

A shave biopsy specimen from a pustule on the right upper medial thigh revealed spongiotic dermatitis with neutrophilic subcorneal pustule formation and frequent eosinophils (Figure 2). The dermis contained scattered mixed inflammatory cells including neutrophils, eosinophils, lymphocytes, and histiocytes (Figure 3). These histologic findings were consistent with acute generalized exanthematous pustulosis (AGEP). No biopsy was performed on the flagellate patches due to its clinically distinct presentation and well-established association with shiitake mushroom ingestion.

The patient was treated with triamcinolone ointment and systemic corticosteroids to reduce pruritus and quickly clear the lesions due to his comorbidities. He recovered completely within 1 week and had no evidence of postinflammatory hyperpigmentation from the flagellate dermatitis.

Flagellate dermatitis is an intensely pruritic dermatitis characterized by 1-mm, disseminated, erythematous papules in a linear grouped arrangement secondary to koebnerization due to the patient scratching. It was first described in 1977 by Nakamura.¹ Although it rarely is seen outside of China and Japan, there are well-established associations of flagellate dermatitis with bleomycin and shiitake mushroom (Lentinula edodes) ingestion. One key clinical difference between the two causes is that postinflammatory hyperpigmentation changes usually are seen with bleomycin-induced flagellate dermatitis and typically are not present with shiitake mushroom–induced flagellate dermatitis.² Following ingestion of shiitake mushrooms, the median time of onset of presentation typically is 24 hours but ranges from 12 hours to 5 days. Most patients completely recover by 3 weeks, with or without treatment.³ Although the pathogenesis of shiitake mushroom–induced flagellate dermatitis is not clear, the most common theory is a toxic reaction to lentinan, a polysaccharide isolated from shiitake mushrooms. However, type I and IV allergic hypersensitivities also have been supported by the time of onset, clearance, severe pruritus, benefit from steroids and antihistamines, and lack of grouped outbreaks in people exposed to shared meals containing shiitake mushrooms.^3,4 Furthermore, there is a case of patch test–confirmed allergic contact dermatitis to shiitake mushrooms, demonstrating a 1+ reaction at 96 hours to the cap of a shiitake mushroom but a negative pin-prick test at 20 minutes, suggesting type IV hypersensitivity.⁵ An additional case revealed a positive skin-prick test with formation of a 4-mm wheal and subsequent pruritic papules and vesicles appearing 48 to 72 hours later at the prick site.⁶ Subsequent cases have been reported in association with consumption of raw shiitake mushrooms, but cases have been reported after consumption of fully cooked mushrooms, which does not support a toxin-mediated theory, as cooking the mushroom before consumption likely would denature or change the structure of the suspected toxin.²

Acute generalized exanthematous pustulosis is a rare eruption that occurs due to ingestion of a causative agent, usually an antibiotic, and is characterized by the presence of fever and disseminated, erythematous, pinpoint, sterile pustules on the skin and mucous membranes. It affects 1 to 5 persons per million per year, with more than 90% of cases attributed to drug ingestion.⁷ Spontaneous resolution can be expected within 15 days of its onset; however, there is a mortality rate of up to 5% that occurs most often in those with severe comorbidities or in older patients, for whom systemic corticosteroid therapy may be justified.^7,8 A multinational case-control study conducted to evaluate the risk of AGEP associated with certain drugs revealed macrolides (namely pristinamycin); β-lactam antibiotics including penicillin, aminopenicillin, and cephalosporin; quinolones; hydroxychloroquine; anti-infective sulfonamides; terbinafine; and diltiazem as the most strongly associated culprits.⁹ Our patient’s flagellate dermatitis was unique in that it also showed histologic features of AGEP. The pathogenesis of drug-induced AGEP has been partially elucidated and involves activation of drug-specific CD4⁺ and CD8⁺ T cells that migrate to the skin and participate in apoptotic signaling of keratinocytes and recruitment of neutrophils and eosinophils, which form subcorneal sterile pustules.⁷ In a study of severe cutaneous adverse drug reactions, 50% (7/14) of patients with AGEP had positive patch tests to the causative agent.¹⁰ This T cell–dependent response explains why the condition responds to systemic corticosteroids. Additionally, our case report of shiitake mushroom–induced flagellate dermatitis with histologic features of AGEP suggests that the pathogenesis of flagellate dermatitis may be a T cell–mediated type IV hypersensitivity reaction. The time of onset, lack of grouped outbreaks in those sharing shiitake mushroom–containing meals, severe pruritus, lack of cases demonstrating an anaphylactic or wheal and flare response, benefit of steroids, and a case with histologic features of AGEP all lend support to this theory.

We report a case of shiitake mushroom–induced flagellate dermatitis with histologic features of AGEP. The time course, histologic features of AGEP, absence of new medications, and resolution with discontinuation of shiitake mushrooms lends support of the hypothesis that the pathogenesis of shiitake mushroom–induced flagellate dermatitis is similar to AGEP’s type IV hypersensitivity reaction. To further elucidate its pathogenesis, skin prick testing and patch testing with shiitake mushrooms in patients exhibiting shiitake mushroom–induced flagellate dermatitis may prove to be beneficial.

To the Editor:

A 59-year-old man presented with a severely pruritic rash on the legs, arms, abdomen, groin, and buttocks of 3 days’ duration. He reported subjective fever and chills. Prior to the appearance of the rash, the patient and his family had eaten shiitake mushrooms daily for 3 days. He denied any new medications in the last several months or any recent upper respiratory or gastrointestinal tract illnesses. His medical history included type 2 diabetes mellitus and diabetes-induced end-stage renal disease requiring home peritoneal dialysis. His long-term medications for diabetes mellitus, hypertension, benign prostatic hyperplasia, hyperlipidemia, and insomnia included amlodipine, atorvastatin, finasteride, gabapentin, insulin glargine, linagliptin, metoprolol, and mirtazapine.

Physical examination revealed an afebrile man with medium brown skin tone and diffuse, bright red, erythematous patches on the lower legs, axillae, medial forearms, lateral trunk, lower abdomen, and groin. There were distinct flagellate, linear, red patches on the lower legs (Figure 1). In addition, small clusters of 1- to 2-mm superficial pustules were present on the right upper medial thigh and left forearm with micropapules grouped in the skin folds.

A shave biopsy specimen from a pustule on the right upper medial thigh revealed spongiotic dermatitis with neutrophilic subcorneal pustule formation and frequent eosinophils (Figure 2). The dermis contained scattered mixed inflammatory cells including neutrophils, eosinophils, lymphocytes, and histiocytes (Figure 3). These histologic findings were consistent with acute generalized exanthematous pustulosis (AGEP). No biopsy was performed on the flagellate patches due to its clinically distinct presentation and well-established association with shiitake mushroom ingestion.

The patient was treated with triamcinolone ointment and systemic corticosteroids to reduce pruritus and quickly clear the lesions due to his comorbidities. He recovered completely within 1 week and had no evidence of postinflammatory hyperpigmentation from the flagellate dermatitis.

Flagellate dermatitis is an intensely pruritic dermatitis characterized by 1-mm, disseminated, erythematous papules in a linear grouped arrangement secondary to koebnerization due to the patient scratching. It was first described in 1977 by Nakamura.¹ Although it rarely is seen outside of China and Japan, there are well-established associations of flagellate dermatitis with bleomycin and shiitake mushroom (Lentinula edodes) ingestion. One key clinical difference between the two causes is that postinflammatory hyperpigmentation changes usually are seen with bleomycin-induced flagellate dermatitis and typically are not present with shiitake mushroom–induced flagellate dermatitis.² Following ingestion of shiitake mushrooms, the median time of onset of presentation typically is 24 hours but ranges from 12 hours to 5 days. Most patients completely recover by 3 weeks, with or without treatment.³ Although the pathogenesis of shiitake mushroom–induced flagellate dermatitis is not clear, the most common theory is a toxic reaction to lentinan, a polysaccharide isolated from shiitake mushrooms. However, type I and IV allergic hypersensitivities also have been supported by the time of onset, clearance, severe pruritus, benefit from steroids and antihistamines, and lack of grouped outbreaks in people exposed to shared meals containing shiitake mushrooms.^3,4 Furthermore, there is a case of patch test–confirmed allergic contact dermatitis to shiitake mushrooms, demonstrating a 1+ reaction at 96 hours to the cap of a shiitake mushroom but a negative pin-prick test at 20 minutes, suggesting type IV hypersensitivity.⁵ An additional case revealed a positive skin-prick test with formation of a 4-mm wheal and subsequent pruritic papules and vesicles appearing 48 to 72 hours later at the prick site.⁶ Subsequent cases have been reported in association with consumption of raw shiitake mushrooms, but cases have been reported after consumption of fully cooked mushrooms, which does not support a toxin-mediated theory, as cooking the mushroom before consumption likely would denature or change the structure of the suspected toxin.²

Acute generalized exanthematous pustulosis is a rare eruption that occurs due to ingestion of a causative agent, usually an antibiotic, and is characterized by the presence of fever and disseminated, erythematous, pinpoint, sterile pustules on the skin and mucous membranes. It affects 1 to 5 persons per million per year, with more than 90% of cases attributed to drug ingestion.⁷ Spontaneous resolution can be expected within 15 days of its onset; however, there is a mortality rate of up to 5% that occurs most often in those with severe comorbidities or in older patients, for whom systemic corticosteroid therapy may be justified.^7,8 A multinational case-control study conducted to evaluate the risk of AGEP associated with certain drugs revealed macrolides (namely pristinamycin); β-lactam antibiotics including penicillin, aminopenicillin, and cephalosporin; quinolones; hydroxychloroquine; anti-infective sulfonamides; terbinafine; and diltiazem as the most strongly associated culprits.⁹ Our patient’s flagellate dermatitis was unique in that it also showed histologic features of AGEP. The pathogenesis of drug-induced AGEP has been partially elucidated and involves activation of drug-specific CD4⁺ and CD8⁺ T cells that migrate to the skin and participate in apoptotic signaling of keratinocytes and recruitment of neutrophils and eosinophils, which form subcorneal sterile pustules.⁷ In a study of severe cutaneous adverse drug reactions, 50% (7/14) of patients with AGEP had positive patch tests to the causative agent.¹⁰ This T cell–dependent response explains why the condition responds to systemic corticosteroids. Additionally, our case report of shiitake mushroom–induced flagellate dermatitis with histologic features of AGEP suggests that the pathogenesis of flagellate dermatitis may be a T cell–mediated type IV hypersensitivity reaction. The time of onset, lack of grouped outbreaks in those sharing shiitake mushroom–containing meals, severe pruritus, lack of cases demonstrating an anaphylactic or wheal and flare response, benefit of steroids, and a case with histologic features of AGEP all lend support to this theory.

We report a case of shiitake mushroom–induced flagellate dermatitis with histologic features of AGEP. The time course, histologic features of AGEP, absence of new medications, and resolution with discontinuation of shiitake mushrooms lends support of the hypothesis that the pathogenesis of shiitake mushroom–induced flagellate dermatitis is similar to AGEP’s type IV hypersensitivity reaction. To further elucidate its pathogenesis, skin prick testing and patch testing with shiitake mushrooms in patients exhibiting shiitake mushroom–induced flagellate dermatitis may prove to be beneficial.

The Diagnosis: Dermatitis Neglecta

A punch biopsy of the abdomen revealed hyperkeratosis and mild papillomatosis (Figure), which can be seen in dermatitis neglecta (DN) and acanthosis nigricans (AN) as well as confluent and reticulated papillomatosis (CARP). Due to the patient’s history of mood and psychotic disorders, collateral information was obtained from the patient’s family, who reported that the patient had a depressed mood in the last few months and was not showering or caring for herself during this period. There was no additional personal or family history of skin disease. Clinical and histopathologic findings led to a diagnosis of DN. Following recommendations for daily cleansing with soap and water along with topical ammonium lactate, near-complete resolution of the rash was achieved in 3 weeks.

Dermatitis neglecta, or unwashed dermatosis, is a skin condition that occurs secondary to poor hygiene, which was first reported in 1995 by Poskitt et al.¹ Avoidance of washing in affected areas can be due to physical disability, pain after injury, neurological deficit, or psychologically induced fear or neglect. Sebum, sweat, corneocytes, and bacteria combine into compact adherent crusts of dirt, which appear as hyperkeratotic plaques with cornflakelike scale.^2,3 Despite its innate simplicity, DN is a diagnostic challenge, as it clinically and histologically mimics other dermatoses including AN, terra firmaforme dermatosis, and CARP.^2,4 Ultimately, the diagnosis of DN can be made when a history of poor hygiene is probable or elicited, and lesions can be removed with soap and water. Treatment of DN includes daily cleansing with soap and water; however, resistant lesions or extensive disease may require keratolytic agents, as in our patient.^2-4 In contrast, terra firma-forme dermatosis, which may look similar, is not due to poor hygiene, and the lesions typically are resistant to soap and water, classically requiring isopropyl alcohol for removal. Overall, maintained awareness of DN is imperative, as early diagnosis can avoid unnecessary biopsies and more complex treatment measures as well as facilitate coordination of care when additional medical or psychiatric concerns are present.

Although the diagnoses of DN and terra firma-forme dermatosis can be distinguished based on the patient’s clinical history and response to simple cleansing measures alone, the alternate diagnoses can be excluded based on different clinical distributions and response to other treatment modalities but sometimes may require clinicopathologic correlation for definitive diagnosis. Our patient had a biopsy diagnosis of psoriasiform dermatitis from an outside provider, but neither her clinical disease nor repeated histopathologic findings supported a diagnosis of psoriasis or other classic psoriasiform dermatoses such as contact dermatitis, dermatophyte/ candidal infection, seborrheic dermatitis, pityriasis rubra pilaris, pityriasis rosea, scabies, or syphilis.

It is imperative to exclude alternative diagnoses because they can have systemic implications and can misguide treatment, as was done initially with our patient. Psoriasis vulgaris in its classic form is a chronic inflammatory skin disease that manifests as sharply demarcated, erythematous plaques with overlying thick silvery scale; it has the additional histologic findings of neutrophilic spongiform pustules in the epidermis, tortuous blood vessels in the papillary dermis, and neutrophils and parakeratosis in the stratum corneum. In its benign form, AN is associated with endocrinopathies, most commonly obesity and insulin-resistant diabetes mellitus, and presents as hyperkeratotic, velvety, hyperpigmented plaques typically limited to the neck and axillae. Malignant AN spontaneously arises in association with systemic malignancy and can be extensive and generalized.⁵ Treatment of AN primarily focuses on resolution of the underlying systemic disease; however, cosmetic treatment with topical or oral retinoids may hasten resolution of cutaneous disease.⁶ Confluent and reticulated papillomatosis is characterized by reticulated hyperkeratotic plaques with a common distribution over the central and upper trunk. Unlike DN and AN, which may occur at any age, CARP typically is seen in adolescents and young adults.⁷ There is no evidence-based gold standard for the management of CARP; however, the successful use of various antibiotics, antifungals, and retinoids—alone or in combination—has been reported.⁸ Overall, compared to the other entities in the differential diagnosis, DN easily can be prevented with consistent use of soap and water and may be underreported given the asymptomatic nature of the disease and the typical patient population.

The Diagnosis: Dermatitis Neglecta

A punch biopsy of the abdomen revealed hyperkeratosis and mild papillomatosis (Figure), which can be seen in dermatitis neglecta (DN) and acanthosis nigricans (AN) as well as confluent and reticulated papillomatosis (CARP). Due to the patient’s history of mood and psychotic disorders, collateral information was obtained from the patient’s family, who reported that the patient had a depressed mood in the last few months and was not showering or caring for herself during this period. There was no additional personal or family history of skin disease. Clinical and histopathologic findings led to a diagnosis of DN. Following recommendations for daily cleansing with soap and water along with topical ammonium lactate, near-complete resolution of the rash was achieved in 3 weeks.

Dermatitis neglecta, or unwashed dermatosis, is a skin condition that occurs secondary to poor hygiene, which was first reported in 1995 by Poskitt et al.¹ Avoidance of washing in affected areas can be due to physical disability, pain after injury, neurological deficit, or psychologically induced fear or neglect. Sebum, sweat, corneocytes, and bacteria combine into compact adherent crusts of dirt, which appear as hyperkeratotic plaques with cornflakelike scale.^2,3 Despite its innate simplicity, DN is a diagnostic challenge, as it clinically and histologically mimics other dermatoses including AN, terra firmaforme dermatosis, and CARP.^2,4 Ultimately, the diagnosis of DN can be made when a history of poor hygiene is probable or elicited, and lesions can be removed with soap and water. Treatment of DN includes daily cleansing with soap and water; however, resistant lesions or extensive disease may require keratolytic agents, as in our patient.^2-4 In contrast, terra firma-forme dermatosis, which may look similar, is not due to poor hygiene, and the lesions typically are resistant to soap and water, classically requiring isopropyl alcohol for removal. Overall, maintained awareness of DN is imperative, as early diagnosis can avoid unnecessary biopsies and more complex treatment measures as well as facilitate coordination of care when additional medical or psychiatric concerns are present.

Although the diagnoses of DN and terra firma-forme dermatosis can be distinguished based on the patient’s clinical history and response to simple cleansing measures alone, the alternate diagnoses can be excluded based on different clinical distributions and response to other treatment modalities but sometimes may require clinicopathologic correlation for definitive diagnosis. Our patient had a biopsy diagnosis of psoriasiform dermatitis from an outside provider, but neither her clinical disease nor repeated histopathologic findings supported a diagnosis of psoriasis or other classic psoriasiform dermatoses such as contact dermatitis, dermatophyte/ candidal infection, seborrheic dermatitis, pityriasis rubra pilaris, pityriasis rosea, scabies, or syphilis.

It is imperative to exclude alternative diagnoses because they can have systemic implications and can misguide treatment, as was done initially with our patient. Psoriasis vulgaris in its classic form is a chronic inflammatory skin disease that manifests as sharply demarcated, erythematous plaques with overlying thick silvery scale; it has the additional histologic findings of neutrophilic spongiform pustules in the epidermis, tortuous blood vessels in the papillary dermis, and neutrophils and parakeratosis in the stratum corneum. In its benign form, AN is associated with endocrinopathies, most commonly obesity and insulin-resistant diabetes mellitus, and presents as hyperkeratotic, velvety, hyperpigmented plaques typically limited to the neck and axillae. Malignant AN spontaneously arises in association with systemic malignancy and can be extensive and generalized.⁵ Treatment of AN primarily focuses on resolution of the underlying systemic disease; however, cosmetic treatment with topical or oral retinoids may hasten resolution of cutaneous disease.⁶ Confluent and reticulated papillomatosis is characterized by reticulated hyperkeratotic plaques with a common distribution over the central and upper trunk. Unlike DN and AN, which may occur at any age, CARP typically is seen in adolescents and young adults.⁷ There is no evidence-based gold standard for the management of CARP; however, the successful use of various antibiotics, antifungals, and retinoids—alone or in combination—has been reported.⁸ Overall, compared to the other entities in the differential diagnosis, DN easily can be prevented with consistent use of soap and water and may be underreported given the asymptomatic nature of the disease and the typical patient population.

The Diagnosis: Dermatitis Neglecta

A punch biopsy of the abdomen revealed hyperkeratosis and mild papillomatosis (Figure), which can be seen in dermatitis neglecta (DN) and acanthosis nigricans (AN) as well as confluent and reticulated papillomatosis (CARP). Due to the patient’s history of mood and psychotic disorders, collateral information was obtained from the patient’s family, who reported that the patient had a depressed mood in the last few months and was not showering or caring for herself during this period. There was no additional personal or family history of skin disease. Clinical and histopathologic findings led to a diagnosis of DN. Following recommendations for daily cleansing with soap and water along with topical ammonium lactate, near-complete resolution of the rash was achieved in 3 weeks.

Dermatitis neglecta, or unwashed dermatosis, is a skin condition that occurs secondary to poor hygiene, which was first reported in 1995 by Poskitt et al.¹ Avoidance of washing in affected areas can be due to physical disability, pain after injury, neurological deficit, or psychologically induced fear or neglect. Sebum, sweat, corneocytes, and bacteria combine into compact adherent crusts of dirt, which appear as hyperkeratotic plaques with cornflakelike scale.^2,3 Despite its innate simplicity, DN is a diagnostic challenge, as it clinically and histologically mimics other dermatoses including AN, terra firmaforme dermatosis, and CARP.^2,4 Ultimately, the diagnosis of DN can be made when a history of poor hygiene is probable or elicited, and lesions can be removed with soap and water. Treatment of DN includes daily cleansing with soap and water; however, resistant lesions or extensive disease may require keratolytic agents, as in our patient.^2-4 In contrast, terra firma-forme dermatosis, which may look similar, is not due to poor hygiene, and the lesions typically are resistant to soap and water, classically requiring isopropyl alcohol for removal. Overall, maintained awareness of DN is imperative, as early diagnosis can avoid unnecessary biopsies and more complex treatment measures as well as facilitate coordination of care when additional medical or psychiatric concerns are present.

Although the diagnoses of DN and terra firma-forme dermatosis can be distinguished based on the patient’s clinical history and response to simple cleansing measures alone, the alternate diagnoses can be excluded based on different clinical distributions and response to other treatment modalities but sometimes may require clinicopathologic correlation for definitive diagnosis. Our patient had a biopsy diagnosis of psoriasiform dermatitis from an outside provider, but neither her clinical disease nor repeated histopathologic findings supported a diagnosis of psoriasis or other classic psoriasiform dermatoses such as contact dermatitis, dermatophyte/ candidal infection, seborrheic dermatitis, pityriasis rubra pilaris, pityriasis rosea, scabies, or syphilis.

It is imperative to exclude alternative diagnoses because they can have systemic implications and can misguide treatment, as was done initially with our patient. Psoriasis vulgaris in its classic form is a chronic inflammatory skin disease that manifests as sharply demarcated, erythematous plaques with overlying thick silvery scale; it has the additional histologic findings of neutrophilic spongiform pustules in the epidermis, tortuous blood vessels in the papillary dermis, and neutrophils and parakeratosis in the stratum corneum. In its benign form, AN is associated with endocrinopathies, most commonly obesity and insulin-resistant diabetes mellitus, and presents as hyperkeratotic, velvety, hyperpigmented plaques typically limited to the neck and axillae. Malignant AN spontaneously arises in association with systemic malignancy and can be extensive and generalized.⁵ Treatment of AN primarily focuses on resolution of the underlying systemic disease; however, cosmetic treatment with topical or oral retinoids may hasten resolution of cutaneous disease.⁶ Confluent and reticulated papillomatosis is characterized by reticulated hyperkeratotic plaques with a common distribution over the central and upper trunk. Unlike DN and AN, which may occur at any age, CARP typically is seen in adolescents and young adults.⁷ There is no evidence-based gold standard for the management of CARP; however, the successful use of various antibiotics, antifungals, and retinoids—alone or in combination—has been reported.⁸ Overall, compared to the other entities in the differential diagnosis, DN easily can be prevented with consistent use of soap and water and may be underreported given the asymptomatic nature of the disease and the typical patient population.

Autoeczematization (AE), or id reaction, is a disseminated eczematous reaction that occurs days or weeks after exposure to a primary stimulus, resulting from a release of antigen(s). Whitfield¹ first described AE in 1921, when he postulated that the id reaction was due to sensitization of the skin after a primary stimulus. He called it “a form of auto-intoxication derived from changes in the patient’s own tissues.”¹ The exact prevalence of id reactions is unknown; one study showed that 17% of patients with dermatophyte infections developed an id reaction, typically tinea pedis linked with vesicles on the palms.² Tinea capitis is one of the most common causes of AE in children, which is frequently misdiagnosed as a drug reaction. Approximately 37% of patients diagnosed with stasis dermatitis develop an id reaction (Figure 1). A history of contact dermatitis is common in patients presenting with AE.^2-6

Pathophysiology of Id Reactions

An abnormal immune response against autologous skin antigens may be responsible for the development of AE. Shelley⁵ postulated that hair follicles play an important role in id reactions, as Sharquie et al⁶ recently emphasized for many skin disorders. The pathogenesis of AE is uncertain, but circulating T lymphocytes play a role in this reaction. Normally, T cells are activated by a release of antigens after a primary exposure to a stimulus. However, overactivation of these T cells induces autoimmune reactions such as AE.⁷ Activated T lymphocytes express HLA-DR and IL-2 receptor, markers elevated in the peripheral blood of patients undergoing id reactions. After treatment, the levels of activated T lymphocytes decline. An increase in the number of CD25⁺ T cells and a decrease in the number of suppressor T cells in the blood may occur during an id reaction.^7-9 Keratinocytes produce proinflammatory cytokines, such as thymic stromal erythropoietin, IL-25, and IL-33, that activate T cells.^10-12 Therefore, the most likely pathogenesis of an id reaction is that T lymphocytes are activated at the primary reaction site due to proinflammatory cytokines released by keratinocytes. These activated T cells then travel systemically via hematogenous dissemination. The spread of activated T lymphocytes produces an eczematous reaction at secondary locations distant to the primary site.⁹

Clinical and Histopathological Features of Id Reactions

Clinically, AE is first evident as a vesicular dissemination that groups to form papules or nummular patches and usually is present on the legs, feet, arms, and/or trunk (Figure 2). The primary dermatitis is localized to the area that was the site of contact to the offending stimuli. This localized eczematous eruption begins with an acute or subacute onset. It has the appearance of small crusted vesicles with erythema (Figure 1). The first sign of AE is vesicles presenting near the primary site on flexural surfaces or on the hands and feet. A classic example is tinea pedis linked with vesicles on the palms and sides of the fingers, resembling dyshidrotic eczema. Sites of prior cutaneous trauma, such as dermatoses, scars, and burns, are common locations for early AE. In later stages, vesicles disseminate to the legs, arms, and trunk, where they group to form papules and nummular patches in a symmetrical pattern.^5,13-15 These lesions may be extremely pruritic. The pruritus may be so intense that it interrupts daily activities and disrupts the ability to fall or stay asleep.¹⁶

Histologically, biopsy specimens show psoriasiform spongiotic dermatitis with mononuclear cells contained in the vesicles. Interstitial edema and perivascular lymphohistiocytic infiltrates are evident. Eosinophils also may be present. This pattern is not unique toid reactions.^17-19 Although AE is a reaction pattern that may be due to a fungal or bacterial infection, the etiologic agent is not evident microscopically within the eczema itself.

Etiology of Id Reactions

Id reactions most commonly occur from either stasis dermatitis or tinea pedis, although a wide variety of other causes should be considered. Evaluation of the primary site rather than the id reaction may identify an infectious or parasitic agent. Sometimes the AE reaction is specifically named: dermatophytid with dermatophytosis, bacterid with a bacterial infectious process, and tuberculid with tuberculosis. Similarly, there may be reactions to underlying candidiasis, sporotrichosis, histoplasmosis, and other fungal infections that can cause a cutaneous id reaction.^18,20-22Mycobacterium species, Pseudomonas, Staphylococcus, and Streptococcus are bacterial causes of AE.^15,23-26 Viral infections that can cause an id reaction are herpes simplex virus and molluscum contagiosum.^27-29 Scabies, leishmaniasis, and pediculosis capitis are parasitic infections that may be etiologic.^14,30,31 In addition, noninfectious stimuli besides stasis dermatitis that can produce id reactions include medications, topical creams, tattoo ink, sutures, radiotherapy, and dyshidrotic eczema. The primary reaction to these agents is a localized dermatitis followed by the immunological response that induces a secondary reaction distant from the primary site.^17,18,32-38

Differential Diagnoses

Differential diagnoses include other types of eczema and some vesicular eruptions. Irritant contact dermatitis is another dermatosis that presents as a widespread vesicular eruption due to repetitive exposure to toxic irritants. The rash is erythematous with pustules, blisters, and crusts. It is only found in areas directly exposed to irritants, as opposed to AE, which spreads to areas distant to the primary reaction site. Irritant contact dermatitis presents with more of a burning sensation, whereas AE is more pruritic.^39,40 Allergic contact dermatitis presents with erythematous vesicles and papules and sometimes with bullae. There is edema and crust formation, which often can spread past the point of contact in later stages. Similar to AE, there is intense pruritus. However, allergic contact dermatitis most commonly is caused by exposure to metals, cosmetics, and fragrances, whereas infectious agents and stasis dermatitis are the most common causes of AE.^40,41 It may be challenging to distinguish AE from other causes of widespread eczematous dissemination. Vesicular eruptions sometimes require distinction from AE, including herpetic infections, insect bite reactions, and drug eruptions.^18,42

Treatment

The underlying condition should be treated to mitigate the inflammatory response causing the id reaction. If not skillfully orchestrated, the id reaction can reoccur. For infectious causes of AE, an antifungal, antibacterial, antiviral, or antiparasitic should be given. If stasis dermatitis is responsible for the id reaction, compression stockings and leg elevation are indicated. The id reaction itself is treated with systemic or topical corticosteroids and wet compresses if acute. The goal of these treatments is to reduce patient discomfort caused by the inflammation and pruritus.^18,43

Conclusion

Id reactions are an unusual phenomenon that commonly occurs after fungal skin infections and stasis dermatitis. T lymphocytes and keratinocytes may play a key role in this reaction, with newer research further delineating the process and possibly providing enhanced treatment options. Therapy focuses on treating the underlying condition, supplemented with corticosteroids for the autoeczema.

Autoeczematization (AE), or id reaction, is a disseminated eczematous reaction that occurs days or weeks after exposure to a primary stimulus, resulting from a release of antigen(s). Whitfield¹ first described AE in 1921, when he postulated that the id reaction was due to sensitization of the skin after a primary stimulus. He called it “a form of auto-intoxication derived from changes in the patient’s own tissues.”¹ The exact prevalence of id reactions is unknown; one study showed that 17% of patients with dermatophyte infections developed an id reaction, typically tinea pedis linked with vesicles on the palms.² Tinea capitis is one of the most common causes of AE in children, which is frequently misdiagnosed as a drug reaction. Approximately 37% of patients diagnosed with stasis dermatitis develop an id reaction (Figure 1). A history of contact dermatitis is common in patients presenting with AE.^2-6

Pathophysiology of Id Reactions

An abnormal immune response against autologous skin antigens may be responsible for the development of AE. Shelley⁵ postulated that hair follicles play an important role in id reactions, as Sharquie et al⁶ recently emphasized for many skin disorders. The pathogenesis of AE is uncertain, but circulating T lymphocytes play a role in this reaction. Normally, T cells are activated by a release of antigens after a primary exposure to a stimulus. However, overactivation of these T cells induces autoimmune reactions such as AE.⁷ Activated T lymphocytes express HLA-DR and IL-2 receptor, markers elevated in the peripheral blood of patients undergoing id reactions. After treatment, the levels of activated T lymphocytes decline. An increase in the number of CD25⁺ T cells and a decrease in the number of suppressor T cells in the blood may occur during an id reaction.^7-9 Keratinocytes produce proinflammatory cytokines, such as thymic stromal erythropoietin, IL-25, and IL-33, that activate T cells.^10-12 Therefore, the most likely pathogenesis of an id reaction is that T lymphocytes are activated at the primary reaction site due to proinflammatory cytokines released by keratinocytes. These activated T cells then travel systemically via hematogenous dissemination. The spread of activated T lymphocytes produces an eczematous reaction at secondary locations distant to the primary site.⁹

Clinical and Histopathological Features of Id Reactions

Clinically, AE is first evident as a vesicular dissemination that groups to form papules or nummular patches and usually is present on the legs, feet, arms, and/or trunk (Figure 2). The primary dermatitis is localized to the area that was the site of contact to the offending stimuli. This localized eczematous eruption begins with an acute or subacute onset. It has the appearance of small crusted vesicles with erythema (Figure 1). The first sign of AE is vesicles presenting near the primary site on flexural surfaces or on the hands and feet. A classic example is tinea pedis linked with vesicles on the palms and sides of the fingers, resembling dyshidrotic eczema. Sites of prior cutaneous trauma, such as dermatoses, scars, and burns, are common locations for early AE. In later stages, vesicles disseminate to the legs, arms, and trunk, where they group to form papules and nummular patches in a symmetrical pattern.^5,13-15 These lesions may be extremely pruritic. The pruritus may be so intense that it interrupts daily activities and disrupts the ability to fall or stay asleep.¹⁶

Histologically, biopsy specimens show psoriasiform spongiotic dermatitis with mononuclear cells contained in the vesicles. Interstitial edema and perivascular lymphohistiocytic infiltrates are evident. Eosinophils also may be present. This pattern is not unique toid reactions.^17-19 Although AE is a reaction pattern that may be due to a fungal or bacterial infection, the etiologic agent is not evident microscopically within the eczema itself.

Etiology of Id Reactions

Id reactions most commonly occur from either stasis dermatitis or tinea pedis, although a wide variety of other causes should be considered. Evaluation of the primary site rather than the id reaction may identify an infectious or parasitic agent. Sometimes the AE reaction is specifically named: dermatophytid with dermatophytosis, bacterid with a bacterial infectious process, and tuberculid with tuberculosis. Similarly, there may be reactions to underlying candidiasis, sporotrichosis, histoplasmosis, and other fungal infections that can cause a cutaneous id reaction.^18,20-22Mycobacterium species, Pseudomonas, Staphylococcus, and Streptococcus are bacterial causes of AE.^15,23-26 Viral infections that can cause an id reaction are herpes simplex virus and molluscum contagiosum.^27-29 Scabies, leishmaniasis, and pediculosis capitis are parasitic infections that may be etiologic.^14,30,31 In addition, noninfectious stimuli besides stasis dermatitis that can produce id reactions include medications, topical creams, tattoo ink, sutures, radiotherapy, and dyshidrotic eczema. The primary reaction to these agents is a localized dermatitis followed by the immunological response that induces a secondary reaction distant from the primary site.^17,18,32-38

Differential Diagnoses

Differential diagnoses include other types of eczema and some vesicular eruptions. Irritant contact dermatitis is another dermatosis that presents as a widespread vesicular eruption due to repetitive exposure to toxic irritants. The rash is erythematous with pustules, blisters, and crusts. It is only found in areas directly exposed to irritants, as opposed to AE, which spreads to areas distant to the primary reaction site. Irritant contact dermatitis presents with more of a burning sensation, whereas AE is more pruritic.^39,40 Allergic contact dermatitis presents with erythematous vesicles and papules and sometimes with bullae. There is edema and crust formation, which often can spread past the point of contact in later stages. Similar to AE, there is intense pruritus. However, allergic contact dermatitis most commonly is caused by exposure to metals, cosmetics, and fragrances, whereas infectious agents and stasis dermatitis are the most common causes of AE.^40,41 It may be challenging to distinguish AE from other causes of widespread eczematous dissemination. Vesicular eruptions sometimes require distinction from AE, including herpetic infections, insect bite reactions, and drug eruptions.^18,42

Treatment

The underlying condition should be treated to mitigate the inflammatory response causing the id reaction. If not skillfully orchestrated, the id reaction can reoccur. For infectious causes of AE, an antifungal, antibacterial, antiviral, or antiparasitic should be given. If stasis dermatitis is responsible for the id reaction, compression stockings and leg elevation are indicated. The id reaction itself is treated with systemic or topical corticosteroids and wet compresses if acute. The goal of these treatments is to reduce patient discomfort caused by the inflammation and pruritus.^18,43

Conclusion

Id reactions are an unusual phenomenon that commonly occurs after fungal skin infections and stasis dermatitis. T lymphocytes and keratinocytes may play a key role in this reaction, with newer research further delineating the process and possibly providing enhanced treatment options. Therapy focuses on treating the underlying condition, supplemented with corticosteroids for the autoeczema.

Autoeczematization (AE), or id reaction, is a disseminated eczematous reaction that occurs days or weeks after exposure to a primary stimulus, resulting from a release of antigen(s). Whitfield¹ first described AE in 1921, when he postulated that the id reaction was due to sensitization of the skin after a primary stimulus. He called it “a form of auto-intoxication derived from changes in the patient’s own tissues.”¹ The exact prevalence of id reactions is unknown; one study showed that 17% of patients with dermatophyte infections developed an id reaction, typically tinea pedis linked with vesicles on the palms.² Tinea capitis is one of the most common causes of AE in children, which is frequently misdiagnosed as a drug reaction. Approximately 37% of patients diagnosed with stasis dermatitis develop an id reaction (Figure 1). A history of contact dermatitis is common in patients presenting with AE.^2-6

Pathophysiology of Id Reactions

An abnormal immune response against autologous skin antigens may be responsible for the development of AE. Shelley⁵ postulated that hair follicles play an important role in id reactions, as Sharquie et al⁶ recently emphasized for many skin disorders. The pathogenesis of AE is uncertain, but circulating T lymphocytes play a role in this reaction. Normally, T cells are activated by a release of antigens after a primary exposure to a stimulus. However, overactivation of these T cells induces autoimmune reactions such as AE.⁷ Activated T lymphocytes express HLA-DR and IL-2 receptor, markers elevated in the peripheral blood of patients undergoing id reactions. After treatment, the levels of activated T lymphocytes decline. An increase in the number of CD25⁺ T cells and a decrease in the number of suppressor T cells in the blood may occur during an id reaction.^7-9 Keratinocytes produce proinflammatory cytokines, such as thymic stromal erythropoietin, IL-25, and IL-33, that activate T cells.^10-12 Therefore, the most likely pathogenesis of an id reaction is that T lymphocytes are activated at the primary reaction site due to proinflammatory cytokines released by keratinocytes. These activated T cells then travel systemically via hematogenous dissemination. The spread of activated T lymphocytes produces an eczematous reaction at secondary locations distant to the primary site.⁹

Clinical and Histopathological Features of Id Reactions

Clinically, AE is first evident as a vesicular dissemination that groups to form papules or nummular patches and usually is present on the legs, feet, arms, and/or trunk (Figure 2). The primary dermatitis is localized to the area that was the site of contact to the offending stimuli. This localized eczematous eruption begins with an acute or subacute onset. It has the appearance of small crusted vesicles with erythema (Figure 1). The first sign of AE is vesicles presenting near the primary site on flexural surfaces or on the hands and feet. A classic example is tinea pedis linked with vesicles on the palms and sides of the fingers, resembling dyshidrotic eczema. Sites of prior cutaneous trauma, such as dermatoses, scars, and burns, are common locations for early AE. In later stages, vesicles disseminate to the legs, arms, and trunk, where they group to form papules and nummular patches in a symmetrical pattern.^5,13-15 These lesions may be extremely pruritic. The pruritus may be so intense that it interrupts daily activities and disrupts the ability to fall or stay asleep.¹⁶

Histologically, biopsy specimens show psoriasiform spongiotic dermatitis with mononuclear cells contained in the vesicles. Interstitial edema and perivascular lymphohistiocytic infiltrates are evident. Eosinophils also may be present. This pattern is not unique toid reactions.^17-19 Although AE is a reaction pattern that may be due to a fungal or bacterial infection, the etiologic agent is not evident microscopically within the eczema itself.

Etiology of Id Reactions

Id reactions most commonly occur from either stasis dermatitis or tinea pedis, although a wide variety of other causes should be considered. Evaluation of the primary site rather than the id reaction may identify an infectious or parasitic agent. Sometimes the AE reaction is specifically named: dermatophytid with dermatophytosis, bacterid with a bacterial infectious process, and tuberculid with tuberculosis. Similarly, there may be reactions to underlying candidiasis, sporotrichosis, histoplasmosis, and other fungal infections that can cause a cutaneous id reaction.^18,20-22Mycobacterium species, Pseudomonas, Staphylococcus, and Streptococcus are bacterial causes of AE.^15,23-26 Viral infections that can cause an id reaction are herpes simplex virus and molluscum contagiosum.^27-29 Scabies, leishmaniasis, and pediculosis capitis are parasitic infections that may be etiologic.^14,30,31 In addition, noninfectious stimuli besides stasis dermatitis that can produce id reactions include medications, topical creams, tattoo ink, sutures, radiotherapy, and dyshidrotic eczema. The primary reaction to these agents is a localized dermatitis followed by the immunological response that induces a secondary reaction distant from the primary site.^17,18,32-38

Differential Diagnoses

Differential diagnoses include other types of eczema and some vesicular eruptions. Irritant contact dermatitis is another dermatosis that presents as a widespread vesicular eruption due to repetitive exposure to toxic irritants. The rash is erythematous with pustules, blisters, and crusts. It is only found in areas directly exposed to irritants, as opposed to AE, which spreads to areas distant to the primary reaction site. Irritant contact dermatitis presents with more of a burning sensation, whereas AE is more pruritic.^39,40 Allergic contact dermatitis presents with erythematous vesicles and papules and sometimes with bullae. There is edema and crust formation, which often can spread past the point of contact in later stages. Similar to AE, there is intense pruritus. However, allergic contact dermatitis most commonly is caused by exposure to metals, cosmetics, and fragrances, whereas infectious agents and stasis dermatitis are the most common causes of AE.^40,41 It may be challenging to distinguish AE from other causes of widespread eczematous dissemination. Vesicular eruptions sometimes require distinction from AE, including herpetic infections, insect bite reactions, and drug eruptions.^18,42

Treatment

The underlying condition should be treated to mitigate the inflammatory response causing the id reaction. If not skillfully orchestrated, the id reaction can reoccur. For infectious causes of AE, an antifungal, antibacterial, antiviral, or antiparasitic should be given. If stasis dermatitis is responsible for the id reaction, compression stockings and leg elevation are indicated. The id reaction itself is treated with systemic or topical corticosteroids and wet compresses if acute. The goal of these treatments is to reduce patient discomfort caused by the inflammation and pruritus.^18,43

Conclusion

Id reactions are an unusual phenomenon that commonly occurs after fungal skin infections and stasis dermatitis. T lymphocytes and keratinocytes may play a key role in this reaction, with newer research further delineating the process and possibly providing enhanced treatment options. Therapy focuses on treating the underlying condition, supplemented with corticosteroids for the autoeczema.

Plants can contribute to a variety of dermatoses. The Toxicodendron genus, which includes poison ivy, poison oak, and poison sumac, is a well-known and common cause of allergic contact dermatitis (ACD), but many other plants can cause direct or airborne contact dermatitis, especially in gardeners, florists, and farmers. This article provides an overview of different plant-related dermatoses and culprit plants as well as how these dermatoses should be diagnosed and treated.

Epidemiology

Plant dermatoses affect more than 50 million individuals each year.^1,2 In the United States, the Toxicodendron genus causes ACD in more than 70% of exposed individuals, leading to medical visits.³ An urgent care visit for a plant-related dermatitis is estimated to cost $168, while an emergency department visit can cost 3 times as much.⁴ Although less common, Compositae plants are another important culprit of plant dermatitis, particularly in gardeners, florists, and farmers. Data from the 2017-2018 North American Contact Dermatitis Group screening series (N=4947) showed sesquiterpene lactones and Compositae to be positive in 0.5% of patch-tested patients.⁵

Plant Dermatitis Classifications

Plant dermatitis can be classified into 5 main categories: ACD, mechanical irritant contact dermatitis, chemical irritant contact dermatitis, light-mediated dermatitis, and pseudophytodermatitis.⁶

Allergic contact dermatitis is an immune-mediated type IV delayed hypersensitivity reaction. The common molecular allergens in plants include phenols, α-methylene-γ-butyrolactones, quinones, terpenes, disulfides, isothiocyanates, and polyacetylenic derivatives.⁶

Plant contact dermatitis due to mechanical and chemical irritants is precipitated by multiple mechanisms, including disruption of the epidermal barrier and subsequent cytokine release from keratinocytes.⁷ Nonimmunologic contact urticaria from plants is thought to be a type of irritant reaction precipitated by mechanical or chemical trauma.⁸

Light-mediated dermatitis includes phytophotodermatitis and photoallergic contact dermatitis. Phytophotodermatitis is a phototoxic reaction triggered by exposure to both plant-derived furanocoumarin and UVA light.⁹ By contrast, photoallergic contact dermatitis is a delayed hypersensitivity reaction from prior sensitization to a light-activated antigen.¹⁰

Pseudophytodermatitis, as its name implies, is not truly mediated by an allergen or irritant intrinsic to the plant but rather by dyes, waxes, insecticides, or arthropods that inhabit the plant or are secondarily applied.⁶

Common Plant Allergens

Anacardiaceae Family
Most of the allergenic plants within the Anacardiaceae family belong to the Toxicodendron genus, which encompasses poison ivy (Toxicodendron radicans), poison oak (Toxicodendron pubescens,Toxicodendron quercifolium, Toxicodendron diversiloum), and poison sumac (Toxicodendron vernix). Poison ivy is the celebrity of the Anacardiaceae family and contributes to most cases of plant-related ACD. It is found in every state in the continental United States. Poison oak is another common culprit found in the western and southeastern United States.¹¹ Plants within the Anacardiaceae family contain an oleoresin called urushiol, which is the primary sensitizing substance. Although poison ivy and poison oak grow well in full sun to partial shade, poison sumac typically is found in damp swampy areas east of the Rocky Mountains. Most cases of ACD related to Anacardiaceae species are due to direct contact with urushiol from a Toxicodendron plant, but burning of brush containing Toxicodendron can cause airborne exposure when urushiol oil is carried by smoke particles.¹² Sensitization to Toxicodendron can cause ACD to other Anacardiaceae species such as the Japanese lacquer tree (Toxicodendron vernicifluum), mango tree (Mangifera indica), cashew tree (Anacardium occidentale), and Indian marking nut tree (Semecarpus anacardium).⁶ Cross-reactions to components of the ginkgo tree (Ginkgo biloba) also are possible.

Toxicodendron plants can be more easily identified and avoided with knowledge of their characteristic leaf patterns. The most dependable way to identify poison ivy and poison oak species is to look for plants with 3 leaves, giving rise to the common saying, “Leaves of three, leave them be.” Poison sumac plants have groups of 7 to 13 leaves arranged as pairs along a central rib. Another helpful finding is a black deposit that Toxicodendron species leave behind following trauma to the leaves. Urushiol oxidizes when exposed to air and turns into a black deposit that can be seen on damaged leaves themselves or can be demonstrated in a black spot test to verify if a plant is a Toxicodendron species. The test is performed by gathering (carefully, without direct contact) a few leaves in a paper towel and crushing them to release sap. Within minutes, the sap will turn black if the plant is indeed a Toxicodendron species.¹³Pruritic, edematous, erythematous papules, plaques, and eventual vesicles in a linear distribution are suspicious for Toxicodendron exposure. Although your pet will not develop Toxicodendron ACD, oleoresin-contaminated pets can transfer the oils to their owners after coming into contact with these plants. Toxicodendron dermatitis also can be acquired from oleoresin-contaminated fomites such as clothing and shoes worn in the garden or when hiking. Toxicodendron dermatitis can appear at different sites on the body at different times depending on the amount of oleoresin exposure as well as epidermal thickness. For example, the oleoresin can be transferred from the hands to body areas with a thinner stratum corneum (eg, genitalia) and cause subsequent dermatitis.¹

Compositae Family
The Compositae family (also known as Asteraceae) is a large plant family with more than 20,000 species, including numerous weeds, wildflowers, and vegetables. The flowers, leaves, stems, and pollens of the Compositae family are coated by cyclic esters called sesquiterpene lactones. Mitchell and Dupuis¹⁴ showed that sesquiterpene lactones are the allergens responsible for ACD to various Compositae plants, including ragweed (Ambrosia), sneezeweed (Helenium), and chrysanthemums (Chrysanthemum). Common Compositae vegetables such as lettuce (Lactuca sativa) have been reported to cause ACD in chefs, grocery store produce handlers, gardeners, and even owners of lettuce-eating pet guinea pigs and turtles.¹⁵ Similarly, artichokes (Cynara scolymus) can cause ACD in gardeners.¹⁶ Exposure to Compositae species also has been implicated in photoallergic reactions, and studies have demonstrated that some patients with chronic actinic dermatitis also have positive patch test reactions to Compositae species and/or sesquiterpene lactones.^17,18

In addition to direct contact with Compositae plants, airborne exposure to sesquiterpene lactones can cause ACD.¹⁴ The pattern of airborne contact dermatitis typically involves exposed areas such as the eyelids, central face, and/or neck. The beak sign also can be a clue to airborne contact dermatitis, which involves dermatitis of the face that spares the nasal tip and/or nasal ridge. It is thought that the beak sign may result from increased sebaceous gland concentration on the nose, which prevents penetration of allergens and irritants.¹⁹ Unlike photoallergic contact dermatitis, which also can involve the face, airborne ACD frequently involves photoprotected areas such as the submandibular chin and the upper lip. Davies and Kersey²⁰ reported the case of a groundsman who was cutting grass with dandelions (Taraxacum officinale) and was found to have associated airborne ACD of the face, neck, and forearms due to Compositae allergy. In a different setting, the aromas of chamomile (Matricaria chamomilla) have been reported to cause airborne ACD in a tea drinker.²¹ Paulsen²² found that ingestion of chamomile tea can induce systemic ACD in sensitized individuals.

Alstroemeriaceae, Liliaceae, and Primulaceae
Florists are exposed to many plant species and have a high prevalence of ACD. Thiboutot et al²³ found that 15 of 57 (26%) floral workers experienced hand dermatitis that cleared with time away from work. The Peruvian lily (Alstroemeria, Alstroemeriaceae family), which contains tuliposide A, was found to be the leading cause of sensitization.²³ Tulips (Tulipa, Liliaceae family), as the flower name suggests, also contain tuliposide A, which along with mechanical irritation from the course tecta fibers on the bulbs lead to a dermatitis known as tulip fingers.^24,25 Poison primrose (Primula obconica, Primulaceae family), cultivated for its highly colorful flowers, contains the contact allergen primin.⁶ A common clinical presentation of ACD for any of these culprit flowers is localized dermatitis of the thumb and index finger in a florist or gardener.

Plants That Cause Irritant Reactions

Cactuses
Although the long spines of the Cactaceae family of cactuses is a warning for passersby, it is the small and nearly invisible barbed hairs (glochids) that inflict a more dramatic cutaneous reaction. The prickly pear cactus (Opuntia species) is a good example of such a plant, as its glochids cause mechanical irritation but also can become embedded in the skin and result in subcutaneous granulomas known as sabra dermatitis.²⁶

Stinging Nettle
The dermatologic term urticaria owes its namesake to the stinging nettle plant, which comes from the family Urticaceae. The stinging nettle has small hairs on its leaves, referred to as stinging trichomes, which have needlelike tips that pierce the skin and inject a mix of histamine, formic acid, and acetylcholine, causing a pruritic dermatitis that may last up to 12 hours.²⁷ The plant is found worldwide and is a common weed in North America.

Phytophotodermatitis

Lemons and limes (Rutaceae family) are common culprits of phytophotodermatitis, often causing what is known as a margarita burn after outdoor consumption or preparation of this tasty citrus beverage.²⁸ An accidental spray of lime juice on the skin while adding it to a beer, guacamole, salsa, or any other food or beverage also can cause phytophotodermatitis.^29-31 Although the juice of lemons and limes contains psoralens, the rind can contain a 6- to 186-fold increased concentration.³² Psoralen is the photoactive agent in Rutaceae plants that intercalates in double-stranded DNA and promotes intrastrand cross-links when exposed to UVA light, which ultimately leads to dermatitis.⁹ Phytophotodermatitis commonly causes erythema, edema, and painful bullae on sun-exposed areas and classically heals with hyperpigmentation.

Pseudophytodermatitis can occur in grain farmers and harvesters who handle wheat and/or barley and incidentally come in contact with insects and chemicals on the plant material. Pseudophytodermatitis from mites in the wheat and/or barley plant can occur at harvest time when contact with the plant material is high. Insects such as the North American itch mite (Pediculoides ventricosus) can cause petechiae, wheals, and pustules. In addition, insecticides such as malathion and arsenical sprays that are applied to plant leaves can cause pseudophytodermatitis, which may be initially diagnosed as dermatitis to the plant itself.⁶

Patch Testing to Plants

When a patient presents with recurrent or persistent dermatitis and a plant contact allergen is suspected, patch testing is indicated. Most comprehensive patch test series contain various plant allergens, such as sesquiterpene lactones, Compositae mix, and limonene hydroperoxides, and patch testing to a specialized plant series may be necessary. Poison ivy/oak/sumac allergens typically are not included in patch test series because of the high prevalence of allergic reactions to these chemicals and the likelihood of sensitization when patch testing with urushiol. Compositae contact sensitization can be difficult to diagnose because neither sesquiterpene lactone mix 0.1% nor parthenolide 0.1% are sensitive enough to pick up all Compositae allergies.^33,34 Paulsen and Andersen³⁴ proposed that if Compositae sensitization is suspected, testing should include sesquiterpene lactone, parthenolide, and Compositae mix II 2.5%, as well as other potential Compositae allergens based on the patient’s history.³⁴

Because plants can have geographic variability and contain potentially unknown allergens,³⁵ testing to plant components may increase the diagnostic yield of patch testing. Dividing the plant into component parts (ie, stem, bulb, leaf, flower) is helpful, as different components have different allergen concentrations. It is important to consult expert resources before proceeding with plant component patch testing because irritant reactions are frequent and may confound the testing.³⁶

Prevention and Treatment

For all plant dermatoses, the mainstay of prevention is to avoid contact with the offending plant material. Gloves can be an important protective tool for plant dermatitis prevention; the correct material depends on the plant species being handled. Rubber gloves should not be worn to protect against Toxicodendron plants since the catechols in urushiol are soluble in rubber; vinyl gloves should be worn instead.⁶ Marks³⁷ found that tuliposide A, the allergen in the Peruvian lily (Alstroemeria), penetrates both vinyl and latex gloves; it does not penetrate nitrile gloves. If exposed, the risk of dermatitis can be decreased if the allergen is washed away with soap and water as soon as possible. Some allergens such as Toxicodendron are absorbed quickly and need to be washed off within 10 minutes of exposure.⁶ Importantly, exposed gardening gloves may continue to perpetuate ACD if the allergen is not also washed off the gloves themselves.

For light-mediated dermatoses, sun avoidance or use of an effective sunscreen can reduce symptoms in an individual who has already been exposed.¹⁰ UVA light activates psoralen-mediated dermatitis but not until 30 to 120 minutes after absorption into the skin.³⁸

Barrier creams are thought to be protective against plant ACD through a variety of mechanisms. The cream itself is meant to reduce skin contact to an allergen or irritant. Additionally, barrier creams contain active ingredients such as silicone, hydrocarbons, and aluminum chlorohydrate, which are thought to trap or transform offending agents before contacting the skin. When contact with a Toxicodendron species is anticipated, Marks et al³⁹ found that dermatitis was absent or significantly reduced when 144 patients were pretreated with quaternium-18 bentonite lotion 5% (P<.0001).

Although allergen avoidance and use of gloves and barrier creams are the mainstays of preventing plant dermatoses, treatment often is required to control postexposure symptoms. For all plant dermatoses, topical corticosteroids can be used to reduce inflammation and pruritus. In some cases, systemic steroids may be necessary. To prevent rebound of dermatitis, patients often require a 3-week or longer course of oral steroids to quell the reaction, particularly if the dermatitis is vigorous or an id reaction is present.⁴⁰ Antihistamines and cold compresses also can provide symptomatic relief.

Final Interpretation

Plants can cause a variety of dermatoses. Although Toxicodendron plants are the most frequent cause of ACD, it is important to keep in mind that florists, gardeners, and farmers are exposed to a large variety of allergens, irritants, and phototoxic agents that cause dermatoses as well. Confirmation of plant-induced ACD involves patch testing against suspected species. Prevention involves use of appropriate barriers and avoidance of implicated plants. Treatment includes topical steroids, antihistamines, and prednisone.

Plants can contribute to a variety of dermatoses. The Toxicodendron genus, which includes poison ivy, poison oak, and poison sumac, is a well-known and common cause of allergic contact dermatitis (ACD), but many other plants can cause direct or airborne contact dermatitis, especially in gardeners, florists, and farmers. This article provides an overview of different plant-related dermatoses and culprit plants as well as how these dermatoses should be diagnosed and treated.

Epidemiology

Plant dermatoses affect more than 50 million individuals each year.^1,2 In the United States, the Toxicodendron genus causes ACD in more than 70% of exposed individuals, leading to medical visits.³ An urgent care visit for a plant-related dermatitis is estimated to cost $168, while an emergency department visit can cost 3 times as much.⁴ Although less common, Compositae plants are another important culprit of plant dermatitis, particularly in gardeners, florists, and farmers. Data from the 2017-2018 North American Contact Dermatitis Group screening series (N=4947) showed sesquiterpene lactones and Compositae to be positive in 0.5% of patch-tested patients.⁵

Plant Dermatitis Classifications

Plant dermatitis can be classified into 5 main categories: ACD, mechanical irritant contact dermatitis, chemical irritant contact dermatitis, light-mediated dermatitis, and pseudophytodermatitis.⁶

Allergic contact dermatitis is an immune-mediated type IV delayed hypersensitivity reaction. The common molecular allergens in plants include phenols, α-methylene-γ-butyrolactones, quinones, terpenes, disulfides, isothiocyanates, and polyacetylenic derivatives.⁶

Plant contact dermatitis due to mechanical and chemical irritants is precipitated by multiple mechanisms, including disruption of the epidermal barrier and subsequent cytokine release from keratinocytes.⁷ Nonimmunologic contact urticaria from plants is thought to be a type of irritant reaction precipitated by mechanical or chemical trauma.⁸

Light-mediated dermatitis includes phytophotodermatitis and photoallergic contact dermatitis. Phytophotodermatitis is a phototoxic reaction triggered by exposure to both plant-derived furanocoumarin and UVA light.⁹ By contrast, photoallergic contact dermatitis is a delayed hypersensitivity reaction from prior sensitization to a light-activated antigen.¹⁰

Pseudophytodermatitis, as its name implies, is not truly mediated by an allergen or irritant intrinsic to the plant but rather by dyes, waxes, insecticides, or arthropods that inhabit the plant or are secondarily applied.⁶

Common Plant Allergens

Anacardiaceae Family
Most of the allergenic plants within the Anacardiaceae family belong to the Toxicodendron genus, which encompasses poison ivy (Toxicodendron radicans), poison oak (Toxicodendron pubescens,Toxicodendron quercifolium, Toxicodendron diversiloum), and poison sumac (Toxicodendron vernix). Poison ivy is the celebrity of the Anacardiaceae family and contributes to most cases of plant-related ACD. It is found in every state in the continental United States. Poison oak is another common culprit found in the western and southeastern United States.¹¹ Plants within the Anacardiaceae family contain an oleoresin called urushiol, which is the primary sensitizing substance. Although poison ivy and poison oak grow well in full sun to partial shade, poison sumac typically is found in damp swampy areas east of the Rocky Mountains. Most cases of ACD related to Anacardiaceae species are due to direct contact with urushiol from a Toxicodendron plant, but burning of brush containing Toxicodendron can cause airborne exposure when urushiol oil is carried by smoke particles.¹² Sensitization to Toxicodendron can cause ACD to other Anacardiaceae species such as the Japanese lacquer tree (Toxicodendron vernicifluum), mango tree (Mangifera indica), cashew tree (Anacardium occidentale), and Indian marking nut tree (Semecarpus anacardium).⁶ Cross-reactions to components of the ginkgo tree (Ginkgo biloba) also are possible.

Toxicodendron plants can be more easily identified and avoided with knowledge of their characteristic leaf patterns. The most dependable way to identify poison ivy and poison oak species is to look for plants with 3 leaves, giving rise to the common saying, “Leaves of three, leave them be.” Poison sumac plants have groups of 7 to 13 leaves arranged as pairs along a central rib. Another helpful finding is a black deposit that Toxicodendron species leave behind following trauma to the leaves. Urushiol oxidizes when exposed to air and turns into a black deposit that can be seen on damaged leaves themselves or can be demonstrated in a black spot test to verify if a plant is a Toxicodendron species. The test is performed by gathering (carefully, without direct contact) a few leaves in a paper towel and crushing them to release sap. Within minutes, the sap will turn black if the plant is indeed a Toxicodendron species.¹³Pruritic, edematous, erythematous papules, plaques, and eventual vesicles in a linear distribution are suspicious for Toxicodendron exposure. Although your pet will not develop Toxicodendron ACD, oleoresin-contaminated pets can transfer the oils to their owners after coming into contact with these plants. Toxicodendron dermatitis also can be acquired from oleoresin-contaminated fomites such as clothing and shoes worn in the garden or when hiking. Toxicodendron dermatitis can appear at different sites on the body at different times depending on the amount of oleoresin exposure as well as epidermal thickness. For example, the oleoresin can be transferred from the hands to body areas with a thinner stratum corneum (eg, genitalia) and cause subsequent dermatitis.¹

Compositae Family
The Compositae family (also known as Asteraceae) is a large plant family with more than 20,000 species, including numerous weeds, wildflowers, and vegetables. The flowers, leaves, stems, and pollens of the Compositae family are coated by cyclic esters called sesquiterpene lactones. Mitchell and Dupuis¹⁴ showed that sesquiterpene lactones are the allergens responsible for ACD to various Compositae plants, including ragweed (Ambrosia), sneezeweed (Helenium), and chrysanthemums (Chrysanthemum). Common Compositae vegetables such as lettuce (Lactuca sativa) have been reported to cause ACD in chefs, grocery store produce handlers, gardeners, and even owners of lettuce-eating pet guinea pigs and turtles.¹⁵ Similarly, artichokes (Cynara scolymus) can cause ACD in gardeners.¹⁶ Exposure to Compositae species also has been implicated in photoallergic reactions, and studies have demonstrated that some patients with chronic actinic dermatitis also have positive patch test reactions to Compositae species and/or sesquiterpene lactones.^17,18

In addition to direct contact with Compositae plants, airborne exposure to sesquiterpene lactones can cause ACD.¹⁴ The pattern of airborne contact dermatitis typically involves exposed areas such as the eyelids, central face, and/or neck. The beak sign also can be a clue to airborne contact dermatitis, which involves dermatitis of the face that spares the nasal tip and/or nasal ridge. It is thought that the beak sign may result from increased sebaceous gland concentration on the nose, which prevents penetration of allergens and irritants.¹⁹ Unlike photoallergic contact dermatitis, which also can involve the face, airborne ACD frequently involves photoprotected areas such as the submandibular chin and the upper lip. Davies and Kersey²⁰ reported the case of a groundsman who was cutting grass with dandelions (Taraxacum officinale) and was found to have associated airborne ACD of the face, neck, and forearms due to Compositae allergy. In a different setting, the aromas of chamomile (Matricaria chamomilla) have been reported to cause airborne ACD in a tea drinker.²¹ Paulsen²² found that ingestion of chamomile tea can induce systemic ACD in sensitized individuals.

Alstroemeriaceae, Liliaceae, and Primulaceae
Florists are exposed to many plant species and have a high prevalence of ACD. Thiboutot et al²³ found that 15 of 57 (26%) floral workers experienced hand dermatitis that cleared with time away from work. The Peruvian lily (Alstroemeria, Alstroemeriaceae family), which contains tuliposide A, was found to be the leading cause of sensitization.²³ Tulips (Tulipa, Liliaceae family), as the flower name suggests, also contain tuliposide A, which along with mechanical irritation from the course tecta fibers on the bulbs lead to a dermatitis known as tulip fingers.^24,25 Poison primrose (Primula obconica, Primulaceae family), cultivated for its highly colorful flowers, contains the contact allergen primin.⁶ A common clinical presentation of ACD for any of these culprit flowers is localized dermatitis of the thumb and index finger in a florist or gardener.

Plants That Cause Irritant Reactions

Cactuses
Although the long spines of the Cactaceae family of cactuses is a warning for passersby, it is the small and nearly invisible barbed hairs (glochids) that inflict a more dramatic cutaneous reaction. The prickly pear cactus (Opuntia species) is a good example of such a plant, as its glochids cause mechanical irritation but also can become embedded in the skin and result in subcutaneous granulomas known as sabra dermatitis.²⁶

Stinging Nettle
The dermatologic term urticaria owes its namesake to the stinging nettle plant, which comes from the family Urticaceae. The stinging nettle has small hairs on its leaves, referred to as stinging trichomes, which have needlelike tips that pierce the skin and inject a mix of histamine, formic acid, and acetylcholine, causing a pruritic dermatitis that may last up to 12 hours.²⁷ The plant is found worldwide and is a common weed in North America.

Phytophotodermatitis

Lemons and limes (Rutaceae family) are common culprits of phytophotodermatitis, often causing what is known as a margarita burn after outdoor consumption or preparation of this tasty citrus beverage.²⁸ An accidental spray of lime juice on the skin while adding it to a beer, guacamole, salsa, or any other food or beverage also can cause phytophotodermatitis.^29-31 Although the juice of lemons and limes contains psoralens, the rind can contain a 6- to 186-fold increased concentration.³² Psoralen is the photoactive agent in Rutaceae plants that intercalates in double-stranded DNA and promotes intrastrand cross-links when exposed to UVA light, which ultimately leads to dermatitis.⁹ Phytophotodermatitis commonly causes erythema, edema, and painful bullae on sun-exposed areas and classically heals with hyperpigmentation.

Pseudophytodermatitis can occur in grain farmers and harvesters who handle wheat and/or barley and incidentally come in contact with insects and chemicals on the plant material. Pseudophytodermatitis from mites in the wheat and/or barley plant can occur at harvest time when contact with the plant material is high. Insects such as the North American itch mite (Pediculoides ventricosus) can cause petechiae, wheals, and pustules. In addition, insecticides such as malathion and arsenical sprays that are applied to plant leaves can cause pseudophytodermatitis, which may be initially diagnosed as dermatitis to the plant itself.⁶

Patch Testing to Plants

When a patient presents with recurrent or persistent dermatitis and a plant contact allergen is suspected, patch testing is indicated. Most comprehensive patch test series contain various plant allergens, such as sesquiterpene lactones, Compositae mix, and limonene hydroperoxides, and patch testing to a specialized plant series may be necessary. Poison ivy/oak/sumac allergens typically are not included in patch test series because of the high prevalence of allergic reactions to these chemicals and the likelihood of sensitization when patch testing with urushiol. Compositae contact sensitization can be difficult to diagnose because neither sesquiterpene lactone mix 0.1% nor parthenolide 0.1% are sensitive enough to pick up all Compositae allergies.^33,34 Paulsen and Andersen³⁴ proposed that if Compositae sensitization is suspected, testing should include sesquiterpene lactone, parthenolide, and Compositae mix II 2.5%, as well as other potential Compositae allergens based on the patient’s history.³⁴

Because plants can have geographic variability and contain potentially unknown allergens,³⁵ testing to plant components may increase the diagnostic yield of patch testing. Dividing the plant into component parts (ie, stem, bulb, leaf, flower) is helpful, as different components have different allergen concentrations. It is important to consult expert resources before proceeding with plant component patch testing because irritant reactions are frequent and may confound the testing.³⁶

Prevention and Treatment

For all plant dermatoses, the mainstay of prevention is to avoid contact with the offending plant material. Gloves can be an important protective tool for plant dermatitis prevention; the correct material depends on the plant species being handled. Rubber gloves should not be worn to protect against Toxicodendron plants since the catechols in urushiol are soluble in rubber; vinyl gloves should be worn instead.⁶ Marks³⁷ found that tuliposide A, the allergen in the Peruvian lily (Alstroemeria), penetrates both vinyl and latex gloves; it does not penetrate nitrile gloves. If exposed, the risk of dermatitis can be decreased if the allergen is washed away with soap and water as soon as possible. Some allergens such as Toxicodendron are absorbed quickly and need to be washed off within 10 minutes of exposure.⁶ Importantly, exposed gardening gloves may continue to perpetuate ACD if the allergen is not also washed off the gloves themselves.

For light-mediated dermatoses, sun avoidance or use of an effective sunscreen can reduce symptoms in an individual who has already been exposed.¹⁰ UVA light activates psoralen-mediated dermatitis but not until 30 to 120 minutes after absorption into the skin.³⁸

Barrier creams are thought to be protective against plant ACD through a variety of mechanisms. The cream itself is meant to reduce skin contact to an allergen or irritant. Additionally, barrier creams contain active ingredients such as silicone, hydrocarbons, and aluminum chlorohydrate, which are thought to trap or transform offending agents before contacting the skin. When contact with a Toxicodendron species is anticipated, Marks et al³⁹ found that dermatitis was absent or significantly reduced when 144 patients were pretreated with quaternium-18 bentonite lotion 5% (P<.0001).

Although allergen avoidance and use of gloves and barrier creams are the mainstays of preventing plant dermatoses, treatment often is required to control postexposure symptoms. For all plant dermatoses, topical corticosteroids can be used to reduce inflammation and pruritus. In some cases, systemic steroids may be necessary. To prevent rebound of dermatitis, patients often require a 3-week or longer course of oral steroids to quell the reaction, particularly if the dermatitis is vigorous or an id reaction is present.⁴⁰ Antihistamines and cold compresses also can provide symptomatic relief.

Final Interpretation

Plants can cause a variety of dermatoses. Although Toxicodendron plants are the most frequent cause of ACD, it is important to keep in mind that florists, gardeners, and farmers are exposed to a large variety of allergens, irritants, and phototoxic agents that cause dermatoses as well. Confirmation of plant-induced ACD involves patch testing against suspected species. Prevention involves use of appropriate barriers and avoidance of implicated plants. Treatment includes topical steroids, antihistamines, and prednisone.

Plants can contribute to a variety of dermatoses. The Toxicodendron genus, which includes poison ivy, poison oak, and poison sumac, is a well-known and common cause of allergic contact dermatitis (ACD), but many other plants can cause direct or airborne contact dermatitis, especially in gardeners, florists, and farmers. This article provides an overview of different plant-related dermatoses and culprit plants as well as how these dermatoses should be diagnosed and treated.

Epidemiology

Plant dermatoses affect more than 50 million individuals each year.^1,2 In the United States, the Toxicodendron genus causes ACD in more than 70% of exposed individuals, leading to medical visits.³ An urgent care visit for a plant-related dermatitis is estimated to cost $168, while an emergency department visit can cost 3 times as much.⁴ Although less common, Compositae plants are another important culprit of plant dermatitis, particularly in gardeners, florists, and farmers. Data from the 2017-2018 North American Contact Dermatitis Group screening series (N=4947) showed sesquiterpene lactones and Compositae to be positive in 0.5% of patch-tested patients.⁵

Plant Dermatitis Classifications

Plant dermatitis can be classified into 5 main categories: ACD, mechanical irritant contact dermatitis, chemical irritant contact dermatitis, light-mediated dermatitis, and pseudophytodermatitis.⁶

Allergic contact dermatitis is an immune-mediated type IV delayed hypersensitivity reaction. The common molecular allergens in plants include phenols, α-methylene-γ-butyrolactones, quinones, terpenes, disulfides, isothiocyanates, and polyacetylenic derivatives.⁶

Plant contact dermatitis due to mechanical and chemical irritants is precipitated by multiple mechanisms, including disruption of the epidermal barrier and subsequent cytokine release from keratinocytes.⁷ Nonimmunologic contact urticaria from plants is thought to be a type of irritant reaction precipitated by mechanical or chemical trauma.⁸

Light-mediated dermatitis includes phytophotodermatitis and photoallergic contact dermatitis. Phytophotodermatitis is a phototoxic reaction triggered by exposure to both plant-derived furanocoumarin and UVA light.⁹ By contrast, photoallergic contact dermatitis is a delayed hypersensitivity reaction from prior sensitization to a light-activated antigen.¹⁰

Pseudophytodermatitis, as its name implies, is not truly mediated by an allergen or irritant intrinsic to the plant but rather by dyes, waxes, insecticides, or arthropods that inhabit the plant or are secondarily applied.⁶

Common Plant Allergens

Anacardiaceae Family
Most of the allergenic plants within the Anacardiaceae family belong to the Toxicodendron genus, which encompasses poison ivy (Toxicodendron radicans), poison oak (Toxicodendron pubescens,Toxicodendron quercifolium, Toxicodendron diversiloum), and poison sumac (Toxicodendron vernix). Poison ivy is the celebrity of the Anacardiaceae family and contributes to most cases of plant-related ACD. It is found in every state in the continental United States. Poison oak is another common culprit found in the western and southeastern United States.¹¹ Plants within the Anacardiaceae family contain an oleoresin called urushiol, which is the primary sensitizing substance. Although poison ivy and poison oak grow well in full sun to partial shade, poison sumac typically is found in damp swampy areas east of the Rocky Mountains. Most cases of ACD related to Anacardiaceae species are due to direct contact with urushiol from a Toxicodendron plant, but burning of brush containing Toxicodendron can cause airborne exposure when urushiol oil is carried by smoke particles.¹² Sensitization to Toxicodendron can cause ACD to other Anacardiaceae species such as the Japanese lacquer tree (Toxicodendron vernicifluum), mango tree (Mangifera indica), cashew tree (Anacardium occidentale), and Indian marking nut tree (Semecarpus anacardium).⁶ Cross-reactions to components of the ginkgo tree (Ginkgo biloba) also are possible.

Toxicodendron plants can be more easily identified and avoided with knowledge of their characteristic leaf patterns. The most dependable way to identify poison ivy and poison oak species is to look for plants with 3 leaves, giving rise to the common saying, “Leaves of three, leave them be.” Poison sumac plants have groups of 7 to 13 leaves arranged as pairs along a central rib. Another helpful finding is a black deposit that Toxicodendron species leave behind following trauma to the leaves. Urushiol oxidizes when exposed to air and turns into a black deposit that can be seen on damaged leaves themselves or can be demonstrated in a black spot test to verify if a plant is a Toxicodendron species. The test is performed by gathering (carefully, without direct contact) a few leaves in a paper towel and crushing them to release sap. Within minutes, the sap will turn black if the plant is indeed a Toxicodendron species.¹³Pruritic, edematous, erythematous papules, plaques, and eventual vesicles in a linear distribution are suspicious for Toxicodendron exposure. Although your pet will not develop Toxicodendron ACD, oleoresin-contaminated pets can transfer the oils to their owners after coming into contact with these plants. Toxicodendron dermatitis also can be acquired from oleoresin-contaminated fomites such as clothing and shoes worn in the garden or when hiking. Toxicodendron dermatitis can appear at different sites on the body at different times depending on the amount of oleoresin exposure as well as epidermal thickness. For example, the oleoresin can be transferred from the hands to body areas with a thinner stratum corneum (eg, genitalia) and cause subsequent dermatitis.¹

Compositae Family
The Compositae family (also known as Asteraceae) is a large plant family with more than 20,000 species, including numerous weeds, wildflowers, and vegetables. The flowers, leaves, stems, and pollens of the Compositae family are coated by cyclic esters called sesquiterpene lactones. Mitchell and Dupuis¹⁴ showed that sesquiterpene lactones are the allergens responsible for ACD to various Compositae plants, including ragweed (Ambrosia), sneezeweed (Helenium), and chrysanthemums (Chrysanthemum). Common Compositae vegetables such as lettuce (Lactuca sativa) have been reported to cause ACD in chefs, grocery store produce handlers, gardeners, and even owners of lettuce-eating pet guinea pigs and turtles.¹⁵ Similarly, artichokes (Cynara scolymus) can cause ACD in gardeners.¹⁶ Exposure to Compositae species also has been implicated in photoallergic reactions, and studies have demonstrated that some patients with chronic actinic dermatitis also have positive patch test reactions to Compositae species and/or sesquiterpene lactones.^17,18

In addition to direct contact with Compositae plants, airborne exposure to sesquiterpene lactones can cause ACD.¹⁴ The pattern of airborne contact dermatitis typically involves exposed areas such as the eyelids, central face, and/or neck. The beak sign also can be a clue to airborne contact dermatitis, which involves dermatitis of the face that spares the nasal tip and/or nasal ridge. It is thought that the beak sign may result from increased sebaceous gland concentration on the nose, which prevents penetration of allergens and irritants.¹⁹ Unlike photoallergic contact dermatitis, which also can involve the face, airborne ACD frequently involves photoprotected areas such as the submandibular chin and the upper lip. Davies and Kersey²⁰ reported the case of a groundsman who was cutting grass with dandelions (Taraxacum officinale) and was found to have associated airborne ACD of the face, neck, and forearms due to Compositae allergy. In a different setting, the aromas of chamomile (Matricaria chamomilla) have been reported to cause airborne ACD in a tea drinker.²¹ Paulsen²² found that ingestion of chamomile tea can induce systemic ACD in sensitized individuals.

Alstroemeriaceae, Liliaceae, and Primulaceae
Florists are exposed to many plant species and have a high prevalence of ACD. Thiboutot et al²³ found that 15 of 57 (26%) floral workers experienced hand dermatitis that cleared with time away from work. The Peruvian lily (Alstroemeria, Alstroemeriaceae family), which contains tuliposide A, was found to be the leading cause of sensitization.²³ Tulips (Tulipa, Liliaceae family), as the flower name suggests, also contain tuliposide A, which along with mechanical irritation from the course tecta fibers on the bulbs lead to a dermatitis known as tulip fingers.^24,25 Poison primrose (Primula obconica, Primulaceae family), cultivated for its highly colorful flowers, contains the contact allergen primin.⁶ A common clinical presentation of ACD for any of these culprit flowers is localized dermatitis of the thumb and index finger in a florist or gardener.

Plants That Cause Irritant Reactions

Cactuses
Although the long spines of the Cactaceae family of cactuses is a warning for passersby, it is the small and nearly invisible barbed hairs (glochids) that inflict a more dramatic cutaneous reaction. The prickly pear cactus (Opuntia species) is a good example of such a plant, as its glochids cause mechanical irritation but also can become embedded in the skin and result in subcutaneous granulomas known as sabra dermatitis.²⁶

Stinging Nettle
The dermatologic term urticaria owes its namesake to the stinging nettle plant, which comes from the family Urticaceae. The stinging nettle has small hairs on its leaves, referred to as stinging trichomes, which have needlelike tips that pierce the skin and inject a mix of histamine, formic acid, and acetylcholine, causing a pruritic dermatitis that may last up to 12 hours.²⁷ The plant is found worldwide and is a common weed in North America.

Phytophotodermatitis

Lemons and limes (Rutaceae family) are common culprits of phytophotodermatitis, often causing what is known as a margarita burn after outdoor consumption or preparation of this tasty citrus beverage.²⁸ An accidental spray of lime juice on the skin while adding it to a beer, guacamole, salsa, or any other food or beverage also can cause phytophotodermatitis.^29-31 Although the juice of lemons and limes contains psoralens, the rind can contain a 6- to 186-fold increased concentration.³² Psoralen is the photoactive agent in Rutaceae plants that intercalates in double-stranded DNA and promotes intrastrand cross-links when exposed to UVA light, which ultimately leads to dermatitis.⁹ Phytophotodermatitis commonly causes erythema, edema, and painful bullae on sun-exposed areas and classically heals with hyperpigmentation.

Pseudophytodermatitis can occur in grain farmers and harvesters who handle wheat and/or barley and incidentally come in contact with insects and chemicals on the plant material. Pseudophytodermatitis from mites in the wheat and/or barley plant can occur at harvest time when contact with the plant material is high. Insects such as the North American itch mite (Pediculoides ventricosus) can cause petechiae, wheals, and pustules. In addition, insecticides such as malathion and arsenical sprays that are applied to plant leaves can cause pseudophytodermatitis, which may be initially diagnosed as dermatitis to the plant itself.⁶

Patch Testing to Plants

When a patient presents with recurrent or persistent dermatitis and a plant contact allergen is suspected, patch testing is indicated. Most comprehensive patch test series contain various plant allergens, such as sesquiterpene lactones, Compositae mix, and limonene hydroperoxides, and patch testing to a specialized plant series may be necessary. Poison ivy/oak/sumac allergens typically are not included in patch test series because of the high prevalence of allergic reactions to these chemicals and the likelihood of sensitization when patch testing with urushiol. Compositae contact sensitization can be difficult to diagnose because neither sesquiterpene lactone mix 0.1% nor parthenolide 0.1% are sensitive enough to pick up all Compositae allergies.^33,34 Paulsen and Andersen³⁴ proposed that if Compositae sensitization is suspected, testing should include sesquiterpene lactone, parthenolide, and Compositae mix II 2.5%, as well as other potential Compositae allergens based on the patient’s history.³⁴

Because plants can have geographic variability and contain potentially unknown allergens,³⁵ testing to plant components may increase the diagnostic yield of patch testing. Dividing the plant into component parts (ie, stem, bulb, leaf, flower) is helpful, as different components have different allergen concentrations. It is important to consult expert resources before proceeding with plant component patch testing because irritant reactions are frequent and may confound the testing.³⁶

Prevention and Treatment

For all plant dermatoses, the mainstay of prevention is to avoid contact with the offending plant material. Gloves can be an important protective tool for plant dermatitis prevention; the correct material depends on the plant species being handled. Rubber gloves should not be worn to protect against Toxicodendron plants since the catechols in urushiol are soluble in rubber; vinyl gloves should be worn instead.⁶ Marks³⁷ found that tuliposide A, the allergen in the Peruvian lily (Alstroemeria), penetrates both vinyl and latex gloves; it does not penetrate nitrile gloves. If exposed, the risk of dermatitis can be decreased if the allergen is washed away with soap and water as soon as possible. Some allergens such as Toxicodendron are absorbed quickly and need to be washed off within 10 minutes of exposure.⁶ Importantly, exposed gardening gloves may continue to perpetuate ACD if the allergen is not also washed off the gloves themselves.

For light-mediated dermatoses, sun avoidance or use of an effective sunscreen can reduce symptoms in an individual who has already been exposed.¹⁰ UVA light activates psoralen-mediated dermatitis but not until 30 to 120 minutes after absorption into the skin.³⁸

Barrier creams are thought to be protective against plant ACD through a variety of mechanisms. The cream itself is meant to reduce skin contact to an allergen or irritant. Additionally, barrier creams contain active ingredients such as silicone, hydrocarbons, and aluminum chlorohydrate, which are thought to trap or transform offending agents before contacting the skin. When contact with a Toxicodendron species is anticipated, Marks et al³⁹ found that dermatitis was absent or significantly reduced when 144 patients were pretreated with quaternium-18 bentonite lotion 5% (P<.0001).

Although allergen avoidance and use of gloves and barrier creams are the mainstays of preventing plant dermatoses, treatment often is required to control postexposure symptoms. For all plant dermatoses, topical corticosteroids can be used to reduce inflammation and pruritus. In some cases, systemic steroids may be necessary. To prevent rebound of dermatitis, patients often require a 3-week or longer course of oral steroids to quell the reaction, particularly if the dermatitis is vigorous or an id reaction is present.⁴⁰ Antihistamines and cold compresses also can provide symptomatic relief.

Final Interpretation

Plants can cause a variety of dermatoses. Although Toxicodendron plants are the most frequent cause of ACD, it is important to keep in mind that florists, gardeners, and farmers are exposed to a large variety of allergens, irritants, and phototoxic agents that cause dermatoses as well. Confirmation of plant-induced ACD involves patch testing against suspected species. Prevention involves use of appropriate barriers and avoidance of implicated plants. Treatment includes topical steroids, antihistamines, and prednisone.

Sea cucumbers—commonly known as trepang in Indonesia, namako in Japan, and hai shen in China, where they are treasured as a food delicacy—are sea creatures belonging to the phylum Echinodermata, class Holothuridea, and family Cucumariidae . ^1,2 They are an integral part of a variety of marine habitats, serving as cleaners as they filter through sediment for nutrients. They can be found on the ocean floor under hundreds of feet of water or in shallow sandy waters along the coast, but they most commonly are found living among coral reefs. Sea cucumbers look just as they sound—shaped like cucumbers or sausages, ranging from under 1 inch to upwards of 6 feet in length depending on the specific species (Figure 1). They have a group of tentacles around the mouth used for filtering sediment, and they move about the ocean floor on tubular feet protruding through the body wall, similar to a sea star.

Beneficial Properties and Cultural Relevance

Although more than 1200 species of sea cucumbers have been identified thus far, only about 20 of these are edible.² The most common of the edible species is Stichopus japonicus, which can be found off the coasts of Korea, China, Japan, and Russia. This particular species most commonly is used in traditional dishes and is divided into 3 groups based on the color: red, green, or black. The price and taste of sea cucumbers varies based on the color, with red being the most expensive.² The body wall of the sea cucumber is cleaned, repeatedly boiled, and dried until edible. It is considered a delicacy, not only in food but also in pharmaceutical forms, as it is comprised of a variety of vitamins, minerals, and other nutrients that are thought to provide anticancer, anticoagulant, antioxidant, antifungal, and anti-inflammatory properties. Components of the body wall include collagen, mucopolysaccharides, peptides, gelatin, glycosaminoglycans, glycosides (including various holotoxins), hydroxylates, saponins, and fatty acids.² The regenerative properties of the sea cucumber also are important in future biomedical developments.

Toxic Properties

Although sea cucumbers have proven to have many beneficial properties, at least 30 species also produce potent toxins that pose a danger to both humans and other wildlife.³ The toxins are collectively referred to as holothurin; however, specific species actually produce a variety of holothurin toxins with unique chemical structures. Each toxin is a variation of a specific triterpene glycoside called saponins, which are common glycosides in the plant world. Holothurin was the first saponin to be found in animals. The only animals known to contain holothurin are the echinoderms, including sea cucumbers and sea stars.¹ Holothurins A and B are the 2 groups of holothurin toxins produced specifically by sea cucumbers. The toxins are composed of roughly 60% glycosides and pigment; 30% free amino acids (alanine, arginine, cysteine, glycine, glutamic acid, histidine, serine, and valine); 5% to 10% insoluble proteins; and 1% cholesterol, salts, and polypeptides.³

Holothurins are concentrated in granules within specialized structures of the sea cucumber called Cuvierian tubules, which freely float in the posterior coelomic cavity of the sea cucumber and are attached at the base of the respiratory tree. It is with these tubules that sea cucumbers utilize a unique defensive mechanism. Upon disturbance, the sea cucumber will turn its posterior end to the threat and squeeze its body in a series of violent contractions, inducing a tear in the cloacal wall.⁴ The tubules pass through this tear, are autotomized from the attachment point at the respiratory tree, and are finally expelled through the anus onto the predator and into the surrounding waters. The tubules are both sticky on contact and poisonous due to the holothurin, allowing the sea cucumber to crawl away from the threat unscathed. Over time, the tubules will regenerate, allowing the sea cucumber to protect itself again in the face of future danger.

Aside from direct disturbance by a threat, sea cucumbers also are known to undergo evisceration due to high temperatures and oxygen deficiency.³ Species that lack Cuvierian tubules can still produce holothurin toxins, though the toxins are secreted onto the outer surface of the body wall and mainly pose a risk with direct contact undiluted by seawater.⁵ The toxin induces a neural blockade in other sea creatures through its interaction with ion channels. On Asian islands, sea cucumbers have been exploited for this ability and commonly are thrown into tidal pools by fishermen to paralyze fish for easier capture.¹

Effects on Human Skin

In humans, the holothurin toxins of sea cucumbers cause an acute irritant dermatitis upon contact with the skin.⁶ Fishermen or divers handling sea cucumbers without gloves may present with an irritant contact dermatitis characterized by marked erythema and swelling (Figure 2).^6-8 Additionally, holothurin toxins can cause irritation of the mucous membranes of the eyes and mouth. Contact with the mucous membranes of the eyes can induce a painful conjunctivitis that may result in blindness.^6,8 Ingestion of large quantities of sea cucumber can produce an anticoagulant effect, and toxins in some species act similar to cardiac glycosides.^3,9

In addition to their own toxins, sea cucumbers also can secrete undigested nematocysts of previously consumed cnidarians through the integument.^7,10 In this case, the result of direct contact with the body wall is similar to a jellyfish sting in addition to the irritant contact dermatitis caused by the holothurin toxin.

Treatment and Prevention

Irritant dermatitis resulting from contact with a holothurin toxin is first treated with cleansing of the affected area at the time of exposure with generous amounts of seawater or preferably hot seawater and soap. Most marine toxins are inactivated by heat, but holothurin is partially heat stable. Vinegar or isopropyl alcohol also have been used.⁹ The result is removal of the slime containing the holothurin toxin rather than deactivation of the toxin. Although this alone may relieve symptoms, dermatitis also may be addressed with topical anesthetics, corticosteroids, or, if a severe reaction has occurred, systemic steroids.⁹

Conjunctivitis should be addressed with copious irrigation with tap water and topical anesthesia. Following proper irrigation, providers may choose to follow up with fluorescein staining to rule out corneal injury.¹⁰

The dermatologic effects of holothurin toxins can be prevented with the use of gloves and diving masks or goggles. Proper protective wear should be utilized not only when directly handling sea cucumbers but also when swimming in water where sea cucumbers may be present. Systemic toxicity can be prevented by proper cooking, as holothurin toxins are only partially heat resistant and also are hydrolyzed into nontoxic products by gastric acid. Additionally, the species of the sea cucumber should be confirmed prior to consumption, as edible species are known to contain less toxin.¹

Conclusion

Although sea cucumbers have ecologic, culinary, and pharmaceutical value, they also can pose a threat to both humans and wildlife. The holothurin toxins produced by sea cucumbers cause a painful contact dermatitis and can lead to conjunctivitis and even blindness following eye exposure. Although the toxin is broken down into nontoxic metabolites by gastric acid, large amounts of potent variants can induce systemic effects. Individuals who come in contact with sea cucumbers, such as fishermen and divers, should utilize proper protection including gloves and protective eyewear.

Sea cucumbers—commonly known as trepang in Indonesia, namako in Japan, and hai shen in China, where they are treasured as a food delicacy—are sea creatures belonging to the phylum Echinodermata, class Holothuridea, and family Cucumariidae . ^1,2 They are an integral part of a variety of marine habitats, serving as cleaners as they filter through sediment for nutrients. They can be found on the ocean floor under hundreds of feet of water or in shallow sandy waters along the coast, but they most commonly are found living among coral reefs. Sea cucumbers look just as they sound—shaped like cucumbers or sausages, ranging from under 1 inch to upwards of 6 feet in length depending on the specific species (Figure 1). They have a group of tentacles around the mouth used for filtering sediment, and they move about the ocean floor on tubular feet protruding through the body wall, similar to a sea star.

Beneficial Properties and Cultural Relevance

Although more than 1200 species of sea cucumbers have been identified thus far, only about 20 of these are edible.² The most common of the edible species is Stichopus japonicus, which can be found off the coasts of Korea, China, Japan, and Russia. This particular species most commonly is used in traditional dishes and is divided into 3 groups based on the color: red, green, or black. The price and taste of sea cucumbers varies based on the color, with red being the most expensive.² The body wall of the sea cucumber is cleaned, repeatedly boiled, and dried until edible. It is considered a delicacy, not only in food but also in pharmaceutical forms, as it is comprised of a variety of vitamins, minerals, and other nutrients that are thought to provide anticancer, anticoagulant, antioxidant, antifungal, and anti-inflammatory properties. Components of the body wall include collagen, mucopolysaccharides, peptides, gelatin, glycosaminoglycans, glycosides (including various holotoxins), hydroxylates, saponins, and fatty acids.² The regenerative properties of the sea cucumber also are important in future biomedical developments.

Toxic Properties

Although sea cucumbers have proven to have many beneficial properties, at least 30 species also produce potent toxins that pose a danger to both humans and other wildlife.³ The toxins are collectively referred to as holothurin; however, specific species actually produce a variety of holothurin toxins with unique chemical structures. Each toxin is a variation of a specific triterpene glycoside called saponins, which are common glycosides in the plant world. Holothurin was the first saponin to be found in animals. The only animals known to contain holothurin are the echinoderms, including sea cucumbers and sea stars.¹ Holothurins A and B are the 2 groups of holothurin toxins produced specifically by sea cucumbers. The toxins are composed of roughly 60% glycosides and pigment; 30% free amino acids (alanine, arginine, cysteine, glycine, glutamic acid, histidine, serine, and valine); 5% to 10% insoluble proteins; and 1% cholesterol, salts, and polypeptides.³

Holothurins are concentrated in granules within specialized structures of the sea cucumber called Cuvierian tubules, which freely float in the posterior coelomic cavity of the sea cucumber and are attached at the base of the respiratory tree. It is with these tubules that sea cucumbers utilize a unique defensive mechanism. Upon disturbance, the sea cucumber will turn its posterior end to the threat and squeeze its body in a series of violent contractions, inducing a tear in the cloacal wall.⁴ The tubules pass through this tear, are autotomized from the attachment point at the respiratory tree, and are finally expelled through the anus onto the predator and into the surrounding waters. The tubules are both sticky on contact and poisonous due to the holothurin, allowing the sea cucumber to crawl away from the threat unscathed. Over time, the tubules will regenerate, allowing the sea cucumber to protect itself again in the face of future danger.

Aside from direct disturbance by a threat, sea cucumbers also are known to undergo evisceration due to high temperatures and oxygen deficiency.³ Species that lack Cuvierian tubules can still produce holothurin toxins, though the toxins are secreted onto the outer surface of the body wall and mainly pose a risk with direct contact undiluted by seawater.⁵ The toxin induces a neural blockade in other sea creatures through its interaction with ion channels. On Asian islands, sea cucumbers have been exploited for this ability and commonly are thrown into tidal pools by fishermen to paralyze fish for easier capture.¹

Effects on Human Skin

In humans, the holothurin toxins of sea cucumbers cause an acute irritant dermatitis upon contact with the skin.⁶ Fishermen or divers handling sea cucumbers without gloves may present with an irritant contact dermatitis characterized by marked erythema and swelling (Figure 2).^6-8 Additionally, holothurin toxins can cause irritation of the mucous membranes of the eyes and mouth. Contact with the mucous membranes of the eyes can induce a painful conjunctivitis that may result in blindness.^6,8 Ingestion of large quantities of sea cucumber can produce an anticoagulant effect, and toxins in some species act similar to cardiac glycosides.^3,9

In addition to their own toxins, sea cucumbers also can secrete undigested nematocysts of previously consumed cnidarians through the integument.^7,10 In this case, the result of direct contact with the body wall is similar to a jellyfish sting in addition to the irritant contact dermatitis caused by the holothurin toxin.

Treatment and Prevention

Irritant dermatitis resulting from contact with a holothurin toxin is first treated with cleansing of the affected area at the time of exposure with generous amounts of seawater or preferably hot seawater and soap. Most marine toxins are inactivated by heat, but holothurin is partially heat stable. Vinegar or isopropyl alcohol also have been used.⁹ The result is removal of the slime containing the holothurin toxin rather than deactivation of the toxin. Although this alone may relieve symptoms, dermatitis also may be addressed with topical anesthetics, corticosteroids, or, if a severe reaction has occurred, systemic steroids.⁹

Conjunctivitis should be addressed with copious irrigation with tap water and topical anesthesia. Following proper irrigation, providers may choose to follow up with fluorescein staining to rule out corneal injury.¹⁰

The dermatologic effects of holothurin toxins can be prevented with the use of gloves and diving masks or goggles. Proper protective wear should be utilized not only when directly handling sea cucumbers but also when swimming in water where sea cucumbers may be present. Systemic toxicity can be prevented by proper cooking, as holothurin toxins are only partially heat resistant and also are hydrolyzed into nontoxic products by gastric acid. Additionally, the species of the sea cucumber should be confirmed prior to consumption, as edible species are known to contain less toxin.¹

Conclusion

Although sea cucumbers have ecologic, culinary, and pharmaceutical value, they also can pose a threat to both humans and wildlife. The holothurin toxins produced by sea cucumbers cause a painful contact dermatitis and can lead to conjunctivitis and even blindness following eye exposure. Although the toxin is broken down into nontoxic metabolites by gastric acid, large amounts of potent variants can induce systemic effects. Individuals who come in contact with sea cucumbers, such as fishermen and divers, should utilize proper protection including gloves and protective eyewear.

Sea cucumbers—commonly known as trepang in Indonesia, namako in Japan, and hai shen in China, where they are treasured as a food delicacy—are sea creatures belonging to the phylum Echinodermata, class Holothuridea, and family Cucumariidae . ^1,2 They are an integral part of a variety of marine habitats, serving as cleaners as they filter through sediment for nutrients. They can be found on the ocean floor under hundreds of feet of water or in shallow sandy waters along the coast, but they most commonly are found living among coral reefs. Sea cucumbers look just as they sound—shaped like cucumbers or sausages, ranging from under 1 inch to upwards of 6 feet in length depending on the specific species (Figure 1). They have a group of tentacles around the mouth used for filtering sediment, and they move about the ocean floor on tubular feet protruding through the body wall, similar to a sea star.

Beneficial Properties and Cultural Relevance

Although more than 1200 species of sea cucumbers have been identified thus far, only about 20 of these are edible.² The most common of the edible species is Stichopus japonicus, which can be found off the coasts of Korea, China, Japan, and Russia. This particular species most commonly is used in traditional dishes and is divided into 3 groups based on the color: red, green, or black. The price and taste of sea cucumbers varies based on the color, with red being the most expensive.² The body wall of the sea cucumber is cleaned, repeatedly boiled, and dried until edible. It is considered a delicacy, not only in food but also in pharmaceutical forms, as it is comprised of a variety of vitamins, minerals, and other nutrients that are thought to provide anticancer, anticoagulant, antioxidant, antifungal, and anti-inflammatory properties. Components of the body wall include collagen, mucopolysaccharides, peptides, gelatin, glycosaminoglycans, glycosides (including various holotoxins), hydroxylates, saponins, and fatty acids.² The regenerative properties of the sea cucumber also are important in future biomedical developments.

Toxic Properties

Although sea cucumbers have proven to have many beneficial properties, at least 30 species also produce potent toxins that pose a danger to both humans and other wildlife.³ The toxins are collectively referred to as holothurin; however, specific species actually produce a variety of holothurin toxins with unique chemical structures. Each toxin is a variation of a specific triterpene glycoside called saponins, which are common glycosides in the plant world. Holothurin was the first saponin to be found in animals. The only animals known to contain holothurin are the echinoderms, including sea cucumbers and sea stars.¹ Holothurins A and B are the 2 groups of holothurin toxins produced specifically by sea cucumbers. The toxins are composed of roughly 60% glycosides and pigment; 30% free amino acids (alanine, arginine, cysteine, glycine, glutamic acid, histidine, serine, and valine); 5% to 10% insoluble proteins; and 1% cholesterol, salts, and polypeptides.³

Holothurins are concentrated in granules within specialized structures of the sea cucumber called Cuvierian tubules, which freely float in the posterior coelomic cavity of the sea cucumber and are attached at the base of the respiratory tree. It is with these tubules that sea cucumbers utilize a unique defensive mechanism. Upon disturbance, the sea cucumber will turn its posterior end to the threat and squeeze its body in a series of violent contractions, inducing a tear in the cloacal wall.⁴ The tubules pass through this tear, are autotomized from the attachment point at the respiratory tree, and are finally expelled through the anus onto the predator and into the surrounding waters. The tubules are both sticky on contact and poisonous due to the holothurin, allowing the sea cucumber to crawl away from the threat unscathed. Over time, the tubules will regenerate, allowing the sea cucumber to protect itself again in the face of future danger.

Aside from direct disturbance by a threat, sea cucumbers also are known to undergo evisceration due to high temperatures and oxygen deficiency.³ Species that lack Cuvierian tubules can still produce holothurin toxins, though the toxins are secreted onto the outer surface of the body wall and mainly pose a risk with direct contact undiluted by seawater.⁵ The toxin induces a neural blockade in other sea creatures through its interaction with ion channels. On Asian islands, sea cucumbers have been exploited for this ability and commonly are thrown into tidal pools by fishermen to paralyze fish for easier capture.¹

Effects on Human Skin

In humans, the holothurin toxins of sea cucumbers cause an acute irritant dermatitis upon contact with the skin.⁶ Fishermen or divers handling sea cucumbers without gloves may present with an irritant contact dermatitis characterized by marked erythema and swelling (Figure 2).^6-8 Additionally, holothurin toxins can cause irritation of the mucous membranes of the eyes and mouth. Contact with the mucous membranes of the eyes can induce a painful conjunctivitis that may result in blindness.^6,8 Ingestion of large quantities of sea cucumber can produce an anticoagulant effect, and toxins in some species act similar to cardiac glycosides.^3,9

In addition to their own toxins, sea cucumbers also can secrete undigested nematocysts of previously consumed cnidarians through the integument.^7,10 In this case, the result of direct contact with the body wall is similar to a jellyfish sting in addition to the irritant contact dermatitis caused by the holothurin toxin.

Treatment and Prevention

Irritant dermatitis resulting from contact with a holothurin toxin is first treated with cleansing of the affected area at the time of exposure with generous amounts of seawater or preferably hot seawater and soap. Most marine toxins are inactivated by heat, but holothurin is partially heat stable. Vinegar or isopropyl alcohol also have been used.⁹ The result is removal of the slime containing the holothurin toxin rather than deactivation of the toxin. Although this alone may relieve symptoms, dermatitis also may be addressed with topical anesthetics, corticosteroids, or, if a severe reaction has occurred, systemic steroids.⁹

Conjunctivitis should be addressed with copious irrigation with tap water and topical anesthesia. Following proper irrigation, providers may choose to follow up with fluorescein staining to rule out corneal injury.¹⁰

The dermatologic effects of holothurin toxins can be prevented with the use of gloves and diving masks or goggles. Proper protective wear should be utilized not only when directly handling sea cucumbers but also when swimming in water where sea cucumbers may be present. Systemic toxicity can be prevented by proper cooking, as holothurin toxins are only partially heat resistant and also are hydrolyzed into nontoxic products by gastric acid. Additionally, the species of the sea cucumber should be confirmed prior to consumption, as edible species are known to contain less toxin.¹

Conclusion

Although sea cucumbers have ecologic, culinary, and pharmaceutical value, they also can pose a threat to both humans and wildlife. The holothurin toxins produced by sea cucumbers cause a painful contact dermatitis and can lead to conjunctivitis and even blindness following eye exposure. Although the toxin is broken down into nontoxic metabolites by gastric acid, large amounts of potent variants can induce systemic effects. Individuals who come in contact with sea cucumbers, such as fishermen and divers, should utilize proper protection including gloves and protective eyewear.

Irritable bowel syndrome (IBS) is one of the most common disorders managed by primary care physicians and gastroenterologists.¹ Characterized by abdominal pain coinciding with altered stool form and/or frequency as defined by the Rome IV diagnostic criteria,² symptoms range from mild to debilitating and may remarkably impair quality of life and work productivity.¹

The cause of IBS is poorly understood. Proposed pathophysiologic factors include impaired mucosal function, microbial imbalance, visceral hypersensitivity, psychologic dysfunction, genetic factors, neurotransmitter imbalance, postinfectious gastroenteritis, inflammation, and food intolerance, any or all of which may lead to the development and maintenance of IBS symptoms.³ More recent observations of inflammation in the intestinal lining^4,5 and proinflammatory peripherally circulating cytokines⁶ challenge its traditional classification as a functional disorder.

The cause of this inflammation is of intense interest, with speculation that the bacterial microbiota, bile acids, association with postinfectious gastroenteritis and inflammatory bowel disease cases, and/or foods may contribute. Although approximately 50% of individuals with IBS report that foods aggravate their symptoms,⁷ studies investigating type I antibody–mediated immediate hypersensitivity have largely failed to demonstrate a substantial link, prompting many authorities to regard these associations as food “intolerances” rather than true allergies. Based on this body of literature, a large 2010 consensus report on all aspects of food allergies advises against food allergy testing for IBS.⁸

In contrast, by utilizing type IV food allergen skin patch testing, 2 proof-of-concept studies^9,10 investigated a different allergic mechanism in IBS, namely cell-mediated delayed-type hypersensitivity. Because many foods and food additives are known to cause allergic contact dermatitis,¹¹ it was hypothesized that these foods may elicit a similar delayed-type hypersensitivity response in the intestinal lining in previously sensitized individuals. By following a patch test–guided food avoidance diet, a large subpopulation of patients with IBS experienced partial or complete IBS symptom relief.^9,10 Our study further investigates a role for food-related delayed-type hypersensitivities in the pathogenesis of IBS.

Methods

Patient Selection
This study was conducted in a secondary care community-based setting. All patients were self-referred over an 18-month period ending in October 2019, had physician-diagnosed IBS, and/or met the Rome IV criteria for IBS and presented expressly for the food patch testing on a fee-for-service basis. Subtype of IBS was determined on presentation by the self-reported historically predominant symptom. Duration of IBS symptoms was self-reported and was rounded to the nearest year for purposes of data collection.

Exclusion criteria included pregnancy, known allergy to adhesive tape or any of the food allergens used in the study, severe skin rash, symptoms that had a known cause other than IBS, or active treatment with systemic immunosuppressive medications.

Patch Testing
Skin patch testing was initiated using an extensive panel of 117 type IV food allergens (eTable)¹¹ identified in the literature,¹² most of which utilized standard compounded formulations¹³ or were available from reputable patch test manufacturers (Brial Allergen GmbH; Chemotechnique Diagnostics). This panel was not approved by the US Food and Drug Administration. The freeze-dried vegetable formulations were taken from the 2018 report.⁹ Standard skin patch test procedure protocols¹² were used, affixing the patches to the upper aspect of the back.

Following patch test application on day 1, two follow-up visits occurred on day 3 and either day 4 or day 5. On day 3, patches were removed, and the initial results were read by a board-certified dermatologist according to a standard grading system.¹⁴ Interpretation of patch tests included no reaction, questionable reaction consisting of macular erythema, weak reaction consisting of erythema and slight edema, or strong reaction consisting of erythema and marked edema. On day 4 or day 5, the final patch test reading was performed, and patients were informed of their results. Patients were advised to avoid ingestion of all foods that elicited a questionable or positive patch test response for at least 3 months, and information about the foods and their avoidance also was distributed and reviewed.

Food Avoidance Questionnaire
Patients with questionable or positive patch tests at 72 or 96 hours were advised of their eligibility to participate in an institutional review board–approved food avoidance questionnaire study investigating the utility of patch test–guided food avoidance on IBS symptoms. The questionnaire assessed the following: (1) baseline average abdominal pain prior to patch test–guided avoidance diet (0=no symptoms; 10=very severe); (2) average abdominal pain since initiation of patch test–guided avoidance diet (0=no symptoms; 10=very severe); (3) degree of improvement in overall IBS symptoms by the end of the food avoidance period (0=no improvement; 10=great improvement); (4) compliance with the avoidance diet for the duration of the avoidance period (completely, partially, not at all, or not sure).

Questionnaires and informed consent were mailed to patients via the US Postal Service 3 months after completing the patch testing. The questionnaire and consent were to be completed and returned after dietary avoidance of the identified allergens for at least 3 months. Patients were not compensated for participation in the study.

Statistical Analysis
Statistical analysis of data collected from study questionnaires was performed with Microsoft Excel. Mean abdominal pain and mean global improvement scores were reported along with 1 SD of the mean. For comparison of mean abdominal pain and improvement in global IBS symptoms from baseline to after 3 months of identified allergen avoidance, a Mann-Whitney U test was performed, with P<.05 being considered statistically significant.

Results

Thirty-seven consecutive patients underwent the testing and were eligible for the study. Nineteen patients were included in the study by virtue of completing and returning their posttest food avoidance questionnaire and informed consent. Eighteen patients were White and 1 was Asian. Subcategories of IBS were diarrhea predominant (9 [47.4%]), constipation predominant (3 [15.8%]), mixed type (5 [26.3%]), and undetermined type (2 [10.5%]). Questionnaire answers were reported after a mean (SD) duration of patch test–directed food avoidance of 4.5 (3.0) months (Table 1).

Overall Improvement
Fifteen (78.9%) patients reported at least slight to great improvement in their global IBS symptoms, and 4 (21.1%) reported no improvement (Table 2), with a mean (SD) improvement score of 5.1 (3.3)(P<.00001).

Comment

Despite intense research interest and a growing number of new medications for IBS approved by the US Food and Drug Administration, there remains a large void in the search for cost-effective and efficacious approaches for IBS evaluation and treatment. In addition to major disturbances in quality of life,^14,15 the cost to society in direct medical expenses and indirect costs associated with loss of productivity and work absenteeism is considerable; estimates range from $21 billion or more annually.¹⁶

Food Hypersensitivities Triggering IBS
This study further evaluated a role for skin patch testing to identify delayed-type (type IV) food hypersensitivities that trigger IBS symptoms and differed from the prior investigations^9,10 in that the symptoms used to define IBS were updated from the Rome III¹⁷ to the newer Rome IV² criteria. The data presented here show moderate to great improvement in global IBS symptoms in 58% (11/19) of patients, which is in line with a 2018 report of 40 study participants for whom follow-up at 3 or more months was available,⁹ providing additional support for a role for type IV food allergies in causing the same gastrointestinal tract symptoms that define IBS. The distinction between food-related studies, including this one, that implicate food allergies^9,10 and prior studies that did not support a role for food allergies in IBS pathogenesis⁸ can be accounted for by the type of allergy investigated. Conclusions that IBS flares after food ingestion were attributable to intolerance rather than true allergy were based on results investigating only the humoral arm and failed to consider the cell-mediated arm of the immune system. As such, foods that appear to trigger IBS symptoms on an allergic basis in our study are recognized in the literature¹² as type IV allergens that elicit cell-mediated immunologic responses rather than more widely recognized type I allergens, such as peanuts and shellfish, that elicit immediate-type hypersensitivity responses. Although any type IV food allergen(s) could be responsible, a pattern emerged in this study and the study published in 2018.⁹ Namely, some foods stood out as more frequently inducing patch test reactions, with the 3 most common being carmine, cinnamon bark oil, and sodium bisulfite (eTable). The sample size is relatively small, but the results raise the question of whether these foods are the most likely to trigger IBS symptoms in the general population. If so, is it the result of a higher innate sensitizing potential and/or a higher frequency of exposure in commonly eaten foods? Larger randomized clinical trials are needed.

Immune Response and IBS
There is mounting evidence that the immune system may play a role in the pathophysiology of IBS.¹⁸ Both lymphocyte infiltration of the myenteric plexus and an increase in intestinal mucosal T lymphocytes have been observed, and it is generally accepted that the mucosal immune system seems to be activated, at least in a subset of patients with IBS.¹⁹ Irritable bowel syndrome associations with quiescent inflammatory bowel disease or postinfectious gastroenteritis provide 2 potential causes for the inflammation, but most IBS patients have had neither.²⁰ The mucosal lining of the intestine and immune system have vast exposure to intraluminal allergens in transit, and it is hypothesized that the same delayed-type hypersensitivity response elicited in the skin by patch testing is elicited in the intestine, resulting in the inflammation that triggers IBS symptoms.¹⁰ The results here add to the growing body of evidence that ingestion of type IV food allergens by previously sensitized individuals could, in fact, be the primary source of the inflammation observed in a large subpopulation of individuals who carry a diagnosis of IBS.

Food Allergens in Patch Testing
Many of the food allergens used in this study are commonly found in various nonfood products that may contact the skin. For example, many flavorings are used as fragrances, and many preservatives, binders, thickeners, emulsifiers, and stabilizers serve the same role in moisturizers, cosmetics, and topical medications. Likewise, nickel sulfate hexahydrate, ubiquitous in foods that arise from the earth, often is found in metal in jewelry, clothing components, and cell phones. All are potential sensitizers. Thus, the question may arise whether the causal relationship between the food allergens identified by patch testing and IBS symptoms might be more of a systemic effect akin to systemic contact dermatitis as sometimes follows ingestion of an allergen to which an individual has been topically sensitized, rather than the proposed localized immunologic response in the intestinal lining. We were unaware of patient history of allergic contact dermatitis to any of the patch test allergens in this study, but the dermatologist author here (M.S.) has unpublished experience with 2 other patients with IBS who have benefited from low-nickel diets after having had positive patch tests to nickel sulfate hexahydrate and who, in retrospect, did report a history of earring dermatitis. Future investigations using pre– and post–food challenge histologic assessments of the intestinal mucosa in patients who benefit from patch test–guided food avoidance diets should help to better define the mechanism.

Because IBS has not been traditionally associated with structural or biochemical abnormalities detectable with current routine diagnostic tools, it has long been viewed as a functional disorder. The findings published more recently,^9,10 in addition to this study’s results, would negate this functional classification in the subset of patients with IBS symptoms who experience sustained relief of their symptoms by patch test–directed food avoidance. The underlying delayed-type hypersensitivity pathogenesis of the IBS-like symptoms in these individuals would mandate an organic classification, aptly named allergic contact enteritis.¹⁰

Follow-up Data
The mean (SD) follow-up duration for this study and the 2018 report⁹ was 4.5 (3.0) months and 7.6 (3.9) months, respectively. The placebo effect is a concern for disorders such as IBS in which primarily subjective outcome measures are available,²¹ and in a retrospective analysis of 25 randomized, placebo-controlled IBS clinical trials, Spiller²² concluded the optimum length of such trials to be more than 3 months, which these studies exceed. Although not blinded or placebo controlled, the length of follow-up in the 2018 report⁹ and here enhances the validity of the results.

Limitation
The retrospective manner in which the self-assessments were reported in this study introduces the potential for recall bias, a variable that could affect results. The presence and direction of bias by any given individual cannot be known, making it difficult to determine any effect it may have had. Further investigation should include daily assessments and refine the primary study end points to include both abdominal pain and the defecation considerations that define IBS.

Conclusion

Food patch testing has the potential to offer a safe, cost-effective approach to the evaluation and management of IBS symptoms. Randomized clinical trials are needed to further investigate the validity of the proof-of-concept results to date. For patients who benefit from a patch test–guided avoidance diet, invasive and costly endoscopic, radiologic, and laboratory testing and pharmacologic management could be averted. Symptomatic relief could be attained simply by avoiding the implicated foods, essentially doing more by doing less. 


Irritable bowel syndrome (IBS) is one of the most common disorders managed by primary care physicians and gastroenterologists.¹ Characterized by abdominal pain coinciding with altered stool form and/or frequency as defined by the Rome IV diagnostic criteria,² symptoms range from mild to debilitating and may remarkably impair quality of life and work productivity.¹

The cause of IBS is poorly understood. Proposed pathophysiologic factors include impaired mucosal function, microbial imbalance, visceral hypersensitivity, psychologic dysfunction, genetic factors, neurotransmitter imbalance, postinfectious gastroenteritis, inflammation, and food intolerance, any or all of which may lead to the development and maintenance of IBS symptoms.³ More recent observations of inflammation in the intestinal lining^4,5 and proinflammatory peripherally circulating cytokines⁶ challenge its traditional classification as a functional disorder.

The cause of this inflammation is of intense interest, with speculation that the bacterial microbiota, bile acids, association with postinfectious gastroenteritis and inflammatory bowel disease cases, and/or foods may contribute. Although approximately 50% of individuals with IBS report that foods aggravate their symptoms,⁷ studies investigating type I antibody–mediated immediate hypersensitivity have largely failed to demonstrate a substantial link, prompting many authorities to regard these associations as food “intolerances” rather than true allergies. Based on this body of literature, a large 2010 consensus report on all aspects of food allergies advises against food allergy testing for IBS.⁸

In contrast, by utilizing type IV food allergen skin patch testing, 2 proof-of-concept studies^9,10 investigated a different allergic mechanism in IBS, namely cell-mediated delayed-type hypersensitivity. Because many foods and food additives are known to cause allergic contact dermatitis,¹¹ it was hypothesized that these foods may elicit a similar delayed-type hypersensitivity response in the intestinal lining in previously sensitized individuals. By following a patch test–guided food avoidance diet, a large subpopulation of patients with IBS experienced partial or complete IBS symptom relief.^9,10 Our study further investigates a role for food-related delayed-type hypersensitivities in the pathogenesis of IBS.

Methods

Patient Selection
This study was conducted in a secondary care community-based setting. All patients were self-referred over an 18-month period ending in October 2019, had physician-diagnosed IBS, and/or met the Rome IV criteria for IBS and presented expressly for the food patch testing on a fee-for-service basis. Subtype of IBS was determined on presentation by the self-reported historically predominant symptom. Duration of IBS symptoms was self-reported and was rounded to the nearest year for purposes of data collection.

Exclusion criteria included pregnancy, known allergy to adhesive tape or any of the food allergens used in the study, severe skin rash, symptoms that had a known cause other than IBS, or active treatment with systemic immunosuppressive medications.

Patch Testing
Skin patch testing was initiated using an extensive panel of 117 type IV food allergens (eTable)¹¹ identified in the literature,¹² most of which utilized standard compounded formulations¹³ or were available from reputable patch test manufacturers (Brial Allergen GmbH; Chemotechnique Diagnostics). This panel was not approved by the US Food and Drug Administration. The freeze-dried vegetable formulations were taken from the 2018 report.⁹ Standard skin patch test procedure protocols¹² were used, affixing the patches to the upper aspect of the back.

Following patch test application on day 1, two follow-up visits occurred on day 3 and either day 4 or day 5. On day 3, patches were removed, and the initial results were read by a board-certified dermatologist according to a standard grading system.¹⁴ Interpretation of patch tests included no reaction, questionable reaction consisting of macular erythema, weak reaction consisting of erythema and slight edema, or strong reaction consisting of erythema and marked edema. On day 4 or day 5, the final patch test reading was performed, and patients were informed of their results. Patients were advised to avoid ingestion of all foods that elicited a questionable or positive patch test response for at least 3 months, and information about the foods and their avoidance also was distributed and reviewed.

Food Avoidance Questionnaire
Patients with questionable or positive patch tests at 72 or 96 hours were advised of their eligibility to participate in an institutional review board–approved food avoidance questionnaire study investigating the utility of patch test–guided food avoidance on IBS symptoms. The questionnaire assessed the following: (1) baseline average abdominal pain prior to patch test–guided avoidance diet (0=no symptoms; 10=very severe); (2) average abdominal pain since initiation of patch test–guided avoidance diet (0=no symptoms; 10=very severe); (3) degree of improvement in overall IBS symptoms by the end of the food avoidance period (0=no improvement; 10=great improvement); (4) compliance with the avoidance diet for the duration of the avoidance period (completely, partially, not at all, or not sure).

Questionnaires and informed consent were mailed to patients via the US Postal Service 3 months after completing the patch testing. The questionnaire and consent were to be completed and returned after dietary avoidance of the identified allergens for at least 3 months. Patients were not compensated for participation in the study.

Statistical Analysis
Statistical analysis of data collected from study questionnaires was performed with Microsoft Excel. Mean abdominal pain and mean global improvement scores were reported along with 1 SD of the mean. For comparison of mean abdominal pain and improvement in global IBS symptoms from baseline to after 3 months of identified allergen avoidance, a Mann-Whitney U test was performed, with P<.05 being considered statistically significant.

Results

Thirty-seven consecutive patients underwent the testing and were eligible for the study. Nineteen patients were included in the study by virtue of completing and returning their posttest food avoidance questionnaire and informed consent. Eighteen patients were White and 1 was Asian. Subcategories of IBS were diarrhea predominant (9 [47.4%]), constipation predominant (3 [15.8%]), mixed type (5 [26.3%]), and undetermined type (2 [10.5%]). Questionnaire answers were reported after a mean (SD) duration of patch test–directed food avoidance of 4.5 (3.0) months (Table 1).

Overall Improvement
Fifteen (78.9%) patients reported at least slight to great improvement in their global IBS symptoms, and 4 (21.1%) reported no improvement (Table 2), with a mean (SD) improvement score of 5.1 (3.3)(P<.00001).

Comment

Despite intense research interest and a growing number of new medications for IBS approved by the US Food and Drug Administration, there remains a large void in the search for cost-effective and efficacious approaches for IBS evaluation and treatment. In addition to major disturbances in quality of life,^14,15 the cost to society in direct medical expenses and indirect costs associated with loss of productivity and work absenteeism is considerable; estimates range from $21 billion or more annually.¹⁶

Food Hypersensitivities Triggering IBS
This study further evaluated a role for skin patch testing to identify delayed-type (type IV) food hypersensitivities that trigger IBS symptoms and differed from the prior investigations^9,10 in that the symptoms used to define IBS were updated from the Rome III¹⁷ to the newer Rome IV² criteria. The data presented here show moderate to great improvement in global IBS symptoms in 58% (11/19) of patients, which is in line with a 2018 report of 40 study participants for whom follow-up at 3 or more months was available,⁹ providing additional support for a role for type IV food allergies in causing the same gastrointestinal tract symptoms that define IBS. The distinction between food-related studies, including this one, that implicate food allergies^9,10 and prior studies that did not support a role for food allergies in IBS pathogenesis⁸ can be accounted for by the type of allergy investigated. Conclusions that IBS flares after food ingestion were attributable to intolerance rather than true allergy were based on results investigating only the humoral arm and failed to consider the cell-mediated arm of the immune system. As such, foods that appear to trigger IBS symptoms on an allergic basis in our study are recognized in the literature¹² as type IV allergens that elicit cell-mediated immunologic responses rather than more widely recognized type I allergens, such as peanuts and shellfish, that elicit immediate-type hypersensitivity responses. Although any type IV food allergen(s) could be responsible, a pattern emerged in this study and the study published in 2018.⁹ Namely, some foods stood out as more frequently inducing patch test reactions, with the 3 most common being carmine, cinnamon bark oil, and sodium bisulfite (eTable). The sample size is relatively small, but the results raise the question of whether these foods are the most likely to trigger IBS symptoms in the general population. If so, is it the result of a higher innate sensitizing potential and/or a higher frequency of exposure in commonly eaten foods? Larger randomized clinical trials are needed.

Immune Response and IBS
There is mounting evidence that the immune system may play a role in the pathophysiology of IBS.¹⁸ Both lymphocyte infiltration of the myenteric plexus and an increase in intestinal mucosal T lymphocytes have been observed, and it is generally accepted that the mucosal immune system seems to be activated, at least in a subset of patients with IBS.¹⁹ Irritable bowel syndrome associations with quiescent inflammatory bowel disease or postinfectious gastroenteritis provide 2 potential causes for the inflammation, but most IBS patients have had neither.²⁰ The mucosal lining of the intestine and immune system have vast exposure to intraluminal allergens in transit, and it is hypothesized that the same delayed-type hypersensitivity response elicited in the skin by patch testing is elicited in the intestine, resulting in the inflammation that triggers IBS symptoms.¹⁰ The results here add to the growing body of evidence that ingestion of type IV food allergens by previously sensitized individuals could, in fact, be the primary source of the inflammation observed in a large subpopulation of individuals who carry a diagnosis of IBS.

Food Allergens in Patch Testing
Many of the food allergens used in this study are commonly found in various nonfood products that may contact the skin. For example, many flavorings are used as fragrances, and many preservatives, binders, thickeners, emulsifiers, and stabilizers serve the same role in moisturizers, cosmetics, and topical medications. Likewise, nickel sulfate hexahydrate, ubiquitous in foods that arise from the earth, often is found in metal in jewelry, clothing components, and cell phones. All are potential sensitizers. Thus, the question may arise whether the causal relationship between the food allergens identified by patch testing and IBS symptoms might be more of a systemic effect akin to systemic contact dermatitis as sometimes follows ingestion of an allergen to which an individual has been topically sensitized, rather than the proposed localized immunologic response in the intestinal lining. We were unaware of patient history of allergic contact dermatitis to any of the patch test allergens in this study, but the dermatologist author here (M.S.) has unpublished experience with 2 other patients with IBS who have benefited from low-nickel diets after having had positive patch tests to nickel sulfate hexahydrate and who, in retrospect, did report a history of earring dermatitis. Future investigations using pre– and post–food challenge histologic assessments of the intestinal mucosa in patients who benefit from patch test–guided food avoidance diets should help to better define the mechanism.

Because IBS has not been traditionally associated with structural or biochemical abnormalities detectable with current routine diagnostic tools, it has long been viewed as a functional disorder. The findings published more recently,^9,10 in addition to this study’s results, would negate this functional classification in the subset of patients with IBS symptoms who experience sustained relief of their symptoms by patch test–directed food avoidance. The underlying delayed-type hypersensitivity pathogenesis of the IBS-like symptoms in these individuals would mandate an organic classification, aptly named allergic contact enteritis.¹⁰

Follow-up Data
The mean (SD) follow-up duration for this study and the 2018 report⁹ was 4.5 (3.0) months and 7.6 (3.9) months, respectively. The placebo effect is a concern for disorders such as IBS in which primarily subjective outcome measures are available,²¹ and in a retrospective analysis of 25 randomized, placebo-controlled IBS clinical trials, Spiller²² concluded the optimum length of such trials to be more than 3 months, which these studies exceed. Although not blinded or placebo controlled, the length of follow-up in the 2018 report⁹ and here enhances the validity of the results.

Limitation
The retrospective manner in which the self-assessments were reported in this study introduces the potential for recall bias, a variable that could affect results. The presence and direction of bias by any given individual cannot be known, making it difficult to determine any effect it may have had. Further investigation should include daily assessments and refine the primary study end points to include both abdominal pain and the defecation considerations that define IBS.

Conclusion

Food patch testing has the potential to offer a safe, cost-effective approach to the evaluation and management of IBS symptoms. Randomized clinical trials are needed to further investigate the validity of the proof-of-concept results to date. For patients who benefit from a patch test–guided avoidance diet, invasive and costly endoscopic, radiologic, and laboratory testing and pharmacologic management could be averted. Symptomatic relief could be attained simply by avoiding the implicated foods, essentially doing more by doing less. 


Irritable bowel syndrome (IBS) is one of the most common disorders managed by primary care physicians and gastroenterologists.¹ Characterized by abdominal pain coinciding with altered stool form and/or frequency as defined by the Rome IV diagnostic criteria,² symptoms range from mild to debilitating and may remarkably impair quality of life and work productivity.¹

The cause of IBS is poorly understood. Proposed pathophysiologic factors include impaired mucosal function, microbial imbalance, visceral hypersensitivity, psychologic dysfunction, genetic factors, neurotransmitter imbalance, postinfectious gastroenteritis, inflammation, and food intolerance, any or all of which may lead to the development and maintenance of IBS symptoms.³ More recent observations of inflammation in the intestinal lining^4,5 and proinflammatory peripherally circulating cytokines⁶ challenge its traditional classification as a functional disorder.

The cause of this inflammation is of intense interest, with speculation that the bacterial microbiota, bile acids, association with postinfectious gastroenteritis and inflammatory bowel disease cases, and/or foods may contribute. Although approximately 50% of individuals with IBS report that foods aggravate their symptoms,⁷ studies investigating type I antibody–mediated immediate hypersensitivity have largely failed to demonstrate a substantial link, prompting many authorities to regard these associations as food “intolerances” rather than true allergies. Based on this body of literature, a large 2010 consensus report on all aspects of food allergies advises against food allergy testing for IBS.⁸

In contrast, by utilizing type IV food allergen skin patch testing, 2 proof-of-concept studies^9,10 investigated a different allergic mechanism in IBS, namely cell-mediated delayed-type hypersensitivity. Because many foods and food additives are known to cause allergic contact dermatitis,¹¹ it was hypothesized that these foods may elicit a similar delayed-type hypersensitivity response in the intestinal lining in previously sensitized individuals. By following a patch test–guided food avoidance diet, a large subpopulation of patients with IBS experienced partial or complete IBS symptom relief.^9,10 Our study further investigates a role for food-related delayed-type hypersensitivities in the pathogenesis of IBS.

Methods

Patient Selection
This study was conducted in a secondary care community-based setting. All patients were self-referred over an 18-month period ending in October 2019, had physician-diagnosed IBS, and/or met the Rome IV criteria for IBS and presented expressly for the food patch testing on a fee-for-service basis. Subtype of IBS was determined on presentation by the self-reported historically predominant symptom. Duration of IBS symptoms was self-reported and was rounded to the nearest year for purposes of data collection.

Exclusion criteria included pregnancy, known allergy to adhesive tape or any of the food allergens used in the study, severe skin rash, symptoms that had a known cause other than IBS, or active treatment with systemic immunosuppressive medications.

Patch Testing
Skin patch testing was initiated using an extensive panel of 117 type IV food allergens (eTable)¹¹ identified in the literature,¹² most of which utilized standard compounded formulations¹³ or were available from reputable patch test manufacturers (Brial Allergen GmbH; Chemotechnique Diagnostics). This panel was not approved by the US Food and Drug Administration. The freeze-dried vegetable formulations were taken from the 2018 report.⁹ Standard skin patch test procedure protocols¹² were used, affixing the patches to the upper aspect of the back.

Following patch test application on day 1, two follow-up visits occurred on day 3 and either day 4 or day 5. On day 3, patches were removed, and the initial results were read by a board-certified dermatologist according to a standard grading system.¹⁴ Interpretation of patch tests included no reaction, questionable reaction consisting of macular erythema, weak reaction consisting of erythema and slight edema, or strong reaction consisting of erythema and marked edema. On day 4 or day 5, the final patch test reading was performed, and patients were informed of their results. Patients were advised to avoid ingestion of all foods that elicited a questionable or positive patch test response for at least 3 months, and information about the foods and their avoidance also was distributed and reviewed.

Food Avoidance Questionnaire
Patients with questionable or positive patch tests at 72 or 96 hours were advised of their eligibility to participate in an institutional review board–approved food avoidance questionnaire study investigating the utility of patch test–guided food avoidance on IBS symptoms. The questionnaire assessed the following: (1) baseline average abdominal pain prior to patch test–guided avoidance diet (0=no symptoms; 10=very severe); (2) average abdominal pain since initiation of patch test–guided avoidance diet (0=no symptoms; 10=very severe); (3) degree of improvement in overall IBS symptoms by the end of the food avoidance period (0=no improvement; 10=great improvement); (4) compliance with the avoidance diet for the duration of the avoidance period (completely, partially, not at all, or not sure).

Questionnaires and informed consent were mailed to patients via the US Postal Service 3 months after completing the patch testing. The questionnaire and consent were to be completed and returned after dietary avoidance of the identified allergens for at least 3 months. Patients were not compensated for participation in the study.

Statistical Analysis
Statistical analysis of data collected from study questionnaires was performed with Microsoft Excel. Mean abdominal pain and mean global improvement scores were reported along with 1 SD of the mean. For comparison of mean abdominal pain and improvement in global IBS symptoms from baseline to after 3 months of identified allergen avoidance, a Mann-Whitney U test was performed, with P<.05 being considered statistically significant.

Results

Thirty-seven consecutive patients underwent the testing and were eligible for the study. Nineteen patients were included in the study by virtue of completing and returning their posttest food avoidance questionnaire and informed consent. Eighteen patients were White and 1 was Asian. Subcategories of IBS were diarrhea predominant (9 [47.4%]), constipation predominant (3 [15.8%]), mixed type (5 [26.3%]), and undetermined type (2 [10.5%]). Questionnaire answers were reported after a mean (SD) duration of patch test–directed food avoidance of 4.5 (3.0) months (Table 1).

Overall Improvement
Fifteen (78.9%) patients reported at least slight to great improvement in their global IBS symptoms, and 4 (21.1%) reported no improvement (Table 2), with a mean (SD) improvement score of 5.1 (3.3)(P<.00001).

Comment

Despite intense research interest and a growing number of new medications for IBS approved by the US Food and Drug Administration, there remains a large void in the search for cost-effective and efficacious approaches for IBS evaluation and treatment. In addition to major disturbances in quality of life,^14,15 the cost to society in direct medical expenses and indirect costs associated with loss of productivity and work absenteeism is considerable; estimates range from $21 billion or more annually.¹⁶

Food Hypersensitivities Triggering IBS
This study further evaluated a role for skin patch testing to identify delayed-type (type IV) food hypersensitivities that trigger IBS symptoms and differed from the prior investigations^9,10 in that the symptoms used to define IBS were updated from the Rome III¹⁷ to the newer Rome IV² criteria. The data presented here show moderate to great improvement in global IBS symptoms in 58% (11/19) of patients, which is in line with a 2018 report of 40 study participants for whom follow-up at 3 or more months was available,⁹ providing additional support for a role for type IV food allergies in causing the same gastrointestinal tract symptoms that define IBS. The distinction between food-related studies, including this one, that implicate food allergies^9,10 and prior studies that did not support a role for food allergies in IBS pathogenesis⁸ can be accounted for by the type of allergy investigated. Conclusions that IBS flares after food ingestion were attributable to intolerance rather than true allergy were based on results investigating only the humoral arm and failed to consider the cell-mediated arm of the immune system. As such, foods that appear to trigger IBS symptoms on an allergic basis in our study are recognized in the literature¹² as type IV allergens that elicit cell-mediated immunologic responses rather than more widely recognized type I allergens, such as peanuts and shellfish, that elicit immediate-type hypersensitivity responses. Although any type IV food allergen(s) could be responsible, a pattern emerged in this study and the study published in 2018.⁹ Namely, some foods stood out as more frequently inducing patch test reactions, with the 3 most common being carmine, cinnamon bark oil, and sodium bisulfite (eTable). The sample size is relatively small, but the results raise the question of whether these foods are the most likely to trigger IBS symptoms in the general population. If so, is it the result of a higher innate sensitizing potential and/or a higher frequency of exposure in commonly eaten foods? Larger randomized clinical trials are needed.

Immune Response and IBS
There is mounting evidence that the immune system may play a role in the pathophysiology of IBS.¹⁸ Both lymphocyte infiltration of the myenteric plexus and an increase in intestinal mucosal T lymphocytes have been observed, and it is generally accepted that the mucosal immune system seems to be activated, at least in a subset of patients with IBS.¹⁹ Irritable bowel syndrome associations with quiescent inflammatory bowel disease or postinfectious gastroenteritis provide 2 potential causes for the inflammation, but most IBS patients have had neither.²⁰ The mucosal lining of the intestine and immune system have vast exposure to intraluminal allergens in transit, and it is hypothesized that the same delayed-type hypersensitivity response elicited in the skin by patch testing is elicited in the intestine, resulting in the inflammation that triggers IBS symptoms.¹⁰ The results here add to the growing body of evidence that ingestion of type IV food allergens by previously sensitized individuals could, in fact, be the primary source of the inflammation observed in a large subpopulation of individuals who carry a diagnosis of IBS.

Food Allergens in Patch Testing
Many of the food allergens used in this study are commonly found in various nonfood products that may contact the skin. For example, many flavorings are used as fragrances, and many preservatives, binders, thickeners, emulsifiers, and stabilizers serve the same role in moisturizers, cosmetics, and topical medications. Likewise, nickel sulfate hexahydrate, ubiquitous in foods that arise from the earth, often is found in metal in jewelry, clothing components, and cell phones. All are potential sensitizers. Thus, the question may arise whether the causal relationship between the food allergens identified by patch testing and IBS symptoms might be more of a systemic effect akin to systemic contact dermatitis as sometimes follows ingestion of an allergen to which an individual has been topically sensitized, rather than the proposed localized immunologic response in the intestinal lining. We were unaware of patient history of allergic contact dermatitis to any of the patch test allergens in this study, but the dermatologist author here (M.S.) has unpublished experience with 2 other patients with IBS who have benefited from low-nickel diets after having had positive patch tests to nickel sulfate hexahydrate and who, in retrospect, did report a history of earring dermatitis. Future investigations using pre– and post–food challenge histologic assessments of the intestinal mucosa in patients who benefit from patch test–guided food avoidance diets should help to better define the mechanism.

Because IBS has not been traditionally associated with structural or biochemical abnormalities detectable with current routine diagnostic tools, it has long been viewed as a functional disorder. The findings published more recently,^9,10 in addition to this study’s results, would negate this functional classification in the subset of patients with IBS symptoms who experience sustained relief of their symptoms by patch test–directed food avoidance. The underlying delayed-type hypersensitivity pathogenesis of the IBS-like symptoms in these individuals would mandate an organic classification, aptly named allergic contact enteritis.¹⁰

Follow-up Data
The mean (SD) follow-up duration for this study and the 2018 report⁹ was 4.5 (3.0) months and 7.6 (3.9) months, respectively. The placebo effect is a concern for disorders such as IBS in which primarily subjective outcome measures are available,²¹ and in a retrospective analysis of 25 randomized, placebo-controlled IBS clinical trials, Spiller²² concluded the optimum length of such trials to be more than 3 months, which these studies exceed. Although not blinded or placebo controlled, the length of follow-up in the 2018 report⁹ and here enhances the validity of the results.

Limitation
The retrospective manner in which the self-assessments were reported in this study introduces the potential for recall bias, a variable that could affect results. The presence and direction of bias by any given individual cannot be known, making it difficult to determine any effect it may have had. Further investigation should include daily assessments and refine the primary study end points to include both abdominal pain and the defecation considerations that define IBS.

Conclusion

Food patch testing has the potential to offer a safe, cost-effective approach to the evaluation and management of IBS symptoms. Randomized clinical trials are needed to further investigate the validity of the proof-of-concept results to date. For patients who benefit from a patch test–guided avoidance diet, invasive and costly endoscopic, radiologic, and laboratory testing and pharmacologic management could be averted. Symptomatic relief could be attained simply by avoiding the implicated foods, essentially doing more by doing less.