Cutis

Erythema ab igne (EAI)(also known as toasted skin syndrome) was first described in the British Journal of Dermatology in the 20th century, ¹ though it was known by physicians long before. Reticular netlike skin changes were seen in association with patients who spent extended time directly next to a heat source. This association led to the name of this condition, which literally means “redness by fire.” Indeed, EAI induced by chronic heat exposure has been described across the world for centuries. For example, in the cold regions of northern China, people used to sleep on beds of hot bricks called kang to stay warm at night. The people of India’s Kashmir district carried pots of hot coals called kangri next to the skin under large woven shawls to stay warm. In the past, Irish women often spent much time by a turf- or peat-burning fire. Chronic heat exposure in these cases can lead not only to EAI but also to aggressive types of cancer, often with a latency of 30 years or more. ²

More recently, the invention of home central heating led to a stark decrease in the number of cases associated with combustion-based heat, with a transition to etiologies such as use of hot water bottles, electric blankets, and electric space heaters. Over time, technological advances led to ever-increasing potential causes for EAI, such as laptops or cell phones, car heaters and heated seats, heated blankets,^3,4 infrared lamps for food, and even medical devices such as ultrasound-based heating products and convective temperature management systems for hospitalized patients. As technology evolves, so do the potential causes of EAI, requiring clinicians to diagnose and deduce the cause through a thorough social and medical history as well as a workup on the present illness with considerations for the anatomical location.^5-7 Herein, we describe the etiology of EAI, diagnosis, and treatment options.

Clinical Characteristics

Erythema ab igne begins as mild, transient, and erythematous macules and patches in a reticular pattern that resolve minutes to hours after removal of the heat source. With weeks to months of continued or repeated application of the heat source, the affected area eventually becomes hyperpigmented where there once was erythema (Figures 1 and 2). Sometimes papules, bullae, telangiectasia, and hyperkeratosis also form. The rash usually is asymptomatic, though pain, pruritus, and dysesthesia have been reported.⁷ Dermoscopy of EAI in the hyperpigmented stage can reveal diffuse superficial dark pigmentation, telangiectasia, and mild whitish scaling.⁸ Although the pathogenesis has remained elusive over the years, lesions do seem to be mostly associated with cumulative exposure to heat rather than length of exposure.⁷

Etiology of EAI

Anatomic Location—The affected site depends on the source of heat (Table). Classic examples of this condition include a patient with EAI presenting on the anterior thighs after working in front of a hot oven or a patient with chronic back pain presenting with lower-back EAI secondary to frequent use of a hot water bottle or heating pad.⁷ With evolving technology over the last few decades, new etiologies have become more common—teenagers are presenting with anterior thigh EAI secondary to frequent laptop use^2-29; patients are holding warm cell phones in their pant pockets, leading to unilateral geometric EAI on the anterior thigh (front pocket) or buttock (back pocket)³⁰; plug-in radiators under computer desks are causing EAI on the lower legs^31-34; and automobile seat heaters have been shown to cause EAI on the posterior legs.^5,35-37 Clinicians should consider anatomic location a critical clue for etiology.

Social History—There are rarer and more highly specific causes of EAI than simple heat exposure that can be parsed from a patient’s social history. Occupational exposure has been documented, such as bakers with exposure to ovens, foundry workers with exposure to heated metals, or fast-food workers with chronic exposure to infrared food lamps.^6,7 There also are cultural practices that can cause EAI. For example, the practice of cupping with moxibustion was shown to create a specific pattern in the shape of the cultural tool used.³⁸ When footbaths with Chinese herbal remedies are performed frequently with high heat, they can lead to EAI on the feet with a linear border at the ankles. There also have been reports of kotatsu (heated tables in Japan) leading to lower-body EAI.^39,40 These cultural practices also are more common in patients with darker skin types, which can lead to hyperpigmentation that is difficult to treat, making early diagnosis important.⁷

Medical History—Case reports have shown EAI caused by patients attempting to use heat-based methods for pain relief of an underlying serious disease such as cancer, bowel pathology (abdominal EAI), spinal disc prolapse (midline back EAI),⁴¹ sickle cell anemia, and renal pathology (posterior upper flank EAI).^6,7,40-49 Patients with hypothyroidism or anorexia have been noted to have generalized EAI sparing the face secondary to repeated and extended hot baths or showers.^50-53 One patient with schizophrenia was shown to have associated thermophilia due to a delusion that led the patient to soak in hot baths for long periods of time, leading to EAI.⁵⁴ Finally, all physicians should be aware of iatrogenic causes of EAI, such as use of warming devices, ultrasound-based warming techniques, and laser therapy for lipolysis. Inquire about the patient’s surgical history or intensive care unit stays as well as alternative medicine or chiropractic visits. Obtaining a history of medical procedures can be enlightening when an etiology is not immediately clear.^7,55,56

Diagnosis

Erythema ab igne is a clinical diagnosis based on recognizable cutaneous findings and a clear history of moderate heat exposure. However, when a clinical diagnosis of EAI is not certain (eg, when unable to obtain a clear history from the patient) or when malignant transformation is suspected, a biopsy can be performed. Pathologically, hematoxylin and eosin staining of EAI classically reveals dilated small vascular channels in the superficial dermis, hence a clinically reticular rash; interface dermatitis clinically manifesting as erythema; and pigment incontinence with melanin-laden macrophages consistent with clinical hyperpigmentation. Finally, for unclear reasons, increased numbers of elastic fibers classically are seen in biopsies of EAI.⁷

The differential diagnosis for a reticular patch includes livedo reticularis (Figure 3), which usually manifests as a more generalized rash in patients with chronic disease or coagulopathy such as systemic lupus erythematosus, cryoglobulinemia, or Raynaud phenomenon. When differentiating EAI from livedo reticularis or cutis marmorata, consider that both alternative diagnoses are more vascular appearing and are associated with cold exposure rather than heat exposure. In cases that are less reticular, livedo racemosa can be considered in the differential diagnosis. Finally, poikiloderma of Civatte can be reticular, particularly on dermoscopy, but the distribution on the neck with submental sparing should help to distinguish it from EAI unless a heat source around the neck is identified while taking the patient’s history.⁷

In babies, a reticular generalized rash is most likely to be cutis marmorata (Figure 4), which is a physiologic response to cold exposure that resolves with rewarming of the skin. A more serious condition—cutis marmorata telangiectatica congenita (Figure 5)—usually is present at birth, most frequently involves a single extremity, and notably does not resolve with rewarming. This is an important differential for EAI in children because it can be associated with vascular and neurologic anomalies as well as limb asymmetry. Finally, port-wine stains can sometimes be reticular in appearance and can mimic the early erythematous stages of EAI. However, unlike the erythematous stage of EAI, the port-wine stains will be present at birth.⁷

Emerging in 2020, an important differential diagnosis to consider is a cutaneous manifestation of COVID-19 infection. An erythematous, reticular, chilblainlike or transient livedo reticularis–like rash has been described as a cutaneous manifestation of COVID-19. Although the pathophysiology is still being elucidated, it is suspected that this is caused by a major vaso-occlusive crisis secondary to COVID-19–induced thrombotic vasculopathy. Interestingly, the majority of patients with this COVID-related exanthem also displayed symptoms of COVID-19 (eg, fever, cough) at the time of presentation,^57-60 but there also have been cases in patients who were asymptomatic or mildly symptomatic.⁶⁰

In some cases, EAI is an indication to screen for an underlying disease. For example, uncontrolled pain is an opportunity to improve interventions such as modifying the patient’s pain-control regimen, placing a palliative care pain consultation, or checking if the patient has had age-appropriate screenings for malignancy. New focal pain in a patient with a prior diagnosis of cancer may be a sign of a new metastasis. A thermophilic patient leaves opportunity to assess for underlying medical causes such as thyroid abnormalities or social/psychological issues. Geriatric patients who are diagnosed with EAI may need to be assessed for dementia or home safety issues. Patients with a history of diabetes mellitus can unknowingly develop EAI on the lower extremities, which may signal a need to assess the patient for peripheral neuropathy. Patients with gastroparesis secondary to diabetes also may develop EAI on the abdomen secondary to heating pad use for discomfort. These examples are a reminder to consider possible secondary comorbidities in all diagnoses of EAI.⁷ 

Prognosis

Although the prognosis of EAI is excellent if caught early, failure to diagnose this condition can lead to permanent discoloration of the skin and even malignancy.⁶ A rare sequela includes squamous cell carcinoma, most commonly seen in chronic cases of the lower leg, which is likely related to chronic inflammation of the skin.^61-65 Rare cases of poorly differentiated carcinoma,⁶⁶ cutaneous marginal zone lymphoma,⁶⁷ and Merkel cell carcinoma⁶⁸ have been reported. Patients diagnosed with EAI should receive normal periodic surveillance of the skin based on their medical history, though the physician should have an increased suspicion and plan for biopsy of any nodules or ulcerations found on the skin of the affected area.⁷

Treatments

Once the diagnosis of EAI is made, treatment starts with removal of the heat source causing the rash. Because the rash usually is asymptomatic, further treatment typically is not required. The discoloration can resolve over months or years, but permanent hyperpigmentation is not uncommon. If hyperpigmentation persists despite removal of the heat source and the patient desires further treatment for discoloration, there are few treatment options, none of which are approved by the US Food and Drug Administration for this condition.⁷ There is some evidence for the use of Nd:YAG lasers to reduce hyperpigmentation in EAI.⁶⁹ There have been some reports of treatment using topical hydroquinone and topical tretinoin in an attempt to lighten the skin. If associated hyperkeratosis or other epithelial atypia is present, the use of 5-fluorouracil may show some improvement.⁷⁰ One case report has been published of successful treatment with systemic mesoglycan and topical bioflavonoids.⁷¹ It also is conceivable that medications used to treat postinflammatory hyperpigmentation may be helpful in this condition (eg, kojic acid, arbutin, mild topical steroids, azelaic acid). Patients with darker skin may experience permanent discoloration and may not be good candidates for alternative treatments such as laser therapy due to the risk for inducible hyperpigmentation.⁷

Conclusion

No matter the etiology, EAI usually is a benign skin condition that is treated by removal of the causative heat source. Once a diagnosis is made, the clinician must work with the patient to determine the etiology. Care must be taken to ensure that there are no underlying signs, such as chronic pain or psychiatric illness, that could point to associated conditions. Rarely, sequalae such as cancers have been documented in areas of chronic EAI. Once the heat source is identified and removed, any remaining hyperpigmentation usually will self-resolve over months to years, though this may take longer in patients with darker skin types. If more aggressive treatment is preferred by the patient, laser therapy, topical medications, and oral over-the-counter vitamins have been tried with minimal responses. 

Erythema ab igne (EAI)(also known as toasted skin syndrome) was first described in the British Journal of Dermatology in the 20th century, ¹ though it was known by physicians long before. Reticular netlike skin changes were seen in association with patients who spent extended time directly next to a heat source. This association led to the name of this condition, which literally means “redness by fire.” Indeed, EAI induced by chronic heat exposure has been described across the world for centuries. For example, in the cold regions of northern China, people used to sleep on beds of hot bricks called kang to stay warm at night. The people of India’s Kashmir district carried pots of hot coals called kangri next to the skin under large woven shawls to stay warm. In the past, Irish women often spent much time by a turf- or peat-burning fire. Chronic heat exposure in these cases can lead not only to EAI but also to aggressive types of cancer, often with a latency of 30 years or more. ²

More recently, the invention of home central heating led to a stark decrease in the number of cases associated with combustion-based heat, with a transition to etiologies such as use of hot water bottles, electric blankets, and electric space heaters. Over time, technological advances led to ever-increasing potential causes for EAI, such as laptops or cell phones, car heaters and heated seats, heated blankets,^3,4 infrared lamps for food, and even medical devices such as ultrasound-based heating products and convective temperature management systems for hospitalized patients. As technology evolves, so do the potential causes of EAI, requiring clinicians to diagnose and deduce the cause through a thorough social and medical history as well as a workup on the present illness with considerations for the anatomical location.^5-7 Herein, we describe the etiology of EAI, diagnosis, and treatment options.

Clinical Characteristics

Erythema ab igne begins as mild, transient, and erythematous macules and patches in a reticular pattern that resolve minutes to hours after removal of the heat source. With weeks to months of continued or repeated application of the heat source, the affected area eventually becomes hyperpigmented where there once was erythema (Figures 1 and 2). Sometimes papules, bullae, telangiectasia, and hyperkeratosis also form. The rash usually is asymptomatic, though pain, pruritus, and dysesthesia have been reported.⁷ Dermoscopy of EAI in the hyperpigmented stage can reveal diffuse superficial dark pigmentation, telangiectasia, and mild whitish scaling.⁸ Although the pathogenesis has remained elusive over the years, lesions do seem to be mostly associated with cumulative exposure to heat rather than length of exposure.⁷

Etiology of EAI

Anatomic Location—The affected site depends on the source of heat (Table). Classic examples of this condition include a patient with EAI presenting on the anterior thighs after working in front of a hot oven or a patient with chronic back pain presenting with lower-back EAI secondary to frequent use of a hot water bottle or heating pad.⁷ With evolving technology over the last few decades, new etiologies have become more common—teenagers are presenting with anterior thigh EAI secondary to frequent laptop use^2-29; patients are holding warm cell phones in their pant pockets, leading to unilateral geometric EAI on the anterior thigh (front pocket) or buttock (back pocket)³⁰; plug-in radiators under computer desks are causing EAI on the lower legs^31-34; and automobile seat heaters have been shown to cause EAI on the posterior legs.^5,35-37 Clinicians should consider anatomic location a critical clue for etiology.

Social History—There are rarer and more highly specific causes of EAI than simple heat exposure that can be parsed from a patient’s social history. Occupational exposure has been documented, such as bakers with exposure to ovens, foundry workers with exposure to heated metals, or fast-food workers with chronic exposure to infrared food lamps.^6,7 There also are cultural practices that can cause EAI. For example, the practice of cupping with moxibustion was shown to create a specific pattern in the shape of the cultural tool used.³⁸ When footbaths with Chinese herbal remedies are performed frequently with high heat, they can lead to EAI on the feet with a linear border at the ankles. There also have been reports of kotatsu (heated tables in Japan) leading to lower-body EAI.^39,40 These cultural practices also are more common in patients with darker skin types, which can lead to hyperpigmentation that is difficult to treat, making early diagnosis important.⁷

Medical History—Case reports have shown EAI caused by patients attempting to use heat-based methods for pain relief of an underlying serious disease such as cancer, bowel pathology (abdominal EAI), spinal disc prolapse (midline back EAI),⁴¹ sickle cell anemia, and renal pathology (posterior upper flank EAI).^6,7,40-49 Patients with hypothyroidism or anorexia have been noted to have generalized EAI sparing the face secondary to repeated and extended hot baths or showers.^50-53 One patient with schizophrenia was shown to have associated thermophilia due to a delusion that led the patient to soak in hot baths for long periods of time, leading to EAI.⁵⁴ Finally, all physicians should be aware of iatrogenic causes of EAI, such as use of warming devices, ultrasound-based warming techniques, and laser therapy for lipolysis. Inquire about the patient’s surgical history or intensive care unit stays as well as alternative medicine or chiropractic visits. Obtaining a history of medical procedures can be enlightening when an etiology is not immediately clear.^7,55,56

Diagnosis

Erythema ab igne is a clinical diagnosis based on recognizable cutaneous findings and a clear history of moderate heat exposure. However, when a clinical diagnosis of EAI is not certain (eg, when unable to obtain a clear history from the patient) or when malignant transformation is suspected, a biopsy can be performed. Pathologically, hematoxylin and eosin staining of EAI classically reveals dilated small vascular channels in the superficial dermis, hence a clinically reticular rash; interface dermatitis clinically manifesting as erythema; and pigment incontinence with melanin-laden macrophages consistent with clinical hyperpigmentation. Finally, for unclear reasons, increased numbers of elastic fibers classically are seen in biopsies of EAI.⁷

The differential diagnosis for a reticular patch includes livedo reticularis (Figure 3), which usually manifests as a more generalized rash in patients with chronic disease or coagulopathy such as systemic lupus erythematosus, cryoglobulinemia, or Raynaud phenomenon. When differentiating EAI from livedo reticularis or cutis marmorata, consider that both alternative diagnoses are more vascular appearing and are associated with cold exposure rather than heat exposure. In cases that are less reticular, livedo racemosa can be considered in the differential diagnosis. Finally, poikiloderma of Civatte can be reticular, particularly on dermoscopy, but the distribution on the neck with submental sparing should help to distinguish it from EAI unless a heat source around the neck is identified while taking the patient’s history.⁷

In babies, a reticular generalized rash is most likely to be cutis marmorata (Figure 4), which is a physiologic response to cold exposure that resolves with rewarming of the skin. A more serious condition—cutis marmorata telangiectatica congenita (Figure 5)—usually is present at birth, most frequently involves a single extremity, and notably does not resolve with rewarming. This is an important differential for EAI in children because it can be associated with vascular and neurologic anomalies as well as limb asymmetry. Finally, port-wine stains can sometimes be reticular in appearance and can mimic the early erythematous stages of EAI. However, unlike the erythematous stage of EAI, the port-wine stains will be present at birth.⁷

Emerging in 2020, an important differential diagnosis to consider is a cutaneous manifestation of COVID-19 infection. An erythematous, reticular, chilblainlike or transient livedo reticularis–like rash has been described as a cutaneous manifestation of COVID-19. Although the pathophysiology is still being elucidated, it is suspected that this is caused by a major vaso-occlusive crisis secondary to COVID-19–induced thrombotic vasculopathy. Interestingly, the majority of patients with this COVID-related exanthem also displayed symptoms of COVID-19 (eg, fever, cough) at the time of presentation,^57-60 but there also have been cases in patients who were asymptomatic or mildly symptomatic.⁶⁰

In some cases, EAI is an indication to screen for an underlying disease. For example, uncontrolled pain is an opportunity to improve interventions such as modifying the patient’s pain-control regimen, placing a palliative care pain consultation, or checking if the patient has had age-appropriate screenings for malignancy. New focal pain in a patient with a prior diagnosis of cancer may be a sign of a new metastasis. A thermophilic patient leaves opportunity to assess for underlying medical causes such as thyroid abnormalities or social/psychological issues. Geriatric patients who are diagnosed with EAI may need to be assessed for dementia or home safety issues. Patients with a history of diabetes mellitus can unknowingly develop EAI on the lower extremities, which may signal a need to assess the patient for peripheral neuropathy. Patients with gastroparesis secondary to diabetes also may develop EAI on the abdomen secondary to heating pad use for discomfort. These examples are a reminder to consider possible secondary comorbidities in all diagnoses of EAI.⁷ 

Prognosis

Although the prognosis of EAI is excellent if caught early, failure to diagnose this condition can lead to permanent discoloration of the skin and even malignancy.⁶ A rare sequela includes squamous cell carcinoma, most commonly seen in chronic cases of the lower leg, which is likely related to chronic inflammation of the skin.^61-65 Rare cases of poorly differentiated carcinoma,⁶⁶ cutaneous marginal zone lymphoma,⁶⁷ and Merkel cell carcinoma⁶⁸ have been reported. Patients diagnosed with EAI should receive normal periodic surveillance of the skin based on their medical history, though the physician should have an increased suspicion and plan for biopsy of any nodules or ulcerations found on the skin of the affected area.⁷

Treatments

Once the diagnosis of EAI is made, treatment starts with removal of the heat source causing the rash. Because the rash usually is asymptomatic, further treatment typically is not required. The discoloration can resolve over months or years, but permanent hyperpigmentation is not uncommon. If hyperpigmentation persists despite removal of the heat source and the patient desires further treatment for discoloration, there are few treatment options, none of which are approved by the US Food and Drug Administration for this condition.⁷ There is some evidence for the use of Nd:YAG lasers to reduce hyperpigmentation in EAI.⁶⁹ There have been some reports of treatment using topical hydroquinone and topical tretinoin in an attempt to lighten the skin. If associated hyperkeratosis or other epithelial atypia is present, the use of 5-fluorouracil may show some improvement.⁷⁰ One case report has been published of successful treatment with systemic mesoglycan and topical bioflavonoids.⁷¹ It also is conceivable that medications used to treat postinflammatory hyperpigmentation may be helpful in this condition (eg, kojic acid, arbutin, mild topical steroids, azelaic acid). Patients with darker skin may experience permanent discoloration and may not be good candidates for alternative treatments such as laser therapy due to the risk for inducible hyperpigmentation.⁷

Conclusion

No matter the etiology, EAI usually is a benign skin condition that is treated by removal of the causative heat source. Once a diagnosis is made, the clinician must work with the patient to determine the etiology. Care must be taken to ensure that there are no underlying signs, such as chronic pain or psychiatric illness, that could point to associated conditions. Rarely, sequalae such as cancers have been documented in areas of chronic EAI. Once the heat source is identified and removed, any remaining hyperpigmentation usually will self-resolve over months to years, though this may take longer in patients with darker skin types. If more aggressive treatment is preferred by the patient, laser therapy, topical medications, and oral over-the-counter vitamins have been tried with minimal responses. 

Erythema ab igne (EAI)(also known as toasted skin syndrome) was first described in the British Journal of Dermatology in the 20th century, ¹ though it was known by physicians long before. Reticular netlike skin changes were seen in association with patients who spent extended time directly next to a heat source. This association led to the name of this condition, which literally means “redness by fire.” Indeed, EAI induced by chronic heat exposure has been described across the world for centuries. For example, in the cold regions of northern China, people used to sleep on beds of hot bricks called kang to stay warm at night. The people of India’s Kashmir district carried pots of hot coals called kangri next to the skin under large woven shawls to stay warm. In the past, Irish women often spent much time by a turf- or peat-burning fire. Chronic heat exposure in these cases can lead not only to EAI but also to aggressive types of cancer, often with a latency of 30 years or more. ²

More recently, the invention of home central heating led to a stark decrease in the number of cases associated with combustion-based heat, with a transition to etiologies such as use of hot water bottles, electric blankets, and electric space heaters. Over time, technological advances led to ever-increasing potential causes for EAI, such as laptops or cell phones, car heaters and heated seats, heated blankets,^3,4 infrared lamps for food, and even medical devices such as ultrasound-based heating products and convective temperature management systems for hospitalized patients. As technology evolves, so do the potential causes of EAI, requiring clinicians to diagnose and deduce the cause through a thorough social and medical history as well as a workup on the present illness with considerations for the anatomical location.^5-7 Herein, we describe the etiology of EAI, diagnosis, and treatment options.

Clinical Characteristics

Erythema ab igne begins as mild, transient, and erythematous macules and patches in a reticular pattern that resolve minutes to hours after removal of the heat source. With weeks to months of continued or repeated application of the heat source, the affected area eventually becomes hyperpigmented where there once was erythema (Figures 1 and 2). Sometimes papules, bullae, telangiectasia, and hyperkeratosis also form. The rash usually is asymptomatic, though pain, pruritus, and dysesthesia have been reported.⁷ Dermoscopy of EAI in the hyperpigmented stage can reveal diffuse superficial dark pigmentation, telangiectasia, and mild whitish scaling.⁸ Although the pathogenesis has remained elusive over the years, lesions do seem to be mostly associated with cumulative exposure to heat rather than length of exposure.⁷

Etiology of EAI

Anatomic Location—The affected site depends on the source of heat (Table). Classic examples of this condition include a patient with EAI presenting on the anterior thighs after working in front of a hot oven or a patient with chronic back pain presenting with lower-back EAI secondary to frequent use of a hot water bottle or heating pad.⁷ With evolving technology over the last few decades, new etiologies have become more common—teenagers are presenting with anterior thigh EAI secondary to frequent laptop use^2-29; patients are holding warm cell phones in their pant pockets, leading to unilateral geometric EAI on the anterior thigh (front pocket) or buttock (back pocket)³⁰; plug-in radiators under computer desks are causing EAI on the lower legs^31-34; and automobile seat heaters have been shown to cause EAI on the posterior legs.^5,35-37 Clinicians should consider anatomic location a critical clue for etiology.

Social History—There are rarer and more highly specific causes of EAI than simple heat exposure that can be parsed from a patient’s social history. Occupational exposure has been documented, such as bakers with exposure to ovens, foundry workers with exposure to heated metals, or fast-food workers with chronic exposure to infrared food lamps.^6,7 There also are cultural practices that can cause EAI. For example, the practice of cupping with moxibustion was shown to create a specific pattern in the shape of the cultural tool used.³⁸ When footbaths with Chinese herbal remedies are performed frequently with high heat, they can lead to EAI on the feet with a linear border at the ankles. There also have been reports of kotatsu (heated tables in Japan) leading to lower-body EAI.^39,40 These cultural practices also are more common in patients with darker skin types, which can lead to hyperpigmentation that is difficult to treat, making early diagnosis important.⁷

Medical History—Case reports have shown EAI caused by patients attempting to use heat-based methods for pain relief of an underlying serious disease such as cancer, bowel pathology (abdominal EAI), spinal disc prolapse (midline back EAI),⁴¹ sickle cell anemia, and renal pathology (posterior upper flank EAI).^6,7,40-49 Patients with hypothyroidism or anorexia have been noted to have generalized EAI sparing the face secondary to repeated and extended hot baths or showers.^50-53 One patient with schizophrenia was shown to have associated thermophilia due to a delusion that led the patient to soak in hot baths for long periods of time, leading to EAI.⁵⁴ Finally, all physicians should be aware of iatrogenic causes of EAI, such as use of warming devices, ultrasound-based warming techniques, and laser therapy for lipolysis. Inquire about the patient’s surgical history or intensive care unit stays as well as alternative medicine or chiropractic visits. Obtaining a history of medical procedures can be enlightening when an etiology is not immediately clear.^7,55,56

Diagnosis

Erythema ab igne is a clinical diagnosis based on recognizable cutaneous findings and a clear history of moderate heat exposure. However, when a clinical diagnosis of EAI is not certain (eg, when unable to obtain a clear history from the patient) or when malignant transformation is suspected, a biopsy can be performed. Pathologically, hematoxylin and eosin staining of EAI classically reveals dilated small vascular channels in the superficial dermis, hence a clinically reticular rash; interface dermatitis clinically manifesting as erythema; and pigment incontinence with melanin-laden macrophages consistent with clinical hyperpigmentation. Finally, for unclear reasons, increased numbers of elastic fibers classically are seen in biopsies of EAI.⁷

The differential diagnosis for a reticular patch includes livedo reticularis (Figure 3), which usually manifests as a more generalized rash in patients with chronic disease or coagulopathy such as systemic lupus erythematosus, cryoglobulinemia, or Raynaud phenomenon. When differentiating EAI from livedo reticularis or cutis marmorata, consider that both alternative diagnoses are more vascular appearing and are associated with cold exposure rather than heat exposure. In cases that are less reticular, livedo racemosa can be considered in the differential diagnosis. Finally, poikiloderma of Civatte can be reticular, particularly on dermoscopy, but the distribution on the neck with submental sparing should help to distinguish it from EAI unless a heat source around the neck is identified while taking the patient’s history.⁷

In babies, a reticular generalized rash is most likely to be cutis marmorata (Figure 4), which is a physiologic response to cold exposure that resolves with rewarming of the skin. A more serious condition—cutis marmorata telangiectatica congenita (Figure 5)—usually is present at birth, most frequently involves a single extremity, and notably does not resolve with rewarming. This is an important differential for EAI in children because it can be associated with vascular and neurologic anomalies as well as limb asymmetry. Finally, port-wine stains can sometimes be reticular in appearance and can mimic the early erythematous stages of EAI. However, unlike the erythematous stage of EAI, the port-wine stains will be present at birth.⁷

Emerging in 2020, an important differential diagnosis to consider is a cutaneous manifestation of COVID-19 infection. An erythematous, reticular, chilblainlike or transient livedo reticularis–like rash has been described as a cutaneous manifestation of COVID-19. Although the pathophysiology is still being elucidated, it is suspected that this is caused by a major vaso-occlusive crisis secondary to COVID-19–induced thrombotic vasculopathy. Interestingly, the majority of patients with this COVID-related exanthem also displayed symptoms of COVID-19 (eg, fever, cough) at the time of presentation,^57-60 but there also have been cases in patients who were asymptomatic or mildly symptomatic.⁶⁰

In some cases, EAI is an indication to screen for an underlying disease. For example, uncontrolled pain is an opportunity to improve interventions such as modifying the patient’s pain-control regimen, placing a palliative care pain consultation, or checking if the patient has had age-appropriate screenings for malignancy. New focal pain in a patient with a prior diagnosis of cancer may be a sign of a new metastasis. A thermophilic patient leaves opportunity to assess for underlying medical causes such as thyroid abnormalities or social/psychological issues. Geriatric patients who are diagnosed with EAI may need to be assessed for dementia or home safety issues. Patients with a history of diabetes mellitus can unknowingly develop EAI on the lower extremities, which may signal a need to assess the patient for peripheral neuropathy. Patients with gastroparesis secondary to diabetes also may develop EAI on the abdomen secondary to heating pad use for discomfort. These examples are a reminder to consider possible secondary comorbidities in all diagnoses of EAI.⁷ 

Prognosis

Although the prognosis of EAI is excellent if caught early, failure to diagnose this condition can lead to permanent discoloration of the skin and even malignancy.⁶ A rare sequela includes squamous cell carcinoma, most commonly seen in chronic cases of the lower leg, which is likely related to chronic inflammation of the skin.^61-65 Rare cases of poorly differentiated carcinoma,⁶⁶ cutaneous marginal zone lymphoma,⁶⁷ and Merkel cell carcinoma⁶⁸ have been reported. Patients diagnosed with EAI should receive normal periodic surveillance of the skin based on their medical history, though the physician should have an increased suspicion and plan for biopsy of any nodules or ulcerations found on the skin of the affected area.⁷

Treatments

Once the diagnosis of EAI is made, treatment starts with removal of the heat source causing the rash. Because the rash usually is asymptomatic, further treatment typically is not required. The discoloration can resolve over months or years, but permanent hyperpigmentation is not uncommon. If hyperpigmentation persists despite removal of the heat source and the patient desires further treatment for discoloration, there are few treatment options, none of which are approved by the US Food and Drug Administration for this condition.⁷ There is some evidence for the use of Nd:YAG lasers to reduce hyperpigmentation in EAI.⁶⁹ There have been some reports of treatment using topical hydroquinone and topical tretinoin in an attempt to lighten the skin. If associated hyperkeratosis or other epithelial atypia is present, the use of 5-fluorouracil may show some improvement.⁷⁰ One case report has been published of successful treatment with systemic mesoglycan and topical bioflavonoids.⁷¹ It also is conceivable that medications used to treat postinflammatory hyperpigmentation may be helpful in this condition (eg, kojic acid, arbutin, mild topical steroids, azelaic acid). Patients with darker skin may experience permanent discoloration and may not be good candidates for alternative treatments such as laser therapy due to the risk for inducible hyperpigmentation.⁷

Conclusion

No matter the etiology, EAI usually is a benign skin condition that is treated by removal of the causative heat source. Once a diagnosis is made, the clinician must work with the patient to determine the etiology. Care must be taken to ensure that there are no underlying signs, such as chronic pain or psychiatric illness, that could point to associated conditions. Rarely, sequalae such as cancers have been documented in areas of chronic EAI. Once the heat source is identified and removed, any remaining hyperpigmentation usually will self-resolve over months to years, though this may take longer in patients with darker skin types. If more aggressive treatment is preferred by the patient, laser therapy, topical medications, and oral over-the-counter vitamins have been tried with minimal responses. 

COVID-19 is a potentially severe systemic disease caused by SARS-CoV-2. SARS-CoV and Middle East respiratory syndrome (MERS-CoV) caused fatal epidemics in Asia in 2002 to 2003 and in the Arabian Peninsula in 2012, respectively. In 2019, SARS-CoV-2 was detected in patients with severe, sometimes fatal pneumonia of previously unknown origin; it rapidly spread around the world, and the World Health Organization declared the disease a pandemic on March 11, 2020. SARS-CoV-2 is a β-coronavirus that is genetically related to the bat coronavirus and SARS-CoV; it is a single-stranded RNA virus of which several variants and subvariants exist. The SARS-CoV-2 viral particles bind via their surface spike protein (S protein) to the angiotensin-converting enzyme 2 receptor present on the membrane of several cell types, including epidermal and adnexal keratinocytes.^1,2 The α and δ variants, predominant from 2020 to 2021, mainly affected the lower respiratory tract and caused severe, potentially fatal pneumonia, especially in patients older than 65 years and/or with comorbidities, such as obesity, hypertension, diabetes, and (iatrogenic) immunosuppression. The ο variant, which appeared in late 2021, is more contagious than the initial variants, but it causes a less severe disease preferentially affecting the upper respiratory airways.³ As of April 5, 2023, more than 762,000,000 confirmed cases of COVID-19 have been recorded worldwide, causing more than 6,800,000 deaths.⁴

Early studies from China describing the symptoms of COVID-19 reported a low frequency of skin manifestations (0.2%), probably because they were focused on the most severe disease symptoms.⁵ Subsequently, when COVID-19 spread to the rest of the world, an increasing number of skin manifestations were reported in association with the disease. After the first publication from northern Italy in spring 2020, which was specifically devoted to skin manifestations of COVID-19,⁶ an explosive number of publications reported a large number of skin manifestations, and national registries were established in several countries to record these manifestations, such as the American Academy of Dermatology and the International League of Dermatological Societies registry,^7,8 the COVIDSKIN registry of the French Dermatology Society,⁹ and the Italian registry.¹⁰ Highlighting the unprecedented number of scientific articles published on this new disease, a PubMed search of articles indexed for MEDLINE search using the terms SARS-CoV-2 or COVID-19, on April 6, 2023, revealed 351,596 articles; that is more than 300 articles published every day in this database alone, with a large number of them concerning the skin.

SKIN DISEASSES ASSOCIATED WITH COVID-19

There are several types of COVID-19–related skin manifestations, depending on the circumstances of onset and the evolution of the pandemic.

Skin Manifestations Associated With SARS-CoV-2 Infection

The estimated incidence varies greatly according to the published series of patients, possibly depending on the geographic location. The estimated incidence seems lower in Asian countries, such as China (0.2%)⁵ and Japan (0.56%),¹¹ compared with Europe (up to 20%).⁶ Skin manifestations associated with SARS-CoV-2 infection affect individuals of all ages, slightly more females, and are clinically polymorphous; some of them are associated with the severity of the infection.¹² They may precede, accompany, or appear after the symptoms of COVID-19, most often within a month of the infection, of which they rarely are the only manifestation; however, their precise relationship to SARS-CoV-2 is not always well known. They have been classified according to their clinical presentation into several forms.^13-15

Morbilliform Maculopapular Eruption—Representing 16% to 53% of skin manifestations, morbilliform and maculopapular eruptions usually appear within 15 days of infection; they manifest with more or less confluent erythematous macules that may be hemorrhagic/petechial, and usually are asymptomatic and rarely pruritic. The rash mainly affects the trunk and limbs, sparing the face, palmoplantar regions, and mucous membranes; it appears concomitantly with or a few days after the first symptoms of COVID-19 (eg, fever, respiratory symptoms), regresses within a few days, and does not appear to be associated with disease severity. The distinction from maculopapular drug eruptions may be subtle. Histologically, the rash manifests with a spongiform dermatitis (ie, variable parakeratosis; spongiosis; and a mixed dermal perivascular infiltrate of lymphocytes, eosinophils and histiocytes, depending on the lesion age)(Figure 1). The etiopathogenesis is unknown; it may involve immune complexes to SARS-CoV-2 deposited on skin vessels. Treatment is not mandatory; if necessary, local or systemic corticosteroids may be used.

Vesicular (Pseudovaricella) Rash—This rash accounts for 11% to 18% of all skin manifestations and usually appears within 15 days of COVID-19 onset. It manifests with small monomorphous or varicellalike (pseudopolymorphic) vesicles appearing on the trunk, usually in young patients. The vesicles may be herpetiform, hemorrhagic, or pruritic, and appear before or within 3 days of the onset of mild COVID-19 symptoms; they regress within a few days without scarring. Histologically, the lesions show basal cell vacuolization; multinucleated, dyskeratotic/apoptotic or ballooning/acantholytic epidermal keratinocytes; reticular degeneration of the epidermis; intraepidermal vesicles sometimes resembling herpetic vesicular infections or Grover disease; and mild dermal inflammation. There is no specific treatment.

Urticaria—Urticarial rash, or urticaria, represents 5% to 16% of skin manifestations; usually appears within 15 days of disease onset; and manifests with pruritic, migratory, edematous papules appearing mainly on the trunk and occasionally the face and limbs. The urticarial rash tends to be associated with more severe forms of the disease and regresses within a week, responding to antihistamines. Of note, clinically similar rashes can be caused by drugs. Histologically, the lesions show dermal edema and a mild perivascular lymphocytic infiltrate, sometimes admixed with eosinophils.

Chilblainlike Lesions—Chilblainlike lesions (CBLLs) account for 19% of skin manifestations associated with COVID-19¹³ and present as erythematous-purplish, edematous lesions that can be mildly pruritic or painful, appearing on the toes—COVID toes—and more rarely the fingers (Figure 2). They were seen epidemically during the first pandemic wave (2020 lockdown) in several countries, and clinically are very similar to, if not indistinguishable from, idiopathic chilblains, but are not necessarily associated with cold exposure. They appear in young, generally healthy patients or those with mild COVID-19 symptoms 2 to 4 weeks after symptom onset. They regress spontaneously or under local corticosteroid treatment within a few days or weeks. Histologically, CBLLs are indistinguishable from chilblains of other origins, namely idiopathic (seasonal) ones. They manifest with necrosis of epidermal keratinocytes; dermal edema that may be severe, leading to the development of subepidermal pseudobullae; a rather dense perivascular and perieccrine gland lymphocytic infiltrate; and sometimes with vascular lesions (eg, edema of endothelial cells, microthromboses of dermal capillaries and venules, fibrinoid deposits within the wall of dermal venules)(Figure 3).^16-18 Most patients (>80%) with CBLLs have negative serologic or polymerase chain reaction tests for SARS-CoV-2,¹⁹ which generated a lively debate about the role of SARS-CoV-2 in the genesis of CBLLs. According to some authors, SARS-CoV-2 plays no direct role, and CBLLs would occur in young people who sit or walk barefoot on cold floors at home during confinement.^20-23 Remarkably, CBLLs appeared in patients with no history of chilblains during a season that was not particularly cold, namely in France or in southern California, where their incidence was much higher compared to the same time period of prior years. Some reports have supported a direct role for the virus based on questionable observations of the virus within skin lesions (eg, sweat glands, endothelial cells) by immunohistochemistry, electron microscopy, and/or in situ hybridization.^17,24,25 A more satisfactory hypothesis would involve the role of a strong innate immunity leading to elimination of the virus before the development of specific antibodies via the increased production of type 1 interferon (IFN-1); this would affect the vessels, causing CBLLs. This mechanism would be similar to the one observed in some interferonopathies (eg, Aicardi-Goutières syndrome), also characterized by IFN-1 hypersecretion and chilblains.^26-29 According to this hypothesis, CBLLs should be considered a paraviral rash similar to other skin manifestations associated with COVID-19.³⁰

Acro-ischemia—Acro-ischemia livedoid lesions account for 1% to 6% of skin manifestations and comprise lesions of livedo (either reticulated or racemosa); necrotic acral bullae; and gangrenous necrosis of the extremities, especially the toes. The livedoid lesions most often appear within 15 days of COVID-19 symptom onset, and the purpuric lesions somewhat later (2–4 weeks); they mainly affect adult patients, last about 10 days, and are the hallmark of severe infection, presumably related to microthromboses of the cutaneous capillaries (endothelial dysfunction, prothrombotic state, elevated D-dimers). Histologically, they show capillary thrombosis and dermoepidermal necrosis (Figure 4).

Other Reported Polymorphic or Atypical Rashes—Erythema multiforme–like eruptions may appear before other COVID-19 symptoms and manifest as reddish-purple, nearly symmetric, diffuse, occasionally targetoid bullous or necrotic macules. The eruptions mainly affect adults and most often are seen on the palms, elbows, knees, and sometimes the mucous membranes. The rash regresses in 1 to 3 weeks without scarring and represents a delayed cutaneous hypersensitivity reaction. Histologically, the lesions show vacuolization of basal epidermal keratinocytes, keratinocyte necrosis, dermoepidermal detachment, a variably dense dermal T-lymphocytic infiltrate, and red blood cell extravasation (Figure 5).

Leukocytoclastic vasculitis may be generalized or localized. It manifests clinically by petechial/purpuric maculopapules, especially on the legs, mainly in elderly patients with COVID-19. Histologically, the lesions show necrotizing changes of dermal postcapillary venules, neutrophilic perivascular inflammation, red blood cell extravasation, and occasionally vascular IgA deposits by direct immunofluorescence examination. The course usually is benign.

The incidence of pityriasis rosea and of clinically similar rashes (referred to as “pityriasis rosea–like”) increased 5-fold during the COVID-19 pandemic.^31,32 These dermatoses manifest with erythematous, scaly, circinate plaques, typically with an initial herald lesion followed a few days later by smaller erythematous macules. Histologically, the lesions comprise a spongiform dermatitis with intraepidermal exocytosis of red blood cells and a mild to moderate dermal lymphocytic infiltrate.

Erythrodysesthesia, or hand-foot syndrome, manifests with edematous erythema and palmoplantar desquamation accompanied by a burning sensation or pain. This syndrome is known as an adverse effect of some chemotherapies because of the associated drug toxicity and sweat gland inflammation; it was observed in 40% of 666 COVID-19–positive patients with mild to moderate pneumonitis.³³

“COVID nose” is a rare cutaneous manifestation characterized by nasal pigmentation comprising multiple coalescent frecklelike macules on the tip and wings of the nose and sometimes the malar areas. These lesions predominantly appear in women aged 25 to 65 years and show on average 23 days after onset of COVID-19, which is usually mild. This pigmentation is similar to pigmentary changes after infection with chikungunya; it can be treated with depigmenting products such as azelaic acid and hydroquinone cream with sunscreen use, and it regresses in 2 to 4 months.³⁴

Telogen effluvium (excessive and temporary shedding of normal telogen club hairs of the entire scalp due to the disturbance of the hair cycle) is reportedly frequent in patients (48%) 1 month after COVID-19 infection, but it may appear later (after 12 weeks).³⁵ Alopecia also is frequently reported during long (or postacute) COVID-19 (ie, the symptomatic disease phase past the acute 4 weeks’ stage of the infection) and shows a female predominance³⁶; it likely represents the telogen effluvium seen 90 days after a severe illness. Trichodynia (pruritus, burning, pain, or paresthesia of the scalp) also is reportedly common (developing in more than 58% of patients) and is associated with telogen effluvium in 44% of cases. Several cases of alopecia areata (AA) triggered or aggravated by COVID-19 also have been reported^37,38; they could be explained by the “cytokine storm” triggered by the infection, involving T and B lymphocytes; plasmacytoid dendritic cells; natural killer cells with oversecretion of IL-6, IL-4, tumor necrosis factor α, and IFN type I; and a cytotoxic reaction associated with loss of the immune privilege of hair follicles.

Nail Manifestations

The red half-moon nail sign is an asymptomatic purplish-red band around the distal margin of the lunula that affects some adult patients with COVID-19.³⁹ It appears shortly after onset of symptoms, likely the manifestation of vascular inflammation in the nail bed, and regresses slowly after approximately 1 week.⁴⁰ Beau lines are transverse grooves in the nail plate due to the temporary arrest of the proximal nail matrix growth accompanying systemic illnesses; they appear approximately 2 to 3 weeks after the onset of COVID-19.⁴¹ Furthermore, nail alterations can be caused by drugs used to treat COVID-19, such as longitudinal melanonychia due to treatment with hydroxychloroquine or fluorescence of the lunula or nail plate due to treatment with favipiravir.⁴²

Multisystem Inflammatory Syndrome

Multisystem inflammatory syndrome (MIS) is clinically similar to Kawasaki disease; it typically affects children⁴³ and more rarely adults with COVID-19. It manifests with fever, weakness, and biological inflammation and also frequently with skin lesions (72%), which are polymorphous and include morbilliform rash (27%); urticaria (24%); periorbital edema (24%); nonspecific erythema (21.2%); retiform purpura (18%); targetoid lesions (15%); malar rash (15.2%); and periareolar erythema (6%).⁴⁴ Compared to Kawasaki disease, MIS affects slightly older children (mean age, 8.5 vs 3 years) and more frequently includes cardiac and gastrointestinal manifestations; the mortality rate also is slightly higher (2% vs 0.17%).⁴⁵

Confirmed COVID-19 Infection

At the beginning of the pandemic, skin manifestations were reported in patients who were suspected of having COVID-19 but did not always have biological confirmation of SARS-CoV-2 infection due to the unavailability of diagnostic tests or the physical impossibility of testing. However, subsequent studies have confirmed that most of these dermatoses were indeed associated with COVID-19 infection.^9,46 For example, a study of 655 patients with confirmed COVID-19 infection reported maculopapular (38%), vascular (22%), urticarial (15%), and vesicular (15%) rashes; erythema multiforme or Stevens-Johnson–like syndrome (3%, often related to the use of hydroxychloroquine); generalized pruritus (1%); and MIS (0.5%). The study confirmed that CBLLs were mostly seen in young patients with mild disease, whereas livedo (fixed rash) and retiform purpura occurred in older patients with a guarded prognosis.⁴⁶

Remarkably, most dermatoses associated with SARS-CoV-2 infection were reported during the initial waves of the pandemic, which were due to the α and δ viral variants. These manifestations were reported more rarely when the ο variant was predominant, even though most patients (63%) who developed CBLLs in the first wave also developed them during the second pandemic wave.⁴⁷ This decrease in the incidence of COVID-19–associated dermatoses could be because of the lower pathogenicity of the o variant,³ a lower tropism for the skin, and variations in SARS-CoV-2 antigenicity that would induce a different immunologic response, combined with an increasingly stronger herd immunity compared to the first pandemic waves achieved through vaccination and spontaneous infections in the population. Additional reasons may include different baseline characteristics in patients hospitalized with COVID-19 (regarding comorbidities, disease severity, and received treatments), and the possibility that some of the initially reported COVID-19–associated skin manifestations could have been produced by different etiologic agents.⁴⁸ In the last 2 years, COVID-19–related skin manifestations have been reported mainly as adverse events to COVID-19 vaccination.

CUTANEOUS ADVERSE EFFECTS OF DRUGS USED TO TREAT COVID-19

Prior to the advent of vaccines and specific treatments for SARS-CoV-2, various drugs were used—namely hydroxychloroquine, ivermectin, and tocilizumab—that did not prove efficacious and caused diverse adverse effects, including cutaneous eruptions such as urticaria, maculopapular eruptions, erythema multiforme or Stevens-Johnson syndrome, vasculitis, longitudinal melanonychia, and acute generalized exanthematous pustulosis.^49,50 Nirmatrelvir 150 mg–ritonavir 100 mg, which was authorized for emergency use by the US Food and Drug Administration for the treatment of COVID-19, is a viral protease inhibitor blocking the replication of the virus. Ritonavir can induce pruritus, maculopapular rash, acne, Stevens-Johnson syndrome, and toxic epidermal necrolysis; of note, these effects have been observed following administration of ritonavir for treatment of HIV at higher daily doses and for much longer periods of time compared with treatment of COVID-19 (600–1200 mg vs 200 mg/d, respectively). These cutaneous drug side effects are clinically similar to the manifestations caused either directly or indirectly by SARS-CoV-2 infection; therefore, it may be difficult to differentiate them.

DERMATOSES DUE TO PROTECTIVE DEVICES

Dermatoses due to personal protective equipment such as masks or face shields affected the general population and mostly health care professionals⁵¹; 54.4% of 879 health care professionals in one study reported such events.⁵² These dermatoses mainly include contact dermatitis of the face (nose, forehead, and cheeks) of irritant or allergic nature (eg, from preservatives releasing formaldehyde contained in masks and protective goggles). They manifest with skin dryness; desquamation; maceration; fissures; or erosions or ulcerations of the cheeks, forehead, and nose. Cases of pressure urticaria also have been reported. Irritant dermatitis induced by the frequent use of disinfectants (eg, soaps, hydroalcoholic sanitizing gels) also can affect the hands. Allergic hand dermatitis can be caused by medical gloves.

The term maskne (or mask acne) refers to a variety of mechanical acne due to the prolonged use of surgical masks (>4 hours per day for ≥6 weeks); it includes cases of de novo acne and cases of pre-existing acne aggravated by wearing a mask. Maskne is characterized by acne lesions located on the facial area covered by the mask (Figure 6). It is caused by follicular occlusion; increased sebum secretion; mechanical stress (pressure, friction); and dysbiosis of the microbiome induced by changes in heat, pH, and humidity. Preventive measures include application of noncomedogenic moisturizers or gauze before wearing the mask as well as facial cleansing with appropriate nonalcoholic products. Similar to acne, rosacea often is aggravated by prolonged wearing of surgical masks (mask rosacea).^53,54

DERMATOSES REVEALED OR AGGRAVATED BY COVID-19

Exacerbation of various skin diseases has been reported after infection with SARS-CoV-2.⁵⁵ Psoriasis and acrodermatitis continua of Hallopeau,⁵⁶ which may progress into generalized, pustular, or erythrodermic forms,⁵⁷ have been reported; the role of hydroxychloroquine and oral corticosteroids used for the treatment of COVID-19 has been suspected.⁵⁷ Atopic dermatitis patients—26% to 43%—have experienced worsening of their disease after symptomatic COVID-19 infection.⁵⁸ The incidence of herpesvirus infections, including herpes zoster, increased during the pandemic.⁵⁹ Alopecia areata relapses occurred in 42.5% of 392 patients with preexisting disease within 2 months of COVID-19 onset in one study,⁶⁰ possibly favored by the psychological stress; however, some studies have not confirmed the aggravating role of COVID-19 on alopecia areata.⁶¹ Lupus erythematosus, which may relapse in the form of Rowell syndrome,⁶² and livedoid vasculopathy⁶³ also have been reported following COVID-19 infection.

SKIN MANIFESTATIONS ASSOCIATED WITH COVID-19 VACCINES

In parallel with the rapid spread of COVID-19 vaccination,⁴ an increasing number of skin manifestations has been observed following vaccination; these dermatoses now are more frequently reported than those related to natural SARS-CoV-2 infection.^64-70 Vaccine-induced skin manifestations have a reported incidence of approximately 4% and show a female predominance.⁶⁵ Most of them (79%) have been reported in association with messenger RNA (mRNA)–based vaccines, which have been the most widely used; however, the frequency of side effects would be lower after mRNA vaccines than after inactivated virus-based vaccines. Eighteen percent occurred after the adenoviral vector vaccine, and 3% after the inactivated virus vaccine.⁷⁰ Fifty-nine percent were observed after the first dose. They are clinically polymorphous and generally benign, regressing spontaneously after a few days, and they should not constitute a contraindication to vaccination.Interestingly, many skin manifestations are similar to those associated with natural SARS-CoV-2 infection; however, their frequency and severity does not seem to depend on whether the patients had developed skin reactions during prior SARS-CoV-2 infection. These reactions have been classified into several types:

• Immediate local reactions at the injection site: pain, erythema, or edema represent the vast majority (96%) of reactions to vaccines. They appear within 7 days after vaccination (average, 1 day), slightly more frequently (59%) after the first dose. They concern mostly young patients and are benign, regressing in 2 to 3 days.⁷⁰
 

• Delayed local reactions: characterized by pain or pruritus, erythema, and skin induration mimicking cellulitis (COVID arm) and represent 1.7% of postvaccination reactions. They correspond to a delayed hypersensitivity reaction and appear approximately 7 days after vaccination, most often after the first vaccine dose (75% of cases), which is almost invariably mRNA based.⁷⁰

• Urticarial reactions corresponding to an immediate (type 1) hypersensitivity reaction: constitute 1% of postvaccination reactions, probably due to an allergy to vaccine ingredients. They appear on average 1 day after vaccination, almost always with mRNA vaccines.⁷⁰

• Angioedema: characterized by mucosal or subcutaneous edema and constitutes 0.5% of postvaccination reactions. It is a potentially serious reaction that appears on average 12 hours after vaccination, always with an mRNA-based vaccine.⁷⁰

• Morbilliform rash: represents delayed hypersensitivity reactions (0.1% of postvaccination reactions) that appear mostly after the first dose (72%), on average 3 days after vaccination, always with an mRNA-based vaccine.⁷⁰

• Herpes zoster: usually develops after the first vaccine dose in elderly patients (69% of cases) on average 4 days after vaccination and constitutes 0.1% of postvaccination reactions.⁷¹

• Bullous diseases: mainly bullous pemphigoid (90%) and more rarely pemphigus (5%) or bullous erythema pigmentosum (5%). They appear in elderly patients on average 7 days after vaccination and constitute 0.04% of postvaccination reactions.⁷²

• Chilblainlike lesions: several such cases have been reported so far⁷³; they constitute 0.03% of postvaccination reactions.⁷⁰ Clinically, they are similar to those associated with natural COVID-19; they appear mostly after the first dose (64%), on average 5 days after vaccination with the mRNA or adenovirus vaccine, and show a female predominance. The appearance of these lesions in vaccinated patients, who are a priori not carriers of the virus, strongly suggests that CBLLs are due to the immune reaction against SARS-CoV-2 rather than to a direct effect of this virus on the skin, which also is a likely scenario with regards to other skin manifestations seen during the successive COVID-19 epidemic waves.^73-75

• Reactions to hyaluronic acid–containing cosmetic fillers: erythema, edema, and potentially painful induration at the filler injection sites. They constitute 0.04% of postvaccination skin reactions and appear 24 hours after vaccination with mRNA-based vaccines, equally after the first or second dose.⁷⁶

• Pityriasis rosea–like rash: most occur after the second dose of mRNA-based vaccines (0.023% of postvaccination skin reactions).⁷⁰

• Severe reactions: these include acute generalized exanthematous pustulosis⁷⁷ and Stevens-Johnson syndrome.⁷⁸ One case of each has been reported after the adenoviral vector vaccine 3 days after vaccination.

Other more rarely observed manifestations include reactivation/aggravation or de novo appearance of inflammatory dermatoses such as psoriasis,^79,80 leukocytoclastic vasculitis,^81,82 lymphocytic⁸³ or urticarial⁸⁴ vasculitis, Sweet syndrome,⁸⁵ lupus erythematosus, dermatomyositis,^86,87 alopecia,^37,88 infection with Trichophyton rubrum,⁸⁹ Grover disease,⁹⁰ and lymphomatoid reactions (such as recurrences of cutaneous T-cell lymphomas [CD30⁺], and de novo development of lymphomatoid papulosis).⁹¹

FINAL THOUGHTS

COVID-19 is associated with several skin manifestations, even though the causative role of SARS-CoV-2 has remained elusive. These dermatoses are highly polymorphous, mostly benign, and usually spontaneously regressive, but some of them reflect severe infection. They mostly were described during the first pandemic waves, reported in several national and international registries, which allowed for their morphological classification. Currently, cutaneous adverse effects of vaccines are the most frequently reported dermatoses associated with SARS-CoV-2, and it is likely that they will continue to be observed while COVID-19 vaccination lasts. Hopefully the end of the COVID-19 pandemic is near. In January 2023, the International Health Regulations Emergency Committee of the World Health Organization acknowledged that the COVID-19 pandemic may be approaching an inflexion point, and even though the event continues to constitute a public health emergency of international concern, the higher levels of population immunity achieved globally through infection and/or vaccination may limit the impact of SARS-CoV-2 on morbidity and mortality. However, there is little doubt that this virus will remain a permanently established pathogen in humans and animals for the foreseeable future.⁹² Therefore, physicians—especially dermatologists—should be aware of the various skin manifestations associated with COVID-19 so they can more efficiently manage their patients.

COVID-19 is a potentially severe systemic disease caused by SARS-CoV-2. SARS-CoV and Middle East respiratory syndrome (MERS-CoV) caused fatal epidemics in Asia in 2002 to 2003 and in the Arabian Peninsula in 2012, respectively. In 2019, SARS-CoV-2 was detected in patients with severe, sometimes fatal pneumonia of previously unknown origin; it rapidly spread around the world, and the World Health Organization declared the disease a pandemic on March 11, 2020. SARS-CoV-2 is a β-coronavirus that is genetically related to the bat coronavirus and SARS-CoV; it is a single-stranded RNA virus of which several variants and subvariants exist. The SARS-CoV-2 viral particles bind via their surface spike protein (S protein) to the angiotensin-converting enzyme 2 receptor present on the membrane of several cell types, including epidermal and adnexal keratinocytes.^1,2 The α and δ variants, predominant from 2020 to 2021, mainly affected the lower respiratory tract and caused severe, potentially fatal pneumonia, especially in patients older than 65 years and/or with comorbidities, such as obesity, hypertension, diabetes, and (iatrogenic) immunosuppression. The ο variant, which appeared in late 2021, is more contagious than the initial variants, but it causes a less severe disease preferentially affecting the upper respiratory airways.³ As of April 5, 2023, more than 762,000,000 confirmed cases of COVID-19 have been recorded worldwide, causing more than 6,800,000 deaths.⁴

Early studies from China describing the symptoms of COVID-19 reported a low frequency of skin manifestations (0.2%), probably because they were focused on the most severe disease symptoms.⁵ Subsequently, when COVID-19 spread to the rest of the world, an increasing number of skin manifestations were reported in association with the disease. After the first publication from northern Italy in spring 2020, which was specifically devoted to skin manifestations of COVID-19,⁶ an explosive number of publications reported a large number of skin manifestations, and national registries were established in several countries to record these manifestations, such as the American Academy of Dermatology and the International League of Dermatological Societies registry,^7,8 the COVIDSKIN registry of the French Dermatology Society,⁹ and the Italian registry.¹⁰ Highlighting the unprecedented number of scientific articles published on this new disease, a PubMed search of articles indexed for MEDLINE search using the terms SARS-CoV-2 or COVID-19, on April 6, 2023, revealed 351,596 articles; that is more than 300 articles published every day in this database alone, with a large number of them concerning the skin.

SKIN DISEASSES ASSOCIATED WITH COVID-19

There are several types of COVID-19–related skin manifestations, depending on the circumstances of onset and the evolution of the pandemic.

Skin Manifestations Associated With SARS-CoV-2 Infection

The estimated incidence varies greatly according to the published series of patients, possibly depending on the geographic location. The estimated incidence seems lower in Asian countries, such as China (0.2%)⁵ and Japan (0.56%),¹¹ compared with Europe (up to 20%).⁶ Skin manifestations associated with SARS-CoV-2 infection affect individuals of all ages, slightly more females, and are clinically polymorphous; some of them are associated with the severity of the infection.¹² They may precede, accompany, or appear after the symptoms of COVID-19, most often within a month of the infection, of which they rarely are the only manifestation; however, their precise relationship to SARS-CoV-2 is not always well known. They have been classified according to their clinical presentation into several forms.^13-15

Morbilliform Maculopapular Eruption—Representing 16% to 53% of skin manifestations, morbilliform and maculopapular eruptions usually appear within 15 days of infection; they manifest with more or less confluent erythematous macules that may be hemorrhagic/petechial, and usually are asymptomatic and rarely pruritic. The rash mainly affects the trunk and limbs, sparing the face, palmoplantar regions, and mucous membranes; it appears concomitantly with or a few days after the first symptoms of COVID-19 (eg, fever, respiratory symptoms), regresses within a few days, and does not appear to be associated with disease severity. The distinction from maculopapular drug eruptions may be subtle. Histologically, the rash manifests with a spongiform dermatitis (ie, variable parakeratosis; spongiosis; and a mixed dermal perivascular infiltrate of lymphocytes, eosinophils and histiocytes, depending on the lesion age)(Figure 1). The etiopathogenesis is unknown; it may involve immune complexes to SARS-CoV-2 deposited on skin vessels. Treatment is not mandatory; if necessary, local or systemic corticosteroids may be used.

Vesicular (Pseudovaricella) Rash—This rash accounts for 11% to 18% of all skin manifestations and usually appears within 15 days of COVID-19 onset. It manifests with small monomorphous or varicellalike (pseudopolymorphic) vesicles appearing on the trunk, usually in young patients. The vesicles may be herpetiform, hemorrhagic, or pruritic, and appear before or within 3 days of the onset of mild COVID-19 symptoms; they regress within a few days without scarring. Histologically, the lesions show basal cell vacuolization; multinucleated, dyskeratotic/apoptotic or ballooning/acantholytic epidermal keratinocytes; reticular degeneration of the epidermis; intraepidermal vesicles sometimes resembling herpetic vesicular infections or Grover disease; and mild dermal inflammation. There is no specific treatment.

Urticaria—Urticarial rash, or urticaria, represents 5% to 16% of skin manifestations; usually appears within 15 days of disease onset; and manifests with pruritic, migratory, edematous papules appearing mainly on the trunk and occasionally the face and limbs. The urticarial rash tends to be associated with more severe forms of the disease and regresses within a week, responding to antihistamines. Of note, clinically similar rashes can be caused by drugs. Histologically, the lesions show dermal edema and a mild perivascular lymphocytic infiltrate, sometimes admixed with eosinophils.

Chilblainlike Lesions—Chilblainlike lesions (CBLLs) account for 19% of skin manifestations associated with COVID-19¹³ and present as erythematous-purplish, edematous lesions that can be mildly pruritic or painful, appearing on the toes—COVID toes—and more rarely the fingers (Figure 2). They were seen epidemically during the first pandemic wave (2020 lockdown) in several countries, and clinically are very similar to, if not indistinguishable from, idiopathic chilblains, but are not necessarily associated with cold exposure. They appear in young, generally healthy patients or those with mild COVID-19 symptoms 2 to 4 weeks after symptom onset. They regress spontaneously or under local corticosteroid treatment within a few days or weeks. Histologically, CBLLs are indistinguishable from chilblains of other origins, namely idiopathic (seasonal) ones. They manifest with necrosis of epidermal keratinocytes; dermal edema that may be severe, leading to the development of subepidermal pseudobullae; a rather dense perivascular and perieccrine gland lymphocytic infiltrate; and sometimes with vascular lesions (eg, edema of endothelial cells, microthromboses of dermal capillaries and venules, fibrinoid deposits within the wall of dermal venules)(Figure 3).^16-18 Most patients (>80%) with CBLLs have negative serologic or polymerase chain reaction tests for SARS-CoV-2,¹⁹ which generated a lively debate about the role of SARS-CoV-2 in the genesis of CBLLs. According to some authors, SARS-CoV-2 plays no direct role, and CBLLs would occur in young people who sit or walk barefoot on cold floors at home during confinement.^20-23 Remarkably, CBLLs appeared in patients with no history of chilblains during a season that was not particularly cold, namely in France or in southern California, where their incidence was much higher compared to the same time period of prior years. Some reports have supported a direct role for the virus based on questionable observations of the virus within skin lesions (eg, sweat glands, endothelial cells) by immunohistochemistry, electron microscopy, and/or in situ hybridization.^17,24,25 A more satisfactory hypothesis would involve the role of a strong innate immunity leading to elimination of the virus before the development of specific antibodies via the increased production of type 1 interferon (IFN-1); this would affect the vessels, causing CBLLs. This mechanism would be similar to the one observed in some interferonopathies (eg, Aicardi-Goutières syndrome), also characterized by IFN-1 hypersecretion and chilblains.^26-29 According to this hypothesis, CBLLs should be considered a paraviral rash similar to other skin manifestations associated with COVID-19.³⁰

Acro-ischemia—Acro-ischemia livedoid lesions account for 1% to 6% of skin manifestations and comprise lesions of livedo (either reticulated or racemosa); necrotic acral bullae; and gangrenous necrosis of the extremities, especially the toes. The livedoid lesions most often appear within 15 days of COVID-19 symptom onset, and the purpuric lesions somewhat later (2–4 weeks); they mainly affect adult patients, last about 10 days, and are the hallmark of severe infection, presumably related to microthromboses of the cutaneous capillaries (endothelial dysfunction, prothrombotic state, elevated D-dimers). Histologically, they show capillary thrombosis and dermoepidermal necrosis (Figure 4).

Other Reported Polymorphic or Atypical Rashes—Erythema multiforme–like eruptions may appear before other COVID-19 symptoms and manifest as reddish-purple, nearly symmetric, diffuse, occasionally targetoid bullous or necrotic macules. The eruptions mainly affect adults and most often are seen on the palms, elbows, knees, and sometimes the mucous membranes. The rash regresses in 1 to 3 weeks without scarring and represents a delayed cutaneous hypersensitivity reaction. Histologically, the lesions show vacuolization of basal epidermal keratinocytes, keratinocyte necrosis, dermoepidermal detachment, a variably dense dermal T-lymphocytic infiltrate, and red blood cell extravasation (Figure 5).

Leukocytoclastic vasculitis may be generalized or localized. It manifests clinically by petechial/purpuric maculopapules, especially on the legs, mainly in elderly patients with COVID-19. Histologically, the lesions show necrotizing changes of dermal postcapillary venules, neutrophilic perivascular inflammation, red blood cell extravasation, and occasionally vascular IgA deposits by direct immunofluorescence examination. The course usually is benign.

The incidence of pityriasis rosea and of clinically similar rashes (referred to as “pityriasis rosea–like”) increased 5-fold during the COVID-19 pandemic.^31,32 These dermatoses manifest with erythematous, scaly, circinate plaques, typically with an initial herald lesion followed a few days later by smaller erythematous macules. Histologically, the lesions comprise a spongiform dermatitis with intraepidermal exocytosis of red blood cells and a mild to moderate dermal lymphocytic infiltrate.

Erythrodysesthesia, or hand-foot syndrome, manifests with edematous erythema and palmoplantar desquamation accompanied by a burning sensation or pain. This syndrome is known as an adverse effect of some chemotherapies because of the associated drug toxicity and sweat gland inflammation; it was observed in 40% of 666 COVID-19–positive patients with mild to moderate pneumonitis.³³

“COVID nose” is a rare cutaneous manifestation characterized by nasal pigmentation comprising multiple coalescent frecklelike macules on the tip and wings of the nose and sometimes the malar areas. These lesions predominantly appear in women aged 25 to 65 years and show on average 23 days after onset of COVID-19, which is usually mild. This pigmentation is similar to pigmentary changes after infection with chikungunya; it can be treated with depigmenting products such as azelaic acid and hydroquinone cream with sunscreen use, and it regresses in 2 to 4 months.³⁴

Telogen effluvium (excessive and temporary shedding of normal telogen club hairs of the entire scalp due to the disturbance of the hair cycle) is reportedly frequent in patients (48%) 1 month after COVID-19 infection, but it may appear later (after 12 weeks).³⁵ Alopecia also is frequently reported during long (or postacute) COVID-19 (ie, the symptomatic disease phase past the acute 4 weeks’ stage of the infection) and shows a female predominance³⁶; it likely represents the telogen effluvium seen 90 days after a severe illness. Trichodynia (pruritus, burning, pain, or paresthesia of the scalp) also is reportedly common (developing in more than 58% of patients) and is associated with telogen effluvium in 44% of cases. Several cases of alopecia areata (AA) triggered or aggravated by COVID-19 also have been reported^37,38; they could be explained by the “cytokine storm” triggered by the infection, involving T and B lymphocytes; plasmacytoid dendritic cells; natural killer cells with oversecretion of IL-6, IL-4, tumor necrosis factor α, and IFN type I; and a cytotoxic reaction associated with loss of the immune privilege of hair follicles.

Nail Manifestations

The red half-moon nail sign is an asymptomatic purplish-red band around the distal margin of the lunula that affects some adult patients with COVID-19.³⁹ It appears shortly after onset of symptoms, likely the manifestation of vascular inflammation in the nail bed, and regresses slowly after approximately 1 week.⁴⁰ Beau lines are transverse grooves in the nail plate due to the temporary arrest of the proximal nail matrix growth accompanying systemic illnesses; they appear approximately 2 to 3 weeks after the onset of COVID-19.⁴¹ Furthermore, nail alterations can be caused by drugs used to treat COVID-19, such as longitudinal melanonychia due to treatment with hydroxychloroquine or fluorescence of the lunula or nail plate due to treatment with favipiravir.⁴²

Multisystem Inflammatory Syndrome

Multisystem inflammatory syndrome (MIS) is clinically similar to Kawasaki disease; it typically affects children⁴³ and more rarely adults with COVID-19. It manifests with fever, weakness, and biological inflammation and also frequently with skin lesions (72%), which are polymorphous and include morbilliform rash (27%); urticaria (24%); periorbital edema (24%); nonspecific erythema (21.2%); retiform purpura (18%); targetoid lesions (15%); malar rash (15.2%); and periareolar erythema (6%).⁴⁴ Compared to Kawasaki disease, MIS affects slightly older children (mean age, 8.5 vs 3 years) and more frequently includes cardiac and gastrointestinal manifestations; the mortality rate also is slightly higher (2% vs 0.17%).⁴⁵

Confirmed COVID-19 Infection

At the beginning of the pandemic, skin manifestations were reported in patients who were suspected of having COVID-19 but did not always have biological confirmation of SARS-CoV-2 infection due to the unavailability of diagnostic tests or the physical impossibility of testing. However, subsequent studies have confirmed that most of these dermatoses were indeed associated with COVID-19 infection.^9,46 For example, a study of 655 patients with confirmed COVID-19 infection reported maculopapular (38%), vascular (22%), urticarial (15%), and vesicular (15%) rashes; erythema multiforme or Stevens-Johnson–like syndrome (3%, often related to the use of hydroxychloroquine); generalized pruritus (1%); and MIS (0.5%). The study confirmed that CBLLs were mostly seen in young patients with mild disease, whereas livedo (fixed rash) and retiform purpura occurred in older patients with a guarded prognosis.⁴⁶

Remarkably, most dermatoses associated with SARS-CoV-2 infection were reported during the initial waves of the pandemic, which were due to the α and δ viral variants. These manifestations were reported more rarely when the ο variant was predominant, even though most patients (63%) who developed CBLLs in the first wave also developed them during the second pandemic wave.⁴⁷ This decrease in the incidence of COVID-19–associated dermatoses could be because of the lower pathogenicity of the o variant,³ a lower tropism for the skin, and variations in SARS-CoV-2 antigenicity that would induce a different immunologic response, combined with an increasingly stronger herd immunity compared to the first pandemic waves achieved through vaccination and spontaneous infections in the population. Additional reasons may include different baseline characteristics in patients hospitalized with COVID-19 (regarding comorbidities, disease severity, and received treatments), and the possibility that some of the initially reported COVID-19–associated skin manifestations could have been produced by different etiologic agents.⁴⁸ In the last 2 years, COVID-19–related skin manifestations have been reported mainly as adverse events to COVID-19 vaccination.

CUTANEOUS ADVERSE EFFECTS OF DRUGS USED TO TREAT COVID-19

Prior to the advent of vaccines and specific treatments for SARS-CoV-2, various drugs were used—namely hydroxychloroquine, ivermectin, and tocilizumab—that did not prove efficacious and caused diverse adverse effects, including cutaneous eruptions such as urticaria, maculopapular eruptions, erythema multiforme or Stevens-Johnson syndrome, vasculitis, longitudinal melanonychia, and acute generalized exanthematous pustulosis.^49,50 Nirmatrelvir 150 mg–ritonavir 100 mg, which was authorized for emergency use by the US Food and Drug Administration for the treatment of COVID-19, is a viral protease inhibitor blocking the replication of the virus. Ritonavir can induce pruritus, maculopapular rash, acne, Stevens-Johnson syndrome, and toxic epidermal necrolysis; of note, these effects have been observed following administration of ritonavir for treatment of HIV at higher daily doses and for much longer periods of time compared with treatment of COVID-19 (600–1200 mg vs 200 mg/d, respectively). These cutaneous drug side effects are clinically similar to the manifestations caused either directly or indirectly by SARS-CoV-2 infection; therefore, it may be difficult to differentiate them.

DERMATOSES DUE TO PROTECTIVE DEVICES

Dermatoses due to personal protective equipment such as masks or face shields affected the general population and mostly health care professionals⁵¹; 54.4% of 879 health care professionals in one study reported such events.⁵² These dermatoses mainly include contact dermatitis of the face (nose, forehead, and cheeks) of irritant or allergic nature (eg, from preservatives releasing formaldehyde contained in masks and protective goggles). They manifest with skin dryness; desquamation; maceration; fissures; or erosions or ulcerations of the cheeks, forehead, and nose. Cases of pressure urticaria also have been reported. Irritant dermatitis induced by the frequent use of disinfectants (eg, soaps, hydroalcoholic sanitizing gels) also can affect the hands. Allergic hand dermatitis can be caused by medical gloves.

The term maskne (or mask acne) refers to a variety of mechanical acne due to the prolonged use of surgical masks (>4 hours per day for ≥6 weeks); it includes cases of de novo acne and cases of pre-existing acne aggravated by wearing a mask. Maskne is characterized by acne lesions located on the facial area covered by the mask (Figure 6). It is caused by follicular occlusion; increased sebum secretion; mechanical stress (pressure, friction); and dysbiosis of the microbiome induced by changes in heat, pH, and humidity. Preventive measures include application of noncomedogenic moisturizers or gauze before wearing the mask as well as facial cleansing with appropriate nonalcoholic products. Similar to acne, rosacea often is aggravated by prolonged wearing of surgical masks (mask rosacea).^53,54

DERMATOSES REVEALED OR AGGRAVATED BY COVID-19

Exacerbation of various skin diseases has been reported after infection with SARS-CoV-2.⁵⁵ Psoriasis and acrodermatitis continua of Hallopeau,⁵⁶ which may progress into generalized, pustular, or erythrodermic forms,⁵⁷ have been reported; the role of hydroxychloroquine and oral corticosteroids used for the treatment of COVID-19 has been suspected.⁵⁷ Atopic dermatitis patients—26% to 43%—have experienced worsening of their disease after symptomatic COVID-19 infection.⁵⁸ The incidence of herpesvirus infections, including herpes zoster, increased during the pandemic.⁵⁹ Alopecia areata relapses occurred in 42.5% of 392 patients with preexisting disease within 2 months of COVID-19 onset in one study,⁶⁰ possibly favored by the psychological stress; however, some studies have not confirmed the aggravating role of COVID-19 on alopecia areata.⁶¹ Lupus erythematosus, which may relapse in the form of Rowell syndrome,⁶² and livedoid vasculopathy⁶³ also have been reported following COVID-19 infection.

SKIN MANIFESTATIONS ASSOCIATED WITH COVID-19 VACCINES

In parallel with the rapid spread of COVID-19 vaccination,⁴ an increasing number of skin manifestations has been observed following vaccination; these dermatoses now are more frequently reported than those related to natural SARS-CoV-2 infection.^64-70 Vaccine-induced skin manifestations have a reported incidence of approximately 4% and show a female predominance.⁶⁵ Most of them (79%) have been reported in association with messenger RNA (mRNA)–based vaccines, which have been the most widely used; however, the frequency of side effects would be lower after mRNA vaccines than after inactivated virus-based vaccines. Eighteen percent occurred after the adenoviral vector vaccine, and 3% after the inactivated virus vaccine.⁷⁰ Fifty-nine percent were observed after the first dose. They are clinically polymorphous and generally benign, regressing spontaneously after a few days, and they should not constitute a contraindication to vaccination.Interestingly, many skin manifestations are similar to those associated with natural SARS-CoV-2 infection; however, their frequency and severity does not seem to depend on whether the patients had developed skin reactions during prior SARS-CoV-2 infection. These reactions have been classified into several types:

• Immediate local reactions at the injection site: pain, erythema, or edema represent the vast majority (96%) of reactions to vaccines. They appear within 7 days after vaccination (average, 1 day), slightly more frequently (59%) after the first dose. They concern mostly young patients and are benign, regressing in 2 to 3 days.⁷⁰
 

• Delayed local reactions: characterized by pain or pruritus, erythema, and skin induration mimicking cellulitis (COVID arm) and represent 1.7% of postvaccination reactions. They correspond to a delayed hypersensitivity reaction and appear approximately 7 days after vaccination, most often after the first vaccine dose (75% of cases), which is almost invariably mRNA based.⁷⁰

• Urticarial reactions corresponding to an immediate (type 1) hypersensitivity reaction: constitute 1% of postvaccination reactions, probably due to an allergy to vaccine ingredients. They appear on average 1 day after vaccination, almost always with mRNA vaccines.⁷⁰

• Angioedema: characterized by mucosal or subcutaneous edema and constitutes 0.5% of postvaccination reactions. It is a potentially serious reaction that appears on average 12 hours after vaccination, always with an mRNA-based vaccine.⁷⁰

• Morbilliform rash: represents delayed hypersensitivity reactions (0.1% of postvaccination reactions) that appear mostly after the first dose (72%), on average 3 days after vaccination, always with an mRNA-based vaccine.⁷⁰

• Herpes zoster: usually develops after the first vaccine dose in elderly patients (69% of cases) on average 4 days after vaccination and constitutes 0.1% of postvaccination reactions.⁷¹

• Bullous diseases: mainly bullous pemphigoid (90%) and more rarely pemphigus (5%) or bullous erythema pigmentosum (5%). They appear in elderly patients on average 7 days after vaccination and constitute 0.04% of postvaccination reactions.⁷²

• Chilblainlike lesions: several such cases have been reported so far⁷³; they constitute 0.03% of postvaccination reactions.⁷⁰ Clinically, they are similar to those associated with natural COVID-19; they appear mostly after the first dose (64%), on average 5 days after vaccination with the mRNA or adenovirus vaccine, and show a female predominance. The appearance of these lesions in vaccinated patients, who are a priori not carriers of the virus, strongly suggests that CBLLs are due to the immune reaction against SARS-CoV-2 rather than to a direct effect of this virus on the skin, which also is a likely scenario with regards to other skin manifestations seen during the successive COVID-19 epidemic waves.^73-75

• Reactions to hyaluronic acid–containing cosmetic fillers: erythema, edema, and potentially painful induration at the filler injection sites. They constitute 0.04% of postvaccination skin reactions and appear 24 hours after vaccination with mRNA-based vaccines, equally after the first or second dose.⁷⁶

• Pityriasis rosea–like rash: most occur after the second dose of mRNA-based vaccines (0.023% of postvaccination skin reactions).⁷⁰

• Severe reactions: these include acute generalized exanthematous pustulosis⁷⁷ and Stevens-Johnson syndrome.⁷⁸ One case of each has been reported after the adenoviral vector vaccine 3 days after vaccination.

Other more rarely observed manifestations include reactivation/aggravation or de novo appearance of inflammatory dermatoses such as psoriasis,^79,80 leukocytoclastic vasculitis,^81,82 lymphocytic⁸³ or urticarial⁸⁴ vasculitis, Sweet syndrome,⁸⁵ lupus erythematosus, dermatomyositis,^86,87 alopecia,^37,88 infection with Trichophyton rubrum,⁸⁹ Grover disease,⁹⁰ and lymphomatoid reactions (such as recurrences of cutaneous T-cell lymphomas [CD30⁺], and de novo development of lymphomatoid papulosis).⁹¹

FINAL THOUGHTS

COVID-19 is associated with several skin manifestations, even though the causative role of SARS-CoV-2 has remained elusive. These dermatoses are highly polymorphous, mostly benign, and usually spontaneously regressive, but some of them reflect severe infection. They mostly were described during the first pandemic waves, reported in several national and international registries, which allowed for their morphological classification. Currently, cutaneous adverse effects of vaccines are the most frequently reported dermatoses associated with SARS-CoV-2, and it is likely that they will continue to be observed while COVID-19 vaccination lasts. Hopefully the end of the COVID-19 pandemic is near. In January 2023, the International Health Regulations Emergency Committee of the World Health Organization acknowledged that the COVID-19 pandemic may be approaching an inflexion point, and even though the event continues to constitute a public health emergency of international concern, the higher levels of population immunity achieved globally through infection and/or vaccination may limit the impact of SARS-CoV-2 on morbidity and mortality. However, there is little doubt that this virus will remain a permanently established pathogen in humans and animals for the foreseeable future.⁹² Therefore, physicians—especially dermatologists—should be aware of the various skin manifestations associated with COVID-19 so they can more efficiently manage their patients.

COVID-19 is a potentially severe systemic disease caused by SARS-CoV-2. SARS-CoV and Middle East respiratory syndrome (MERS-CoV) caused fatal epidemics in Asia in 2002 to 2003 and in the Arabian Peninsula in 2012, respectively. In 2019, SARS-CoV-2 was detected in patients with severe, sometimes fatal pneumonia of previously unknown origin; it rapidly spread around the world, and the World Health Organization declared the disease a pandemic on March 11, 2020. SARS-CoV-2 is a β-coronavirus that is genetically related to the bat coronavirus and SARS-CoV; it is a single-stranded RNA virus of which several variants and subvariants exist. The SARS-CoV-2 viral particles bind via their surface spike protein (S protein) to the angiotensin-converting enzyme 2 receptor present on the membrane of several cell types, including epidermal and adnexal keratinocytes.^1,2 The α and δ variants, predominant from 2020 to 2021, mainly affected the lower respiratory tract and caused severe, potentially fatal pneumonia, especially in patients older than 65 years and/or with comorbidities, such as obesity, hypertension, diabetes, and (iatrogenic) immunosuppression. The ο variant, which appeared in late 2021, is more contagious than the initial variants, but it causes a less severe disease preferentially affecting the upper respiratory airways.³ As of April 5, 2023, more than 762,000,000 confirmed cases of COVID-19 have been recorded worldwide, causing more than 6,800,000 deaths.⁴

Early studies from China describing the symptoms of COVID-19 reported a low frequency of skin manifestations (0.2%), probably because they were focused on the most severe disease symptoms.⁵ Subsequently, when COVID-19 spread to the rest of the world, an increasing number of skin manifestations were reported in association with the disease. After the first publication from northern Italy in spring 2020, which was specifically devoted to skin manifestations of COVID-19,⁶ an explosive number of publications reported a large number of skin manifestations, and national registries were established in several countries to record these manifestations, such as the American Academy of Dermatology and the International League of Dermatological Societies registry,^7,8 the COVIDSKIN registry of the French Dermatology Society,⁹ and the Italian registry.¹⁰ Highlighting the unprecedented number of scientific articles published on this new disease, a PubMed search of articles indexed for MEDLINE search using the terms SARS-CoV-2 or COVID-19, on April 6, 2023, revealed 351,596 articles; that is more than 300 articles published every day in this database alone, with a large number of them concerning the skin.

SKIN DISEASSES ASSOCIATED WITH COVID-19

There are several types of COVID-19–related skin manifestations, depending on the circumstances of onset and the evolution of the pandemic.

Skin Manifestations Associated With SARS-CoV-2 Infection

The estimated incidence varies greatly according to the published series of patients, possibly depending on the geographic location. The estimated incidence seems lower in Asian countries, such as China (0.2%)⁵ and Japan (0.56%),¹¹ compared with Europe (up to 20%).⁶ Skin manifestations associated with SARS-CoV-2 infection affect individuals of all ages, slightly more females, and are clinically polymorphous; some of them are associated with the severity of the infection.¹² They may precede, accompany, or appear after the symptoms of COVID-19, most often within a month of the infection, of which they rarely are the only manifestation; however, their precise relationship to SARS-CoV-2 is not always well known. They have been classified according to their clinical presentation into several forms.^13-15

Morbilliform Maculopapular Eruption—Representing 16% to 53% of skin manifestations, morbilliform and maculopapular eruptions usually appear within 15 days of infection; they manifest with more or less confluent erythematous macules that may be hemorrhagic/petechial, and usually are asymptomatic and rarely pruritic. The rash mainly affects the trunk and limbs, sparing the face, palmoplantar regions, and mucous membranes; it appears concomitantly with or a few days after the first symptoms of COVID-19 (eg, fever, respiratory symptoms), regresses within a few days, and does not appear to be associated with disease severity. The distinction from maculopapular drug eruptions may be subtle. Histologically, the rash manifests with a spongiform dermatitis (ie, variable parakeratosis; spongiosis; and a mixed dermal perivascular infiltrate of lymphocytes, eosinophils and histiocytes, depending on the lesion age)(Figure 1). The etiopathogenesis is unknown; it may involve immune complexes to SARS-CoV-2 deposited on skin vessels. Treatment is not mandatory; if necessary, local or systemic corticosteroids may be used.

Vesicular (Pseudovaricella) Rash—This rash accounts for 11% to 18% of all skin manifestations and usually appears within 15 days of COVID-19 onset. It manifests with small monomorphous or varicellalike (pseudopolymorphic) vesicles appearing on the trunk, usually in young patients. The vesicles may be herpetiform, hemorrhagic, or pruritic, and appear before or within 3 days of the onset of mild COVID-19 symptoms; they regress within a few days without scarring. Histologically, the lesions show basal cell vacuolization; multinucleated, dyskeratotic/apoptotic or ballooning/acantholytic epidermal keratinocytes; reticular degeneration of the epidermis; intraepidermal vesicles sometimes resembling herpetic vesicular infections or Grover disease; and mild dermal inflammation. There is no specific treatment.

Urticaria—Urticarial rash, or urticaria, represents 5% to 16% of skin manifestations; usually appears within 15 days of disease onset; and manifests with pruritic, migratory, edematous papules appearing mainly on the trunk and occasionally the face and limbs. The urticarial rash tends to be associated with more severe forms of the disease and regresses within a week, responding to antihistamines. Of note, clinically similar rashes can be caused by drugs. Histologically, the lesions show dermal edema and a mild perivascular lymphocytic infiltrate, sometimes admixed with eosinophils.

Chilblainlike Lesions—Chilblainlike lesions (CBLLs) account for 19% of skin manifestations associated with COVID-19¹³ and present as erythematous-purplish, edematous lesions that can be mildly pruritic or painful, appearing on the toes—COVID toes—and more rarely the fingers (Figure 2). They were seen epidemically during the first pandemic wave (2020 lockdown) in several countries, and clinically are very similar to, if not indistinguishable from, idiopathic chilblains, but are not necessarily associated with cold exposure. They appear in young, generally healthy patients or those with mild COVID-19 symptoms 2 to 4 weeks after symptom onset. They regress spontaneously or under local corticosteroid treatment within a few days or weeks. Histologically, CBLLs are indistinguishable from chilblains of other origins, namely idiopathic (seasonal) ones. They manifest with necrosis of epidermal keratinocytes; dermal edema that may be severe, leading to the development of subepidermal pseudobullae; a rather dense perivascular and perieccrine gland lymphocytic infiltrate; and sometimes with vascular lesions (eg, edema of endothelial cells, microthromboses of dermal capillaries and venules, fibrinoid deposits within the wall of dermal venules)(Figure 3).^16-18 Most patients (>80%) with CBLLs have negative serologic or polymerase chain reaction tests for SARS-CoV-2,¹⁹ which generated a lively debate about the role of SARS-CoV-2 in the genesis of CBLLs. According to some authors, SARS-CoV-2 plays no direct role, and CBLLs would occur in young people who sit or walk barefoot on cold floors at home during confinement.^20-23 Remarkably, CBLLs appeared in patients with no history of chilblains during a season that was not particularly cold, namely in France or in southern California, where their incidence was much higher compared to the same time period of prior years. Some reports have supported a direct role for the virus based on questionable observations of the virus within skin lesions (eg, sweat glands, endothelial cells) by immunohistochemistry, electron microscopy, and/or in situ hybridization.^17,24,25 A more satisfactory hypothesis would involve the role of a strong innate immunity leading to elimination of the virus before the development of specific antibodies via the increased production of type 1 interferon (IFN-1); this would affect the vessels, causing CBLLs. This mechanism would be similar to the one observed in some interferonopathies (eg, Aicardi-Goutières syndrome), also characterized by IFN-1 hypersecretion and chilblains.^26-29 According to this hypothesis, CBLLs should be considered a paraviral rash similar to other skin manifestations associated with COVID-19.³⁰

Acro-ischemia—Acro-ischemia livedoid lesions account for 1% to 6% of skin manifestations and comprise lesions of livedo (either reticulated or racemosa); necrotic acral bullae; and gangrenous necrosis of the extremities, especially the toes. The livedoid lesions most often appear within 15 days of COVID-19 symptom onset, and the purpuric lesions somewhat later (2–4 weeks); they mainly affect adult patients, last about 10 days, and are the hallmark of severe infection, presumably related to microthromboses of the cutaneous capillaries (endothelial dysfunction, prothrombotic state, elevated D-dimers). Histologically, they show capillary thrombosis and dermoepidermal necrosis (Figure 4).

Other Reported Polymorphic or Atypical Rashes—Erythema multiforme–like eruptions may appear before other COVID-19 symptoms and manifest as reddish-purple, nearly symmetric, diffuse, occasionally targetoid bullous or necrotic macules. The eruptions mainly affect adults and most often are seen on the palms, elbows, knees, and sometimes the mucous membranes. The rash regresses in 1 to 3 weeks without scarring and represents a delayed cutaneous hypersensitivity reaction. Histologically, the lesions show vacuolization of basal epidermal keratinocytes, keratinocyte necrosis, dermoepidermal detachment, a variably dense dermal T-lymphocytic infiltrate, and red blood cell extravasation (Figure 5).

Leukocytoclastic vasculitis may be generalized or localized. It manifests clinically by petechial/purpuric maculopapules, especially on the legs, mainly in elderly patients with COVID-19. Histologically, the lesions show necrotizing changes of dermal postcapillary venules, neutrophilic perivascular inflammation, red blood cell extravasation, and occasionally vascular IgA deposits by direct immunofluorescence examination. The course usually is benign.

The incidence of pityriasis rosea and of clinically similar rashes (referred to as “pityriasis rosea–like”) increased 5-fold during the COVID-19 pandemic.^31,32 These dermatoses manifest with erythematous, scaly, circinate plaques, typically with an initial herald lesion followed a few days later by smaller erythematous macules. Histologically, the lesions comprise a spongiform dermatitis with intraepidermal exocytosis of red blood cells and a mild to moderate dermal lymphocytic infiltrate.

Erythrodysesthesia, or hand-foot syndrome, manifests with edematous erythema and palmoplantar desquamation accompanied by a burning sensation or pain. This syndrome is known as an adverse effect of some chemotherapies because of the associated drug toxicity and sweat gland inflammation; it was observed in 40% of 666 COVID-19–positive patients with mild to moderate pneumonitis.³³

“COVID nose” is a rare cutaneous manifestation characterized by nasal pigmentation comprising multiple coalescent frecklelike macules on the tip and wings of the nose and sometimes the malar areas. These lesions predominantly appear in women aged 25 to 65 years and show on average 23 days after onset of COVID-19, which is usually mild. This pigmentation is similar to pigmentary changes after infection with chikungunya; it can be treated with depigmenting products such as azelaic acid and hydroquinone cream with sunscreen use, and it regresses in 2 to 4 months.³⁴

Telogen effluvium (excessive and temporary shedding of normal telogen club hairs of the entire scalp due to the disturbance of the hair cycle) is reportedly frequent in patients (48%) 1 month after COVID-19 infection, but it may appear later (after 12 weeks).³⁵ Alopecia also is frequently reported during long (or postacute) COVID-19 (ie, the symptomatic disease phase past the acute 4 weeks’ stage of the infection) and shows a female predominance³⁶; it likely represents the telogen effluvium seen 90 days after a severe illness. Trichodynia (pruritus, burning, pain, or paresthesia of the scalp) also is reportedly common (developing in more than 58% of patients) and is associated with telogen effluvium in 44% of cases. Several cases of alopecia areata (AA) triggered or aggravated by COVID-19 also have been reported^37,38; they could be explained by the “cytokine storm” triggered by the infection, involving T and B lymphocytes; plasmacytoid dendritic cells; natural killer cells with oversecretion of IL-6, IL-4, tumor necrosis factor α, and IFN type I; and a cytotoxic reaction associated with loss of the immune privilege of hair follicles.

Nail Manifestations

The red half-moon nail sign is an asymptomatic purplish-red band around the distal margin of the lunula that affects some adult patients with COVID-19.³⁹ It appears shortly after onset of symptoms, likely the manifestation of vascular inflammation in the nail bed, and regresses slowly after approximately 1 week.⁴⁰ Beau lines are transverse grooves in the nail plate due to the temporary arrest of the proximal nail matrix growth accompanying systemic illnesses; they appear approximately 2 to 3 weeks after the onset of COVID-19.⁴¹ Furthermore, nail alterations can be caused by drugs used to treat COVID-19, such as longitudinal melanonychia due to treatment with hydroxychloroquine or fluorescence of the lunula or nail plate due to treatment with favipiravir.⁴²

Multisystem Inflammatory Syndrome

Multisystem inflammatory syndrome (MIS) is clinically similar to Kawasaki disease; it typically affects children⁴³ and more rarely adults with COVID-19. It manifests with fever, weakness, and biological inflammation and also frequently with skin lesions (72%), which are polymorphous and include morbilliform rash (27%); urticaria (24%); periorbital edema (24%); nonspecific erythema (21.2%); retiform purpura (18%); targetoid lesions (15%); malar rash (15.2%); and periareolar erythema (6%).⁴⁴ Compared to Kawasaki disease, MIS affects slightly older children (mean age, 8.5 vs 3 years) and more frequently includes cardiac and gastrointestinal manifestations; the mortality rate also is slightly higher (2% vs 0.17%).⁴⁵

Confirmed COVID-19 Infection

At the beginning of the pandemic, skin manifestations were reported in patients who were suspected of having COVID-19 but did not always have biological confirmation of SARS-CoV-2 infection due to the unavailability of diagnostic tests or the physical impossibility of testing. However, subsequent studies have confirmed that most of these dermatoses were indeed associated with COVID-19 infection.^9,46 For example, a study of 655 patients with confirmed COVID-19 infection reported maculopapular (38%), vascular (22%), urticarial (15%), and vesicular (15%) rashes; erythema multiforme or Stevens-Johnson–like syndrome (3%, often related to the use of hydroxychloroquine); generalized pruritus (1%); and MIS (0.5%). The study confirmed that CBLLs were mostly seen in young patients with mild disease, whereas livedo (fixed rash) and retiform purpura occurred in older patients with a guarded prognosis.⁴⁶

Remarkably, most dermatoses associated with SARS-CoV-2 infection were reported during the initial waves of the pandemic, which were due to the α and δ viral variants. These manifestations were reported more rarely when the ο variant was predominant, even though most patients (63%) who developed CBLLs in the first wave also developed them during the second pandemic wave.⁴⁷ This decrease in the incidence of COVID-19–associated dermatoses could be because of the lower pathogenicity of the o variant,³ a lower tropism for the skin, and variations in SARS-CoV-2 antigenicity that would induce a different immunologic response, combined with an increasingly stronger herd immunity compared to the first pandemic waves achieved through vaccination and spontaneous infections in the population. Additional reasons may include different baseline characteristics in patients hospitalized with COVID-19 (regarding comorbidities, disease severity, and received treatments), and the possibility that some of the initially reported COVID-19–associated skin manifestations could have been produced by different etiologic agents.⁴⁸ In the last 2 years, COVID-19–related skin manifestations have been reported mainly as adverse events to COVID-19 vaccination.

CUTANEOUS ADVERSE EFFECTS OF DRUGS USED TO TREAT COVID-19

Prior to the advent of vaccines and specific treatments for SARS-CoV-2, various drugs were used—namely hydroxychloroquine, ivermectin, and tocilizumab—that did not prove efficacious and caused diverse adverse effects, including cutaneous eruptions such as urticaria, maculopapular eruptions, erythema multiforme or Stevens-Johnson syndrome, vasculitis, longitudinal melanonychia, and acute generalized exanthematous pustulosis.^49,50 Nirmatrelvir 150 mg–ritonavir 100 mg, which was authorized for emergency use by the US Food and Drug Administration for the treatment of COVID-19, is a viral protease inhibitor blocking the replication of the virus. Ritonavir can induce pruritus, maculopapular rash, acne, Stevens-Johnson syndrome, and toxic epidermal necrolysis; of note, these effects have been observed following administration of ritonavir for treatment of HIV at higher daily doses and for much longer periods of time compared with treatment of COVID-19 (600–1200 mg vs 200 mg/d, respectively). These cutaneous drug side effects are clinically similar to the manifestations caused either directly or indirectly by SARS-CoV-2 infection; therefore, it may be difficult to differentiate them.

DERMATOSES DUE TO PROTECTIVE DEVICES

Dermatoses due to personal protective equipment such as masks or face shields affected the general population and mostly health care professionals⁵¹; 54.4% of 879 health care professionals in one study reported such events.⁵² These dermatoses mainly include contact dermatitis of the face (nose, forehead, and cheeks) of irritant or allergic nature (eg, from preservatives releasing formaldehyde contained in masks and protective goggles). They manifest with skin dryness; desquamation; maceration; fissures; or erosions or ulcerations of the cheeks, forehead, and nose. Cases of pressure urticaria also have been reported. Irritant dermatitis induced by the frequent use of disinfectants (eg, soaps, hydroalcoholic sanitizing gels) also can affect the hands. Allergic hand dermatitis can be caused by medical gloves.

The term maskne (or mask acne) refers to a variety of mechanical acne due to the prolonged use of surgical masks (>4 hours per day for ≥6 weeks); it includes cases of de novo acne and cases of pre-existing acne aggravated by wearing a mask. Maskne is characterized by acne lesions located on the facial area covered by the mask (Figure 6). It is caused by follicular occlusion; increased sebum secretion; mechanical stress (pressure, friction); and dysbiosis of the microbiome induced by changes in heat, pH, and humidity. Preventive measures include application of noncomedogenic moisturizers or gauze before wearing the mask as well as facial cleansing with appropriate nonalcoholic products. Similar to acne, rosacea often is aggravated by prolonged wearing of surgical masks (mask rosacea).^53,54

DERMATOSES REVEALED OR AGGRAVATED BY COVID-19

Exacerbation of various skin diseases has been reported after infection with SARS-CoV-2.⁵⁵ Psoriasis and acrodermatitis continua of Hallopeau,⁵⁶ which may progress into generalized, pustular, or erythrodermic forms,⁵⁷ have been reported; the role of hydroxychloroquine and oral corticosteroids used for the treatment of COVID-19 has been suspected.⁵⁷ Atopic dermatitis patients—26% to 43%—have experienced worsening of their disease after symptomatic COVID-19 infection.⁵⁸ The incidence of herpesvirus infections, including herpes zoster, increased during the pandemic.⁵⁹ Alopecia areata relapses occurred in 42.5% of 392 patients with preexisting disease within 2 months of COVID-19 onset in one study,⁶⁰ possibly favored by the psychological stress; however, some studies have not confirmed the aggravating role of COVID-19 on alopecia areata.⁶¹ Lupus erythematosus, which may relapse in the form of Rowell syndrome,⁶² and livedoid vasculopathy⁶³ also have been reported following COVID-19 infection.

SKIN MANIFESTATIONS ASSOCIATED WITH COVID-19 VACCINES

In parallel with the rapid spread of COVID-19 vaccination,⁴ an increasing number of skin manifestations has been observed following vaccination; these dermatoses now are more frequently reported than those related to natural SARS-CoV-2 infection.^64-70 Vaccine-induced skin manifestations have a reported incidence of approximately 4% and show a female predominance.⁶⁵ Most of them (79%) have been reported in association with messenger RNA (mRNA)–based vaccines, which have been the most widely used; however, the frequency of side effects would be lower after mRNA vaccines than after inactivated virus-based vaccines. Eighteen percent occurred after the adenoviral vector vaccine, and 3% after the inactivated virus vaccine.⁷⁰ Fifty-nine percent were observed after the first dose. They are clinically polymorphous and generally benign, regressing spontaneously after a few days, and they should not constitute a contraindication to vaccination.Interestingly, many skin manifestations are similar to those associated with natural SARS-CoV-2 infection; however, their frequency and severity does not seem to depend on whether the patients had developed skin reactions during prior SARS-CoV-2 infection. These reactions have been classified into several types:

• Immediate local reactions at the injection site: pain, erythema, or edema represent the vast majority (96%) of reactions to vaccines. They appear within 7 days after vaccination (average, 1 day), slightly more frequently (59%) after the first dose. They concern mostly young patients and are benign, regressing in 2 to 3 days.⁷⁰
 

• Delayed local reactions: characterized by pain or pruritus, erythema, and skin induration mimicking cellulitis (COVID arm) and represent 1.7% of postvaccination reactions. They correspond to a delayed hypersensitivity reaction and appear approximately 7 days after vaccination, most often after the first vaccine dose (75% of cases), which is almost invariably mRNA based.⁷⁰

• Urticarial reactions corresponding to an immediate (type 1) hypersensitivity reaction: constitute 1% of postvaccination reactions, probably due to an allergy to vaccine ingredients. They appear on average 1 day after vaccination, almost always with mRNA vaccines.⁷⁰

• Angioedema: characterized by mucosal or subcutaneous edema and constitutes 0.5% of postvaccination reactions. It is a potentially serious reaction that appears on average 12 hours after vaccination, always with an mRNA-based vaccine.⁷⁰

• Morbilliform rash: represents delayed hypersensitivity reactions (0.1% of postvaccination reactions) that appear mostly after the first dose (72%), on average 3 days after vaccination, always with an mRNA-based vaccine.⁷⁰

• Herpes zoster: usually develops after the first vaccine dose in elderly patients (69% of cases) on average 4 days after vaccination and constitutes 0.1% of postvaccination reactions.⁷¹

• Bullous diseases: mainly bullous pemphigoid (90%) and more rarely pemphigus (5%) or bullous erythema pigmentosum (5%). They appear in elderly patients on average 7 days after vaccination and constitute 0.04% of postvaccination reactions.⁷²

• Chilblainlike lesions: several such cases have been reported so far⁷³; they constitute 0.03% of postvaccination reactions.⁷⁰ Clinically, they are similar to those associated with natural COVID-19; they appear mostly after the first dose (64%), on average 5 days after vaccination with the mRNA or adenovirus vaccine, and show a female predominance. The appearance of these lesions in vaccinated patients, who are a priori not carriers of the virus, strongly suggests that CBLLs are due to the immune reaction against SARS-CoV-2 rather than to a direct effect of this virus on the skin, which also is a likely scenario with regards to other skin manifestations seen during the successive COVID-19 epidemic waves.^73-75

• Reactions to hyaluronic acid–containing cosmetic fillers: erythema, edema, and potentially painful induration at the filler injection sites. They constitute 0.04% of postvaccination skin reactions and appear 24 hours after vaccination with mRNA-based vaccines, equally after the first or second dose.⁷⁶

• Pityriasis rosea–like rash: most occur after the second dose of mRNA-based vaccines (0.023% of postvaccination skin reactions).⁷⁰

• Severe reactions: these include acute generalized exanthematous pustulosis⁷⁷ and Stevens-Johnson syndrome.⁷⁸ One case of each has been reported after the adenoviral vector vaccine 3 days after vaccination.

Other more rarely observed manifestations include reactivation/aggravation or de novo appearance of inflammatory dermatoses such as psoriasis,^79,80 leukocytoclastic vasculitis,^81,82 lymphocytic⁸³ or urticarial⁸⁴ vasculitis, Sweet syndrome,⁸⁵ lupus erythematosus, dermatomyositis,^86,87 alopecia,^37,88 infection with Trichophyton rubrum,⁸⁹ Grover disease,⁹⁰ and lymphomatoid reactions (such as recurrences of cutaneous T-cell lymphomas [CD30⁺], and de novo development of lymphomatoid papulosis).⁹¹

FINAL THOUGHTS

COVID-19 is associated with several skin manifestations, even though the causative role of SARS-CoV-2 has remained elusive. These dermatoses are highly polymorphous, mostly benign, and usually spontaneously regressive, but some of them reflect severe infection. They mostly were described during the first pandemic waves, reported in several national and international registries, which allowed for their morphological classification. Currently, cutaneous adverse effects of vaccines are the most frequently reported dermatoses associated with SARS-CoV-2, and it is likely that they will continue to be observed while COVID-19 vaccination lasts. Hopefully the end of the COVID-19 pandemic is near. In January 2023, the International Health Regulations Emergency Committee of the World Health Organization acknowledged that the COVID-19 pandemic may be approaching an inflexion point, and even though the event continues to constitute a public health emergency of international concern, the higher levels of population immunity achieved globally through infection and/or vaccination may limit the impact of SARS-CoV-2 on morbidity and mortality. However, there is little doubt that this virus will remain a permanently established pathogen in humans and animals for the foreseeable future.⁹² Therefore, physicians—especially dermatologists—should be aware of the various skin manifestations associated with COVID-19 so they can more efficiently manage their patients.

To the Editor:

Hailey-Hailey disease (HHD)(also known as familial benign chronic pemphigus) is an inherited autosomal-dominant condition in the family of chronic bullous diseases. It is characterized by flaccid blisters, erosions, and macerated vegetative plaques with a predilection for intertriginous sites. Lesions often are weeping, painful, pruritic, and malodorous, leading to decreased quality of life for patients. Complications of this chronic disease include an increased risk for secondary infection and malignant transformation to squamous cell carcinoma.¹

Treatment of HHD remains difficult. Topical steroids, oral steroids, and ablative techniques such as dermabrasion and ablative lasers are the most widely reported therapies. OnabotulinumtoxinA has been described as a successful treatment for patients with HHD, including for disease recalcitrant to other therapies.² We describe 2 patients with HHD who responded to treatment with intralesional onabotulinumtoxinA injections with and without adjuvant oral glycopyrrolate.

A 54-year-old woman presented with painful flaccid blisters under the breasts (Figure 1A) and in the axillae and groin of 3 weeks’ duration. Biopsy results from this initial visit were consistent with a diagnosis of HHD. The patient reported that the onset of blisters coincided with episodes of severe hyperhidrosis. Therapy with topical and oral steroids, antifungals, antibiotics, and topical aluminum chloride failed to achieve adequate disease control. After a discussion of the risks and benefits, the patient agreed to treatment with injections of onabotulinumtoxinA. At months 0, 3, and 6, the patient received 50 U of onabotulinumtoxinA under the breasts and in the axillae and the groin, for a total of 250 U each session. Each injection consisted of 2.5 U of onabotulinumtoxinA spaced 1-cm apart. Clinical improvement was noted within 2 weeks of initiating neuromodulator therapy. Follow-up at 9 months demonstrated improvement (Figure 1B); however, complete clearance was not achieved, and the patient required ongoing treatment with onabotulinumtoxinA every 3 months.

A 43-year-old woman presented with erythematous eroded plaques of the antecubital fossae, axillae, and chest (Figure 2A) of 10 years’ duration. A biopsy from an outside provider demonstrated findings consistent with a diagnosis of HHD. Prior therapies included topical and oral steroids. After a discussion of the risks and benefits, the patient was treated with onabotulinumtoxinA injections in combination with oral glycopyrrolate 5 mg daily. She received 30 U of onabotulinumtoxinA to each axilla, 10 U to each antecubital fossa, and 20 U to the central chest. At 1 month follow-up, the patient reported great improvement in lesion burden and active disease (Figure 2B). Nine months after treatment, her HHD was in complete remission with glycopyrrolate alone and she did not require further therapy with onabotulinumtoxinA.

Hailey-Hailey disease has been attributed to mutations of the ATPase secretory pathway Ca2+ transporting 1 gene, ATP2C1, that lead to aberrations in calcium signaling and subsequent impaired adhesion between keratinocytes.² These compromised cell-cell connections are worsened by the presence of humidity, causing further acantholysis. Chemical denervation of the sweat glands with botulinum toxin has been postulated to improve HHD by reducing moisture in vulnerable areas. Our 2 cases add to the existing literature documenting tangible clinical results that correlate with this hypothesis.^3-5

Our second case is unique in that the patient achieved rapid improvement using a combination of onabotulinumtoxinA and glycopyrrolate therapy. Both onabotulinumtoxinA and glycopyrrolate inhibit acetylcholine signaling that is required for sweat production; however, each drug exerts its effect on different zones of the cholinergic pathway, which may partially account for the synergistic effect of onabotulinumtoxinA and glycopyrrolate to improve HHD, as sweating is dually inhibited by the 2 drugs. Additionally, the combined local and systemic administration of these anticholinergic medications may further potentiate the sweat blockade, particularly in areas most prone to disease.

Botulinum toxin for the treatment of HHD is an effective monotherapy. The addition of an oral anticholinergic to local neuromodulator injections may speed symptom resolution and sustain disease remission. Further studies to evaluate this combination are warranted.

To the Editor:

Hailey-Hailey disease (HHD)(also known as familial benign chronic pemphigus) is an inherited autosomal-dominant condition in the family of chronic bullous diseases. It is characterized by flaccid blisters, erosions, and macerated vegetative plaques with a predilection for intertriginous sites. Lesions often are weeping, painful, pruritic, and malodorous, leading to decreased quality of life for patients. Complications of this chronic disease include an increased risk for secondary infection and malignant transformation to squamous cell carcinoma.¹

Treatment of HHD remains difficult. Topical steroids, oral steroids, and ablative techniques such as dermabrasion and ablative lasers are the most widely reported therapies. OnabotulinumtoxinA has been described as a successful treatment for patients with HHD, including for disease recalcitrant to other therapies.² We describe 2 patients with HHD who responded to treatment with intralesional onabotulinumtoxinA injections with and without adjuvant oral glycopyrrolate.

A 54-year-old woman presented with painful flaccid blisters under the breasts (Figure 1A) and in the axillae and groin of 3 weeks’ duration. Biopsy results from this initial visit were consistent with a diagnosis of HHD. The patient reported that the onset of blisters coincided with episodes of severe hyperhidrosis. Therapy with topical and oral steroids, antifungals, antibiotics, and topical aluminum chloride failed to achieve adequate disease control. After a discussion of the risks and benefits, the patient agreed to treatment with injections of onabotulinumtoxinA. At months 0, 3, and 6, the patient received 50 U of onabotulinumtoxinA under the breasts and in the axillae and the groin, for a total of 250 U each session. Each injection consisted of 2.5 U of onabotulinumtoxinA spaced 1-cm apart. Clinical improvement was noted within 2 weeks of initiating neuromodulator therapy. Follow-up at 9 months demonstrated improvement (Figure 1B); however, complete clearance was not achieved, and the patient required ongoing treatment with onabotulinumtoxinA every 3 months.

A 43-year-old woman presented with erythematous eroded plaques of the antecubital fossae, axillae, and chest (Figure 2A) of 10 years’ duration. A biopsy from an outside provider demonstrated findings consistent with a diagnosis of HHD. Prior therapies included topical and oral steroids. After a discussion of the risks and benefits, the patient was treated with onabotulinumtoxinA injections in combination with oral glycopyrrolate 5 mg daily. She received 30 U of onabotulinumtoxinA to each axilla, 10 U to each antecubital fossa, and 20 U to the central chest. At 1 month follow-up, the patient reported great improvement in lesion burden and active disease (Figure 2B). Nine months after treatment, her HHD was in complete remission with glycopyrrolate alone and she did not require further therapy with onabotulinumtoxinA.

Hailey-Hailey disease has been attributed to mutations of the ATPase secretory pathway Ca2+ transporting 1 gene, ATP2C1, that lead to aberrations in calcium signaling and subsequent impaired adhesion between keratinocytes.² These compromised cell-cell connections are worsened by the presence of humidity, causing further acantholysis. Chemical denervation of the sweat glands with botulinum toxin has been postulated to improve HHD by reducing moisture in vulnerable areas. Our 2 cases add to the existing literature documenting tangible clinical results that correlate with this hypothesis.^3-5

Our second case is unique in that the patient achieved rapid improvement using a combination of onabotulinumtoxinA and glycopyrrolate therapy. Both onabotulinumtoxinA and glycopyrrolate inhibit acetylcholine signaling that is required for sweat production; however, each drug exerts its effect on different zones of the cholinergic pathway, which may partially account for the synergistic effect of onabotulinumtoxinA and glycopyrrolate to improve HHD, as sweating is dually inhibited by the 2 drugs. Additionally, the combined local and systemic administration of these anticholinergic medications may further potentiate the sweat blockade, particularly in areas most prone to disease.

Botulinum toxin for the treatment of HHD is an effective monotherapy. The addition of an oral anticholinergic to local neuromodulator injections may speed symptom resolution and sustain disease remission. Further studies to evaluate this combination are warranted.

To the Editor:

Hailey-Hailey disease (HHD)(also known as familial benign chronic pemphigus) is an inherited autosomal-dominant condition in the family of chronic bullous diseases. It is characterized by flaccid blisters, erosions, and macerated vegetative plaques with a predilection for intertriginous sites. Lesions often are weeping, painful, pruritic, and malodorous, leading to decreased quality of life for patients. Complications of this chronic disease include an increased risk for secondary infection and malignant transformation to squamous cell carcinoma.¹

Treatment of HHD remains difficult. Topical steroids, oral steroids, and ablative techniques such as dermabrasion and ablative lasers are the most widely reported therapies. OnabotulinumtoxinA has been described as a successful treatment for patients with HHD, including for disease recalcitrant to other therapies.² We describe 2 patients with HHD who responded to treatment with intralesional onabotulinumtoxinA injections with and without adjuvant oral glycopyrrolate.

A 54-year-old woman presented with painful flaccid blisters under the breasts (Figure 1A) and in the axillae and groin of 3 weeks’ duration. Biopsy results from this initial visit were consistent with a diagnosis of HHD. The patient reported that the onset of blisters coincided with episodes of severe hyperhidrosis. Therapy with topical and oral steroids, antifungals, antibiotics, and topical aluminum chloride failed to achieve adequate disease control. After a discussion of the risks and benefits, the patient agreed to treatment with injections of onabotulinumtoxinA. At months 0, 3, and 6, the patient received 50 U of onabotulinumtoxinA under the breasts and in the axillae and the groin, for a total of 250 U each session. Each injection consisted of 2.5 U of onabotulinumtoxinA spaced 1-cm apart. Clinical improvement was noted within 2 weeks of initiating neuromodulator therapy. Follow-up at 9 months demonstrated improvement (Figure 1B); however, complete clearance was not achieved, and the patient required ongoing treatment with onabotulinumtoxinA every 3 months.

A 43-year-old woman presented with erythematous eroded plaques of the antecubital fossae, axillae, and chest (Figure 2A) of 10 years’ duration. A biopsy from an outside provider demonstrated findings consistent with a diagnosis of HHD. Prior therapies included topical and oral steroids. After a discussion of the risks and benefits, the patient was treated with onabotulinumtoxinA injections in combination with oral glycopyrrolate 5 mg daily. She received 30 U of onabotulinumtoxinA to each axilla, 10 U to each antecubital fossa, and 20 U to the central chest. At 1 month follow-up, the patient reported great improvement in lesion burden and active disease (Figure 2B). Nine months after treatment, her HHD was in complete remission with glycopyrrolate alone and she did not require further therapy with onabotulinumtoxinA.

Hailey-Hailey disease has been attributed to mutations of the ATPase secretory pathway Ca2+ transporting 1 gene, ATP2C1, that lead to aberrations in calcium signaling and subsequent impaired adhesion between keratinocytes.² These compromised cell-cell connections are worsened by the presence of humidity, causing further acantholysis. Chemical denervation of the sweat glands with botulinum toxin has been postulated to improve HHD by reducing moisture in vulnerable areas. Our 2 cases add to the existing literature documenting tangible clinical results that correlate with this hypothesis.^3-5

Our second case is unique in that the patient achieved rapid improvement using a combination of onabotulinumtoxinA and glycopyrrolate therapy. Both onabotulinumtoxinA and glycopyrrolate inhibit acetylcholine signaling that is required for sweat production; however, each drug exerts its effect on different zones of the cholinergic pathway, which may partially account for the synergistic effect of onabotulinumtoxinA and glycopyrrolate to improve HHD, as sweating is dually inhibited by the 2 drugs. Additionally, the combined local and systemic administration of these anticholinergic medications may further potentiate the sweat blockade, particularly in areas most prone to disease.

Botulinum toxin for the treatment of HHD is an effective monotherapy. The addition of an oral anticholinergic to local neuromodulator injections may speed symptom resolution and sustain disease remission. Further studies to evaluate this combination are warranted.

The Diagnosis: Cutaneous Furuncular Myiasis

Histopathology of the punch biopsy showed an undulating chitinous exoskeleton and pigmented spines (setae) protruding from the exoskeleton with associated superficial perivascular lymphohistiocytic infiltrates on hematoxylin and eosin stain (Figure 1). Live insect larvae were observed and extracted, which immediately relieved the crawling sensation (Figure 2). Light microscopy of the larva showed a row of hooks surrounding a tapered body with a head attached anteriorly (Figure 3).

Myiasis is a parasitic infestation of the dipterous fly’s larvae in the host organ and tissue. There are 5 types of myiasis based on the location of the infestation: wound myiasis occurs with egg infestations on an open wound; furuncular myiasis results from egg placement by penetration of healthy skin by a mosquito vector; plaque myiasis comprises the placement of eggs on clothing through several maggots and flies; creeping myiasis involves the Gasterophilus fly delivering the larva intradermally; and body cavity myiasis may develop in the orbit, nasal cavity, urogenital system, and gastrointestinal tract.^1-3

Furuncular myiasis infestation occurs via a complex life cycle in which mosquitoes act as a vector and transfer the eggs to the human or animal host.^1-3 Botfly larvae then penetrate the skin and reside within the subdermis to mature. Adults then emerge after 1 month to repeat the cycle.¹Dermatobia hominis and Cordylobia anthropophaga are the most common causes of furuncular myiasis.^2,3 Furuncular myiasis commonly presents in travelers that are returning from tropical countries. Initially, an itching erythematous papule develops. After the larvae mature, they can appear as boil-like lesions with a small central punctum.^1-3 Dermoscopy can be utilized for visualization of different larvae anatomy such as a furuncularlike lesion, spines, and posterior breathing spiracle from the central punctum.⁴

Our patient’s recent travel to the Amazon in Brazil, clinical history, and histopathologic findings ruled out other differential diagnoses such as cutaneous larva migrans, gnathostomiasis, loiasis, and tungiasis.

Treatment is curative with the extraction of the intact larva from the nodule. Localized skin anesthetic injection can be used to bulge the larva outward for easier extraction. A single dose of ivermectin 15 mg can treat the parasitic infestation of myiasis.^1-3

The Diagnosis: Cutaneous Furuncular Myiasis

Histopathology of the punch biopsy showed an undulating chitinous exoskeleton and pigmented spines (setae) protruding from the exoskeleton with associated superficial perivascular lymphohistiocytic infiltrates on hematoxylin and eosin stain (Figure 1). Live insect larvae were observed and extracted, which immediately relieved the crawling sensation (Figure 2). Light microscopy of the larva showed a row of hooks surrounding a tapered body with a head attached anteriorly (Figure 3).

Myiasis is a parasitic infestation of the dipterous fly’s larvae in the host organ and tissue. There are 5 types of myiasis based on the location of the infestation: wound myiasis occurs with egg infestations on an open wound; furuncular myiasis results from egg placement by penetration of healthy skin by a mosquito vector; plaque myiasis comprises the placement of eggs on clothing through several maggots and flies; creeping myiasis involves the Gasterophilus fly delivering the larva intradermally; and body cavity myiasis may develop in the orbit, nasal cavity, urogenital system, and gastrointestinal tract.^1-3

Furuncular myiasis infestation occurs via a complex life cycle in which mosquitoes act as a vector and transfer the eggs to the human or animal host.^1-3 Botfly larvae then penetrate the skin and reside within the subdermis to mature. Adults then emerge after 1 month to repeat the cycle.¹Dermatobia hominis and Cordylobia anthropophaga are the most common causes of furuncular myiasis.^2,3 Furuncular myiasis commonly presents in travelers that are returning from tropical countries. Initially, an itching erythematous papule develops. After the larvae mature, they can appear as boil-like lesions with a small central punctum.^1-3 Dermoscopy can be utilized for visualization of different larvae anatomy such as a furuncularlike lesion, spines, and posterior breathing spiracle from the central punctum.⁴

Our patient’s recent travel to the Amazon in Brazil, clinical history, and histopathologic findings ruled out other differential diagnoses such as cutaneous larva migrans, gnathostomiasis, loiasis, and tungiasis.

Treatment is curative with the extraction of the intact larva from the nodule. Localized skin anesthetic injection can be used to bulge the larva outward for easier extraction. A single dose of ivermectin 15 mg can treat the parasitic infestation of myiasis.^1-3

The Diagnosis: Cutaneous Furuncular Myiasis

Histopathology of the punch biopsy showed an undulating chitinous exoskeleton and pigmented spines (setae) protruding from the exoskeleton with associated superficial perivascular lymphohistiocytic infiltrates on hematoxylin and eosin stain (Figure 1). Live insect larvae were observed and extracted, which immediately relieved the crawling sensation (Figure 2). Light microscopy of the larva showed a row of hooks surrounding a tapered body with a head attached anteriorly (Figure 3).

Myiasis is a parasitic infestation of the dipterous fly’s larvae in the host organ and tissue. There are 5 types of myiasis based on the location of the infestation: wound myiasis occurs with egg infestations on an open wound; furuncular myiasis results from egg placement by penetration of healthy skin by a mosquito vector; plaque myiasis comprises the placement of eggs on clothing through several maggots and flies; creeping myiasis involves the Gasterophilus fly delivering the larva intradermally; and body cavity myiasis may develop in the orbit, nasal cavity, urogenital system, and gastrointestinal tract.^1-3

Furuncular myiasis infestation occurs via a complex life cycle in which mosquitoes act as a vector and transfer the eggs to the human or animal host.^1-3 Botfly larvae then penetrate the skin and reside within the subdermis to mature. Adults then emerge after 1 month to repeat the cycle.¹Dermatobia hominis and Cordylobia anthropophaga are the most common causes of furuncular myiasis.^2,3 Furuncular myiasis commonly presents in travelers that are returning from tropical countries. Initially, an itching erythematous papule develops. After the larvae mature, they can appear as boil-like lesions with a small central punctum.^1-3 Dermoscopy can be utilized for visualization of different larvae anatomy such as a furuncularlike lesion, spines, and posterior breathing spiracle from the central punctum.⁴

Our patient’s recent travel to the Amazon in Brazil, clinical history, and histopathologic findings ruled out other differential diagnoses such as cutaneous larva migrans, gnathostomiasis, loiasis, and tungiasis.

Treatment is curative with the extraction of the intact larva from the nodule. Localized skin anesthetic injection can be used to bulge the larva outward for easier extraction. A single dose of ivermectin 15 mg can treat the parasitic infestation of myiasis.^1-3

To the Editor:

Vitiligolike depigmentation has been known to develop around the sites of origin of melanoma or more rarely in patients treated with antimelanoma therapy.¹ Vitiligo is characterized by white patchy depigmentation of the skin caused by the loss of functional melanocytes from the epidermis. The exact mechanisms of disease are unknown and multifactorial; however, autoimmunity plays a central role. Interferon gamma (IFN-γ), C-X-C chemokine ligand 10, and IL-22 have been identified as key mediators in an inflammatory cascade leading to the stimulation of the innate immune response against melanocyte antigens.^2,3 Research suggests melanoma-associated vitiligolike leukoderma also results from an immune reaction directed against antigenic determinants shared by both normal and malignant melanocytes.³ Vitiligolike lesions have been associated with the use of immunomodulatory agents such as nivolumab, a fully humanized monoclonal IgG4 antibody, which blocks the programmed cell death protein 1 (PD-1) receptor that normally is expressed on T cells during the effector phase of T-cell activation.^4,5 In the tumor microenvironment, the PD-1 receptor is stimulated, leading to downregulation of the T-cell effector function and destruction of T cells.⁵ Due to T-cell apoptosis and consequent suppression of the immune response, tumorigenesis continues. By inhibiting the PD-1 receptor, nivolumab increases the number of active T cells and antitumor response. However, the distressing side effect of vitiligolike depigmentation has been reported in 15% to 25% of treated patients.⁶

In a meta-analysis by Teulings et al,⁷ patients with new-onset vitiligo and malignant melanoma demonstrated a 2-fold decrease in cancer progression and a 4-fold decreased risk for death vs patients without vitiligo development. Thus, in patients with melanoma, vitiligolike depigmentation should be considered a good prognostic indicator as well as a visible sign of spontaneous or therapy-induced antihumoral immune response against melanocyte differentiation antigens, as it is associated with a notable survival benefit in patients receiving immunotherapy for metastatic melanoma.³ We describe a case of diffuse vitiligolike depigmentation that developed suddenly during nivolumab treatment, causing much distress to the patient.

A 75-year-old woman presented to the clinic with a chief concern of sudden diffuse skin discoloration primarily affecting the face, hands, and extremities of 3 weeks’ duration. She had a medical history of metastatic melanoma—the site of the primary melanoma was never identified—and she was undergoing immune-modulating therapy with nivolumab. She was on her fifth month of treatment and was experiencing a robust therapeutic response with a reported 100% clearance of the metastatic melanoma as observed on a positron emission tomography scan. The patchy depigmentation of skin was causing her much distress. Physical examination revealed diffuse patches of hypopigmentation on the trunk, face, and extremities (Figure). Shave biopsies of the right lateral arm demonstrated changes consistent with vitiligo, with an adjacent biopsy illustrating normal skin characteristics. Triamcinolone ointment 0.1% was initiated, with instruction to apply it to affected areas twice daily for 2 weeks. However, there was no improvement, and she discontinued use.

At 3-month follow-up, the depigmentation persisted, prompting a trial of hydroquinone cream 4% to be used sparingly in cosmetically sensitive areas such as the face and dorsal aspects of the hands. Additionally, diligent photoprotection was advised. Upon re-evaluation 9 months later, the patient remained in cancer remission, continued nivolumab therapy, and reported improvement in the hypopigmentation with a more even skin color with topical hydroquinone use. She no longer noticed starkly contrasting hypopigmented patches.

Vitiligo is a benign skin condition characterized by white depigmented macules and patches. The key feature of the disorder is loss of functional melanocytes from the cutaneous epidermis and sometimes from the hair follicles, with various theories on the cause. It has been suggested that the disease is multifactorial, involving both genetics and environmental factors.² Regardless of the exact mechanism, the result is always the same: loss of melanin pigment in cells due to loss of melanocytes.

Autoimmunity plays a central role in the causation of vitiligo and was first suspected as a possible cause due to the association of vitiligo with several other autoimmune disorders, such as thyroiditis.⁸ An epidemiological survey from the United Kingdom and North America (N=2624) found that 19.4% of vitiligo patients aged 20 years or older also reported a clinical history of autoimmune thyroid disease compared with 2.4% of the overall White population of the same age.⁹ Interferon gamma, C-X-C chemokine ligand 10, and IL-22 receptors stimulate the innate immune response, resulting in an overactive danger signaling cascade, which leads to proinflammatory signals against melanocyte antigens.^2,3 The adaptive immune system also participates in the progression of vitiligo by activating dermal dendritic cells to attack melanocytes along with melanocyte-specific cytotoxic T cells.

Immunomodulatory agents utilized in the treatment of metastatic melanoma have been linked to vitiligolike depigmentation. In those receiving PD-1 immunotherapy for metastatic melanoma, vitiligolike lesions have been reported in 15% to 25% of patients.⁶ Typically, the PD-1 molecule has a regulatory function on effector T cells. Interaction of the PD-1 receptor with its ligands occurs primarily in peripheral tissue causing apoptosis and downregulation of effector T cells with the goal of decreasing collateral damage to surrounding tissues by active T cells.⁵ In the tumor microenvironment, however, suppression of the host’s immune response is enhanced by aberrant stimulation of the PD-1 receptor, causing downregulation of the T-cell effector function, T-cell destruction, and apoptosis, which results in continued tumor growth. Nivolumab, a fully humanized monoclonal IgG4 antibody, selectively inhibits the PD-1 receptor, disrupting the regulator pathway that would typically end in T-cell destruction.⁵ Accordingly, the population of active T cells is increased along with the antitumor response.^4,10 Nivolumab exhibits success as an immunotherapeutic agent, with an overall survival rate in patients with metastatic melanoma undergoing nivolumab therapy of 41% to 42% at 3 years and 35% at 5 years.¹¹ However, therapeutic manipulation of the host’s immune response does not come without a cost. Vitiligolike lesions have been reported in up to a quarter of patients receiving PD-1 immunotherapy for metastatic melanoma.⁶

The relationship between vitiligolike depigmentation and melanoma can be explained by the immune activation against antigens associated with melanoma that also are expressed by normal melanocytes. In clinical observations of patients with melanoma and patients with vitiligo, antibodies to human melanocyte antigens were present in 80% (24/30) of patients vs 7% (2/28) in the control group.¹² The autoimmune response results from a cross-reaction of melanoma cells that share the same antigens as normal melanocytes, such as melanoma antigen recognized by T cells 1 (MART-1), gp100, and tyrosinase.^13,14

Development of vitiligolike depigmentation in patients with metastatic melanoma treated with nivolumab has been reported to occur between 2 and 15 months after the start of PD-1 therapy. This side effect of treatment correlates with favorable clinical outcomes.^15,16 Enhancing immune recognition of melanocytes in patients with melanoma confers a survival advantage, as studies by Koh et al¹⁷ and Norlund et al¹⁸ involving patients who developed vitiligolike hypopigmentation associated with malignant melanoma indicated a better prognosis than for those without hypopigmentation. The 5-year survival rate of patients with both malignant melanoma and vitiligo was reported as 60% to 67% when it was estimated that only 30% to 50% of patients should have survived that duration of time.^17,18 Similarly, a systematic review of patients with melanoma stages III and IV reported that those with associated hypopigmentation had a 2- to 4-fold decreased risk of disease progression and death compared to patients without depigmentation.⁷

Use of traditional treatment therapies for vitiligo is based on the ability of the therapy to suppress the immune system. However, in patients with metastatic melanoma undergoing immune-modulating cancer therapies, traditional treatment options may counter the antitumor effects of the targeted immunotherapies and should be used with caution. Our patient displayed improvement in the appearance of her starkly contrasting hypopigmented patches with the use of hydroquinone cream 4%, which induced necrotic death of melanocytes by inhibiting the conversion of L-3,4-dihydroxyphenylalanine to melanin by tyrosinase.¹⁹ The effect achieved by using topical hydroquinone 4% was a lighter skin appearance in areas of application.

There is no cure for vitiligo, and although it is a benign condition, it can negatively impact a patient's quality of life. In some countries, vitiligo is confused with leprosy, resulting in a social stigma attached to the diagnosis. Many patients are frightened or embarrassed by the diagnosis of vitiligo and its effects, and they often experience discrimination.² Patients with vitiligo also experience more psychological difficulties such as depression.²⁰ The unpredictability of vitiligo is associated with negative emotions including fear of spreading the lesions, shame, insecurity, and sadness.²¹ Supportive care measures, including psychological support and counseling, are recommended. Additionally, upon initiation of anti–PD-1 therapies, expectations should be discussed with patients concerning the possibilities of depigmentation and associated treatment results. Although the occurrence of vitiligo may cause the patient concern, it should be communicated that its presence is a positive indicator of a vigorous antimelanoma immunity and an increased survival rate.⁷

Vitiligolike depigmentation is a known rare adverse effect of nivolumab treatment. Although aesthetically unfavorable for the patient, the development of vitiligolike lesions while undergoing immunotherapy for melanoma may be a sign of a promising clinical outcome due to an effective immune response to melanoma antigens. Our patient remains in remission without any evidence of melanoma after 9 months of therapy, which offers support for a promising outcome for melanoma patients who experience vitiligolike depigmentation.

To the Editor:

Vitiligolike depigmentation has been known to develop around the sites of origin of melanoma or more rarely in patients treated with antimelanoma therapy.¹ Vitiligo is characterized by white patchy depigmentation of the skin caused by the loss of functional melanocytes from the epidermis. The exact mechanisms of disease are unknown and multifactorial; however, autoimmunity plays a central role. Interferon gamma (IFN-γ), C-X-C chemokine ligand 10, and IL-22 have been identified as key mediators in an inflammatory cascade leading to the stimulation of the innate immune response against melanocyte antigens.^2,3 Research suggests melanoma-associated vitiligolike leukoderma also results from an immune reaction directed against antigenic determinants shared by both normal and malignant melanocytes.³ Vitiligolike lesions have been associated with the use of immunomodulatory agents such as nivolumab, a fully humanized monoclonal IgG4 antibody, which blocks the programmed cell death protein 1 (PD-1) receptor that normally is expressed on T cells during the effector phase of T-cell activation.^4,5 In the tumor microenvironment, the PD-1 receptor is stimulated, leading to downregulation of the T-cell effector function and destruction of T cells.⁵ Due to T-cell apoptosis and consequent suppression of the immune response, tumorigenesis continues. By inhibiting the PD-1 receptor, nivolumab increases the number of active T cells and antitumor response. However, the distressing side effect of vitiligolike depigmentation has been reported in 15% to 25% of treated patients.⁶

In a meta-analysis by Teulings et al,⁷ patients with new-onset vitiligo and malignant melanoma demonstrated a 2-fold decrease in cancer progression and a 4-fold decreased risk for death vs patients without vitiligo development. Thus, in patients with melanoma, vitiligolike depigmentation should be considered a good prognostic indicator as well as a visible sign of spontaneous or therapy-induced antihumoral immune response against melanocyte differentiation antigens, as it is associated with a notable survival benefit in patients receiving immunotherapy for metastatic melanoma.³ We describe a case of diffuse vitiligolike depigmentation that developed suddenly during nivolumab treatment, causing much distress to the patient.

A 75-year-old woman presented to the clinic with a chief concern of sudden diffuse skin discoloration primarily affecting the face, hands, and extremities of 3 weeks’ duration. She had a medical history of metastatic melanoma—the site of the primary melanoma was never identified—and she was undergoing immune-modulating therapy with nivolumab. She was on her fifth month of treatment and was experiencing a robust therapeutic response with a reported 100% clearance of the metastatic melanoma as observed on a positron emission tomography scan. The patchy depigmentation of skin was causing her much distress. Physical examination revealed diffuse patches of hypopigmentation on the trunk, face, and extremities (Figure). Shave biopsies of the right lateral arm demonstrated changes consistent with vitiligo, with an adjacent biopsy illustrating normal skin characteristics. Triamcinolone ointment 0.1% was initiated, with instruction to apply it to affected areas twice daily for 2 weeks. However, there was no improvement, and she discontinued use.

At 3-month follow-up, the depigmentation persisted, prompting a trial of hydroquinone cream 4% to be used sparingly in cosmetically sensitive areas such as the face and dorsal aspects of the hands. Additionally, diligent photoprotection was advised. Upon re-evaluation 9 months later, the patient remained in cancer remission, continued nivolumab therapy, and reported improvement in the hypopigmentation with a more even skin color with topical hydroquinone use. She no longer noticed starkly contrasting hypopigmented patches.

Vitiligo is a benign skin condition characterized by white depigmented macules and patches. The key feature of the disorder is loss of functional melanocytes from the cutaneous epidermis and sometimes from the hair follicles, with various theories on the cause. It has been suggested that the disease is multifactorial, involving both genetics and environmental factors.² Regardless of the exact mechanism, the result is always the same: loss of melanin pigment in cells due to loss of melanocytes.

Autoimmunity plays a central role in the causation of vitiligo and was first suspected as a possible cause due to the association of vitiligo with several other autoimmune disorders, such as thyroiditis.⁸ An epidemiological survey from the United Kingdom and North America (N=2624) found that 19.4% of vitiligo patients aged 20 years or older also reported a clinical history of autoimmune thyroid disease compared with 2.4% of the overall White population of the same age.⁹ Interferon gamma, C-X-C chemokine ligand 10, and IL-22 receptors stimulate the innate immune response, resulting in an overactive danger signaling cascade, which leads to proinflammatory signals against melanocyte antigens.^2,3 The adaptive immune system also participates in the progression of vitiligo by activating dermal dendritic cells to attack melanocytes along with melanocyte-specific cytotoxic T cells.

Immunomodulatory agents utilized in the treatment of metastatic melanoma have been linked to vitiligolike depigmentation. In those receiving PD-1 immunotherapy for metastatic melanoma, vitiligolike lesions have been reported in 15% to 25% of patients.⁶ Typically, the PD-1 molecule has a regulatory function on effector T cells. Interaction of the PD-1 receptor with its ligands occurs primarily in peripheral tissue causing apoptosis and downregulation of effector T cells with the goal of decreasing collateral damage to surrounding tissues by active T cells.⁵ In the tumor microenvironment, however, suppression of the host’s immune response is enhanced by aberrant stimulation of the PD-1 receptor, causing downregulation of the T-cell effector function, T-cell destruction, and apoptosis, which results in continued tumor growth. Nivolumab, a fully humanized monoclonal IgG4 antibody, selectively inhibits the PD-1 receptor, disrupting the regulator pathway that would typically end in T-cell destruction.⁵ Accordingly, the population of active T cells is increased along with the antitumor response.^4,10 Nivolumab exhibits success as an immunotherapeutic agent, with an overall survival rate in patients with metastatic melanoma undergoing nivolumab therapy of 41% to 42% at 3 years and 35% at 5 years.¹¹ However, therapeutic manipulation of the host’s immune response does not come without a cost. Vitiligolike lesions have been reported in up to a quarter of patients receiving PD-1 immunotherapy for metastatic melanoma.⁶

The relationship between vitiligolike depigmentation and melanoma can be explained by the immune activation against antigens associated with melanoma that also are expressed by normal melanocytes. In clinical observations of patients with melanoma and patients with vitiligo, antibodies to human melanocyte antigens were present in 80% (24/30) of patients vs 7% (2/28) in the control group.¹² The autoimmune response results from a cross-reaction of melanoma cells that share the same antigens as normal melanocytes, such as melanoma antigen recognized by T cells 1 (MART-1), gp100, and tyrosinase.^13,14

Development of vitiligolike depigmentation in patients with metastatic melanoma treated with nivolumab has been reported to occur between 2 and 15 months after the start of PD-1 therapy. This side effect of treatment correlates with favorable clinical outcomes.^15,16 Enhancing immune recognition of melanocytes in patients with melanoma confers a survival advantage, as studies by Koh et al¹⁷ and Norlund et al¹⁸ involving patients who developed vitiligolike hypopigmentation associated with malignant melanoma indicated a better prognosis than for those without hypopigmentation. The 5-year survival rate of patients with both malignant melanoma and vitiligo was reported as 60% to 67% when it was estimated that only 30% to 50% of patients should have survived that duration of time.^17,18 Similarly, a systematic review of patients with melanoma stages III and IV reported that those with associated hypopigmentation had a 2- to 4-fold decreased risk of disease progression and death compared to patients without depigmentation.⁷

Use of traditional treatment therapies for vitiligo is based on the ability of the therapy to suppress the immune system. However, in patients with metastatic melanoma undergoing immune-modulating cancer therapies, traditional treatment options may counter the antitumor effects of the targeted immunotherapies and should be used with caution. Our patient displayed improvement in the appearance of her starkly contrasting hypopigmented patches with the use of hydroquinone cream 4%, which induced necrotic death of melanocytes by inhibiting the conversion of L-3,4-dihydroxyphenylalanine to melanin by tyrosinase.¹⁹ The effect achieved by using topical hydroquinone 4% was a lighter skin appearance in areas of application.

There is no cure for vitiligo, and although it is a benign condition, it can negatively impact a patient's quality of life. In some countries, vitiligo is confused with leprosy, resulting in a social stigma attached to the diagnosis. Many patients are frightened or embarrassed by the diagnosis of vitiligo and its effects, and they often experience discrimination.² Patients with vitiligo also experience more psychological difficulties such as depression.²⁰ The unpredictability of vitiligo is associated with negative emotions including fear of spreading the lesions, shame, insecurity, and sadness.²¹ Supportive care measures, including psychological support and counseling, are recommended. Additionally, upon initiation of anti–PD-1 therapies, expectations should be discussed with patients concerning the possibilities of depigmentation and associated treatment results. Although the occurrence of vitiligo may cause the patient concern, it should be communicated that its presence is a positive indicator of a vigorous antimelanoma immunity and an increased survival rate.⁷

Vitiligolike depigmentation is a known rare adverse effect of nivolumab treatment. Although aesthetically unfavorable for the patient, the development of vitiligolike lesions while undergoing immunotherapy for melanoma may be a sign of a promising clinical outcome due to an effective immune response to melanoma antigens. Our patient remains in remission without any evidence of melanoma after 9 months of therapy, which offers support for a promising outcome for melanoma patients who experience vitiligolike depigmentation.

To the Editor:

Vitiligolike depigmentation has been known to develop around the sites of origin of melanoma or more rarely in patients treated with antimelanoma therapy.¹ Vitiligo is characterized by white patchy depigmentation of the skin caused by the loss of functional melanocytes from the epidermis. The exact mechanisms of disease are unknown and multifactorial; however, autoimmunity plays a central role. Interferon gamma (IFN-γ), C-X-C chemokine ligand 10, and IL-22 have been identified as key mediators in an inflammatory cascade leading to the stimulation of the innate immune response against melanocyte antigens.^2,3 Research suggests melanoma-associated vitiligolike leukoderma also results from an immune reaction directed against antigenic determinants shared by both normal and malignant melanocytes.³ Vitiligolike lesions have been associated with the use of immunomodulatory agents such as nivolumab, a fully humanized monoclonal IgG4 antibody, which blocks the programmed cell death protein 1 (PD-1) receptor that normally is expressed on T cells during the effector phase of T-cell activation.^4,5 In the tumor microenvironment, the PD-1 receptor is stimulated, leading to downregulation of the T-cell effector function and destruction of T cells.⁵ Due to T-cell apoptosis and consequent suppression of the immune response, tumorigenesis continues. By inhibiting the PD-1 receptor, nivolumab increases the number of active T cells and antitumor response. However, the distressing side effect of vitiligolike depigmentation has been reported in 15% to 25% of treated patients.⁶

In a meta-analysis by Teulings et al,⁷ patients with new-onset vitiligo and malignant melanoma demonstrated a 2-fold decrease in cancer progression and a 4-fold decreased risk for death vs patients without vitiligo development. Thus, in patients with melanoma, vitiligolike depigmentation should be considered a good prognostic indicator as well as a visible sign of spontaneous or therapy-induced antihumoral immune response against melanocyte differentiation antigens, as it is associated with a notable survival benefit in patients receiving immunotherapy for metastatic melanoma.³ We describe a case of diffuse vitiligolike depigmentation that developed suddenly during nivolumab treatment, causing much distress to the patient.

A 75-year-old woman presented to the clinic with a chief concern of sudden diffuse skin discoloration primarily affecting the face, hands, and extremities of 3 weeks’ duration. She had a medical history of metastatic melanoma—the site of the primary melanoma was never identified—and she was undergoing immune-modulating therapy with nivolumab. She was on her fifth month of treatment and was experiencing a robust therapeutic response with a reported 100% clearance of the metastatic melanoma as observed on a positron emission tomography scan. The patchy depigmentation of skin was causing her much distress. Physical examination revealed diffuse patches of hypopigmentation on the trunk, face, and extremities (Figure). Shave biopsies of the right lateral arm demonstrated changes consistent with vitiligo, with an adjacent biopsy illustrating normal skin characteristics. Triamcinolone ointment 0.1% was initiated, with instruction to apply it to affected areas twice daily for 2 weeks. However, there was no improvement, and she discontinued use.

At 3-month follow-up, the depigmentation persisted, prompting a trial of hydroquinone cream 4% to be used sparingly in cosmetically sensitive areas such as the face and dorsal aspects of the hands. Additionally, diligent photoprotection was advised. Upon re-evaluation 9 months later, the patient remained in cancer remission, continued nivolumab therapy, and reported improvement in the hypopigmentation with a more even skin color with topical hydroquinone use. She no longer noticed starkly contrasting hypopigmented patches.

Vitiligo is a benign skin condition characterized by white depigmented macules and patches. The key feature of the disorder is loss of functional melanocytes from the cutaneous epidermis and sometimes from the hair follicles, with various theories on the cause. It has been suggested that the disease is multifactorial, involving both genetics and environmental factors.² Regardless of the exact mechanism, the result is always the same: loss of melanin pigment in cells due to loss of melanocytes.

Autoimmunity plays a central role in the causation of vitiligo and was first suspected as a possible cause due to the association of vitiligo with several other autoimmune disorders, such as thyroiditis.⁸ An epidemiological survey from the United Kingdom and North America (N=2624) found that 19.4% of vitiligo patients aged 20 years or older also reported a clinical history of autoimmune thyroid disease compared with 2.4% of the overall White population of the same age.⁹ Interferon gamma, C-X-C chemokine ligand 10, and IL-22 receptors stimulate the innate immune response, resulting in an overactive danger signaling cascade, which leads to proinflammatory signals against melanocyte antigens.^2,3 The adaptive immune system also participates in the progression of vitiligo by activating dermal dendritic cells to attack melanocytes along with melanocyte-specific cytotoxic T cells.

Immunomodulatory agents utilized in the treatment of metastatic melanoma have been linked to vitiligolike depigmentation. In those receiving PD-1 immunotherapy for metastatic melanoma, vitiligolike lesions have been reported in 15% to 25% of patients.⁶ Typically, the PD-1 molecule has a regulatory function on effector T cells. Interaction of the PD-1 receptor with its ligands occurs primarily in peripheral tissue causing apoptosis and downregulation of effector T cells with the goal of decreasing collateral damage to surrounding tissues by active T cells.⁵ In the tumor microenvironment, however, suppression of the host’s immune response is enhanced by aberrant stimulation of the PD-1 receptor, causing downregulation of the T-cell effector function, T-cell destruction, and apoptosis, which results in continued tumor growth. Nivolumab, a fully humanized monoclonal IgG4 antibody, selectively inhibits the PD-1 receptor, disrupting the regulator pathway that would typically end in T-cell destruction.⁵ Accordingly, the population of active T cells is increased along with the antitumor response.^4,10 Nivolumab exhibits success as an immunotherapeutic agent, with an overall survival rate in patients with metastatic melanoma undergoing nivolumab therapy of 41% to 42% at 3 years and 35% at 5 years.¹¹ However, therapeutic manipulation of the host’s immune response does not come without a cost. Vitiligolike lesions have been reported in up to a quarter of patients receiving PD-1 immunotherapy for metastatic melanoma.⁶

The relationship between vitiligolike depigmentation and melanoma can be explained by the immune activation against antigens associated with melanoma that also are expressed by normal melanocytes. In clinical observations of patients with melanoma and patients with vitiligo, antibodies to human melanocyte antigens were present in 80% (24/30) of patients vs 7% (2/28) in the control group.¹² The autoimmune response results from a cross-reaction of melanoma cells that share the same antigens as normal melanocytes, such as melanoma antigen recognized by T cells 1 (MART-1), gp100, and tyrosinase.^13,14

Development of vitiligolike depigmentation in patients with metastatic melanoma treated with nivolumab has been reported to occur between 2 and 15 months after the start of PD-1 therapy. This side effect of treatment correlates with favorable clinical outcomes.^15,16 Enhancing immune recognition of melanocytes in patients with melanoma confers a survival advantage, as studies by Koh et al¹⁷ and Norlund et al¹⁸ involving patients who developed vitiligolike hypopigmentation associated with malignant melanoma indicated a better prognosis than for those without hypopigmentation. The 5-year survival rate of patients with both malignant melanoma and vitiligo was reported as 60% to 67% when it was estimated that only 30% to 50% of patients should have survived that duration of time.^17,18 Similarly, a systematic review of patients with melanoma stages III and IV reported that those with associated hypopigmentation had a 2- to 4-fold decreased risk of disease progression and death compared to patients without depigmentation.⁷

Use of traditional treatment therapies for vitiligo is based on the ability of the therapy to suppress the immune system. However, in patients with metastatic melanoma undergoing immune-modulating cancer therapies, traditional treatment options may counter the antitumor effects of the targeted immunotherapies and should be used with caution. Our patient displayed improvement in the appearance of her starkly contrasting hypopigmented patches with the use of hydroquinone cream 4%, which induced necrotic death of melanocytes by inhibiting the conversion of L-3,4-dihydroxyphenylalanine to melanin by tyrosinase.¹⁹ The effect achieved by using topical hydroquinone 4% was a lighter skin appearance in areas of application.

There is no cure for vitiligo, and although it is a benign condition, it can negatively impact a patient's quality of life. In some countries, vitiligo is confused with leprosy, resulting in a social stigma attached to the diagnosis. Many patients are frightened or embarrassed by the diagnosis of vitiligo and its effects, and they often experience discrimination.² Patients with vitiligo also experience more psychological difficulties such as depression.²⁰ The unpredictability of vitiligo is associated with negative emotions including fear of spreading the lesions, shame, insecurity, and sadness.²¹ Supportive care measures, including psychological support and counseling, are recommended. Additionally, upon initiation of anti–PD-1 therapies, expectations should be discussed with patients concerning the possibilities of depigmentation and associated treatment results. Although the occurrence of vitiligo may cause the patient concern, it should be communicated that its presence is a positive indicator of a vigorous antimelanoma immunity and an increased survival rate.⁷

Vitiligolike depigmentation is a known rare adverse effect of nivolumab treatment. Although aesthetically unfavorable for the patient, the development of vitiligolike lesions while undergoing immunotherapy for melanoma may be a sign of a promising clinical outcome due to an effective immune response to melanoma antigens. Our patient remains in remission without any evidence of melanoma after 9 months of therapy, which offers support for a promising outcome for melanoma patients who experience vitiligolike depigmentation.

To the Editor:

A collision tumor is the coexistence of 2 discrete tumors in the same neoplasm, possibly comprising a malignant tumor and a benign tumor, and thereby complicating appropriate diagnosis and treatment. We present a case of a basal cell carcinoma (BCC) of the scalp that was later found to be in collision with an apocrine hidrocystoma that might have arisen from a nevus sebaceus. Although rare, BCC can coexist with apocrine hidrocystoma. Jayaprakasam and Rene¹ reported a case of a collision tumor containing BCC and hidrocystoma on the eyelid.¹ We present a case of a BCC on the scalp that was later found to be in collision with an apocrine hidrocystoma that possibly arose from a nevus sebaceus.

A 92-year-old Black woman with a biopsy-confirmed primary BCC of the left parietal scalp presented for Mohs micrographic surgery. The pathology report from an outside facility was reviewed. The initial diagnosis had been made with 2 punch biopsies from separate areas of the large nodule—one consistent with nodular and pigmented BCC (Figure 1), and the other revealed nodular ulcerated BCC. Physical examination prior to Mohs surgery revealed a mobile, flesh-colored, 6.2×6.0-cm nodule with minimal overlying hair on the left parietal scalp (Figure 2). During stage-I processing by the histopathology laboratory, large cystic structures were encountered; en face frozen sections showed a cystic tumor. Excised tissue was submitted for permanent processing to aid in diagnosis; the initial diagnostic biopsy slides were requested from the outside facility for review.

The initial diagnostic biopsy slides were reviewed and found to be consistent with nodular and pigmented BCC, as previously reported. Findings from hematoxylin and eosin staining of tissue obtained from Mohs sections were consistent with a combined neoplasm comprising BCC (Figure 3A) and apocrine hidrocystoma (Figure 3B). In addition, one section was characterized by acanthosis, papillomatosis, and sebaceous glands—similar to findings that are seen in a nevus sebaceus (Figure 3C).

The BCC was cleared after stage I; the final wound size was 7×6.6 cm. Although benign apocrine hidrocystoma was still evident at the margin, further excision was not performed at the request of the patient and her family. Partial primary wound closure was performed with pulley sutures. A xenograft was placed over the unclosed central portion. The wound was permitted to heal by second intention.

The clinical differential diagnosis of a scalp nodule includes a pilar cyst, BCC, squamous cell carcinoma, melanoma, cutaneous metastasis, adnexal tumor, atypical fibroxanthoma, and collision tumor. A collision tumor—the association of 2 or more benign or malignant neoplasms—represents a well-known pitfall in making a correct clinical and pathologic diagnosis.² Many theories have been proposed to explain the pathophysiology of collision tumors. Some authors have speculated that they arise from involvement of related cell types.¹ Other theories include induction by cytokines and growth factors secreted from one tumor that provides an ideal environment for proliferation of other cell types, a field cancerization effect of sun-damaged skin, or a coincidence.²

In our case, it is possible that the 2 tumors arose from a nevus sebaceus. One retrospective study of 706 cases of nevus sebaceus (707 specimens) found that 22.5% of cases developed secondary proliferation; of those cases, 18.9% were benign.³ Additionally, in 4.2% of cases of nevus sebaceus, proliferation of 2 or more tumors developed. The most common malignant neoplasm to develop from nevus sebaceus was BCC, followed by squamous cell carcinoma and sebaceous carcinoma. The most common benign neoplasm to develop from nevus sebaceus was trichoblastoma, followed by syringocystadenoma papilliferum.³

Our case highlights the possibility of a sampling error when performing a biopsy of any large neoplasm. Additionally, Mohs surgeons should maintain high clinical suspicion for collision tumors when encountering a large tumor with pathology inconsistent with the original biopsy. Apocrine hidrocystoma should be considered in the differential diagnosis of a large cystic mass of the scalp. Also, it is important to recognize that malignant lesions, such as BCC, can coexist with another benign tumor. Basal cell carcinoma is rare in Black patients, supporting our belief that our patient’s tumors arose from a nevus sebaceus.

It also is important for Mohs surgeons to consider any potential discrepancy between the initial pathology report and Mohs intraoperative pathology that can impact diagnosis, the aggressiveness of the tumors identified, and how such aggressiveness may affect management options.^4,5 Some dermatology practices request biopsy slides from patients who are referred for Mohs micrographic surgery for internal review by a dermatopathologist before surgery is performed; however, this protocol requires additional time and adds costs for the overall health care system.⁴ One study found that internal review of outside biopsy slides resulted in a change in diagnosis in 2.2% of patients (N=3345)—affecting management in 61% of cases in which the diagnosis was changed.⁴ Another study (N=163) found that the reported aggressiveness of 50.5% of nonmelanoma cases in an initial biopsy report was changed during Mohs micrographic surgery.⁵ Mohs surgeons should be aware that discrepancies can occur, and if a discrepancy is discovered, the procedure may be paused until the initial biopsy slide is reviewed and further information is collected.

To the Editor:

A collision tumor is the coexistence of 2 discrete tumors in the same neoplasm, possibly comprising a malignant tumor and a benign tumor, and thereby complicating appropriate diagnosis and treatment. We present a case of a basal cell carcinoma (BCC) of the scalp that was later found to be in collision with an apocrine hidrocystoma that might have arisen from a nevus sebaceus. Although rare, BCC can coexist with apocrine hidrocystoma. Jayaprakasam and Rene¹ reported a case of a collision tumor containing BCC and hidrocystoma on the eyelid.¹ We present a case of a BCC on the scalp that was later found to be in collision with an apocrine hidrocystoma that possibly arose from a nevus sebaceus.

A 92-year-old Black woman with a biopsy-confirmed primary BCC of the left parietal scalp presented for Mohs micrographic surgery. The pathology report from an outside facility was reviewed. The initial diagnosis had been made with 2 punch biopsies from separate areas of the large nodule—one consistent with nodular and pigmented BCC (Figure 1), and the other revealed nodular ulcerated BCC. Physical examination prior to Mohs surgery revealed a mobile, flesh-colored, 6.2×6.0-cm nodule with minimal overlying hair on the left parietal scalp (Figure 2). During stage-I processing by the histopathology laboratory, large cystic structures were encountered; en face frozen sections showed a cystic tumor. Excised tissue was submitted for permanent processing to aid in diagnosis; the initial diagnostic biopsy slides were requested from the outside facility for review.

The initial diagnostic biopsy slides were reviewed and found to be consistent with nodular and pigmented BCC, as previously reported. Findings from hematoxylin and eosin staining of tissue obtained from Mohs sections were consistent with a combined neoplasm comprising BCC (Figure 3A) and apocrine hidrocystoma (Figure 3B). In addition, one section was characterized by acanthosis, papillomatosis, and sebaceous glands—similar to findings that are seen in a nevus sebaceus (Figure 3C).

The BCC was cleared after stage I; the final wound size was 7×6.6 cm. Although benign apocrine hidrocystoma was still evident at the margin, further excision was not performed at the request of the patient and her family. Partial primary wound closure was performed with pulley sutures. A xenograft was placed over the unclosed central portion. The wound was permitted to heal by second intention.

The clinical differential diagnosis of a scalp nodule includes a pilar cyst, BCC, squamous cell carcinoma, melanoma, cutaneous metastasis, adnexal tumor, atypical fibroxanthoma, and collision tumor. A collision tumor—the association of 2 or more benign or malignant neoplasms—represents a well-known pitfall in making a correct clinical and pathologic diagnosis.² Many theories have been proposed to explain the pathophysiology of collision tumors. Some authors have speculated that they arise from involvement of related cell types.¹ Other theories include induction by cytokines and growth factors secreted from one tumor that provides an ideal environment for proliferation of other cell types, a field cancerization effect of sun-damaged skin, or a coincidence.²

In our case, it is possible that the 2 tumors arose from a nevus sebaceus. One retrospective study of 706 cases of nevus sebaceus (707 specimens) found that 22.5% of cases developed secondary proliferation; of those cases, 18.9% were benign.³ Additionally, in 4.2% of cases of nevus sebaceus, proliferation of 2 or more tumors developed. The most common malignant neoplasm to develop from nevus sebaceus was BCC, followed by squamous cell carcinoma and sebaceous carcinoma. The most common benign neoplasm to develop from nevus sebaceus was trichoblastoma, followed by syringocystadenoma papilliferum.³

Our case highlights the possibility of a sampling error when performing a biopsy of any large neoplasm. Additionally, Mohs surgeons should maintain high clinical suspicion for collision tumors when encountering a large tumor with pathology inconsistent with the original biopsy. Apocrine hidrocystoma should be considered in the differential diagnosis of a large cystic mass of the scalp. Also, it is important to recognize that malignant lesions, such as BCC, can coexist with another benign tumor. Basal cell carcinoma is rare in Black patients, supporting our belief that our patient’s tumors arose from a nevus sebaceus.

It also is important for Mohs surgeons to consider any potential discrepancy between the initial pathology report and Mohs intraoperative pathology that can impact diagnosis, the aggressiveness of the tumors identified, and how such aggressiveness may affect management options.^4,5 Some dermatology practices request biopsy slides from patients who are referred for Mohs micrographic surgery for internal review by a dermatopathologist before surgery is performed; however, this protocol requires additional time and adds costs for the overall health care system.⁴ One study found that internal review of outside biopsy slides resulted in a change in diagnosis in 2.2% of patients (N=3345)—affecting management in 61% of cases in which the diagnosis was changed.⁴ Another study (N=163) found that the reported aggressiveness of 50.5% of nonmelanoma cases in an initial biopsy report was changed during Mohs micrographic surgery.⁵ Mohs surgeons should be aware that discrepancies can occur, and if a discrepancy is discovered, the procedure may be paused until the initial biopsy slide is reviewed and further information is collected.

To the Editor:

A collision tumor is the coexistence of 2 discrete tumors in the same neoplasm, possibly comprising a malignant tumor and a benign tumor, and thereby complicating appropriate diagnosis and treatment. We present a case of a basal cell carcinoma (BCC) of the scalp that was later found to be in collision with an apocrine hidrocystoma that might have arisen from a nevus sebaceus. Although rare, BCC can coexist with apocrine hidrocystoma. Jayaprakasam and Rene¹ reported a case of a collision tumor containing BCC and hidrocystoma on the eyelid.¹ We present a case of a BCC on the scalp that was later found to be in collision with an apocrine hidrocystoma that possibly arose from a nevus sebaceus.

A 92-year-old Black woman with a biopsy-confirmed primary BCC of the left parietal scalp presented for Mohs micrographic surgery. The pathology report from an outside facility was reviewed. The initial diagnosis had been made with 2 punch biopsies from separate areas of the large nodule—one consistent with nodular and pigmented BCC (Figure 1), and the other revealed nodular ulcerated BCC. Physical examination prior to Mohs surgery revealed a mobile, flesh-colored, 6.2×6.0-cm nodule with minimal overlying hair on the left parietal scalp (Figure 2). During stage-I processing by the histopathology laboratory, large cystic structures were encountered; en face frozen sections showed a cystic tumor. Excised tissue was submitted for permanent processing to aid in diagnosis; the initial diagnostic biopsy slides were requested from the outside facility for review.

The initial diagnostic biopsy slides were reviewed and found to be consistent with nodular and pigmented BCC, as previously reported. Findings from hematoxylin and eosin staining of tissue obtained from Mohs sections were consistent with a combined neoplasm comprising BCC (Figure 3A) and apocrine hidrocystoma (Figure 3B). In addition, one section was characterized by acanthosis, papillomatosis, and sebaceous glands—similar to findings that are seen in a nevus sebaceus (Figure 3C).

The BCC was cleared after stage I; the final wound size was 7×6.6 cm. Although benign apocrine hidrocystoma was still evident at the margin, further excision was not performed at the request of the patient and her family. Partial primary wound closure was performed with pulley sutures. A xenograft was placed over the unclosed central portion. The wound was permitted to heal by second intention.

The clinical differential diagnosis of a scalp nodule includes a pilar cyst, BCC, squamous cell carcinoma, melanoma, cutaneous metastasis, adnexal tumor, atypical fibroxanthoma, and collision tumor. A collision tumor—the association of 2 or more benign or malignant neoplasms—represents a well-known pitfall in making a correct clinical and pathologic diagnosis.² Many theories have been proposed to explain the pathophysiology of collision tumors. Some authors have speculated that they arise from involvement of related cell types.¹ Other theories include induction by cytokines and growth factors secreted from one tumor that provides an ideal environment for proliferation of other cell types, a field cancerization effect of sun-damaged skin, or a coincidence.²

In our case, it is possible that the 2 tumors arose from a nevus sebaceus. One retrospective study of 706 cases of nevus sebaceus (707 specimens) found that 22.5% of cases developed secondary proliferation; of those cases, 18.9% were benign.³ Additionally, in 4.2% of cases of nevus sebaceus, proliferation of 2 or more tumors developed. The most common malignant neoplasm to develop from nevus sebaceus was BCC, followed by squamous cell carcinoma and sebaceous carcinoma. The most common benign neoplasm to develop from nevus sebaceus was trichoblastoma, followed by syringocystadenoma papilliferum.³

Our case highlights the possibility of a sampling error when performing a biopsy of any large neoplasm. Additionally, Mohs surgeons should maintain high clinical suspicion for collision tumors when encountering a large tumor with pathology inconsistent with the original biopsy. Apocrine hidrocystoma should be considered in the differential diagnosis of a large cystic mass of the scalp. Also, it is important to recognize that malignant lesions, such as BCC, can coexist with another benign tumor. Basal cell carcinoma is rare in Black patients, supporting our belief that our patient’s tumors arose from a nevus sebaceus.

It also is important for Mohs surgeons to consider any potential discrepancy between the initial pathology report and Mohs intraoperative pathology that can impact diagnosis, the aggressiveness of the tumors identified, and how such aggressiveness may affect management options.^4,5 Some dermatology practices request biopsy slides from patients who are referred for Mohs micrographic surgery for internal review by a dermatopathologist before surgery is performed; however, this protocol requires additional time and adds costs for the overall health care system.⁴ One study found that internal review of outside biopsy slides resulted in a change in diagnosis in 2.2% of patients (N=3345)—affecting management in 61% of cases in which the diagnosis was changed.⁴ Another study (N=163) found that the reported aggressiveness of 50.5% of nonmelanoma cases in an initial biopsy report was changed during Mohs micrographic surgery.⁵ Mohs surgeons should be aware that discrepancies can occur, and if a discrepancy is discovered, the procedure may be paused until the initial biopsy slide is reviewed and further information is collected.

Dercum disease (or adiposis dolorosa) is a rare condition of unknown etiology characterized by multiple painful lipomas localized throughout the body.^1,2 It typically presents in adults aged 35 to 50 years and is at least 5 times more common in women.³ It often is associated with comorbidities such as obesity, fatigue and weakness.¹ There currently are no approved treatments for Dercum disease, only therapies tried with little to no efficacy for symptom management, including analgesics, excision, liposuction,¹ lymphatic drainage,⁴ hypobaric pressure,⁵ and frequency rhythmic electrical modulation systems.⁶ For patients who continually develop widespread lesions, surgical excision is not feasible, which poses a therapeutic challenge. Deoxycholic acid (DCA), a bile acid that is approved to treat submental fat, disrupts the integrity of cell membranes, induces adipocyte lysis, and solubilizes fat when injected subcutaneously.⁷ We used DCA to mitigate pain and reduce lipoma size in patients with Dercum disease, which demonstrated lipoma reduction via ultrasonography in 3 patients.

Case Reports

Three patients presented to clinic with multiple painful subcutaneous nodules throughout several areas of the body and were screened using radiography. Ultrasonography demonstrated numerous lipomas consistent with Dercum disease. The lipomas were measured by ultrasonography to obtain 3-dimensional measurements of each lesion. The most painful lipomas identified by the patients were either treated with 2 mL of DCA (10 mg/mL) or served as a control with no treatment. Patients returned for symptom monitoring and repeat measurements of both treated and untreated lipomas. Two physicians with expertise in ultrasonography measured lesions in a blinded fashion. Photographs were obtained with patient consent.

Patient 1—A 45-year-old woman with a family history of lipomas was diagnosed with Dercum disease that was confirmed via ultrasonography. A painful 1.63×1.64×0.55-cm lipoma was measured on the volar aspect of the left forearm, and a 1.17×1.26×0.39-cm lipoma was measured on the volar aspect of the right wrist. At a follow-up visit 11 months later, 2 mL of DCA was administered to the lipoma on the volar aspect of the left forearm, while the lipoma on the volar aspect of the right wrist was monitored as an untreated control. Following the procedure, the patient reported 1 week of swelling and tenderness of the treated area. Repeat imaging 4 months after administration of DCA revealed reduction of the treated lesion to 0.80×1.48×0.60 cm and growth of the untreated lesion to 1.32×2.17×0.52 cm. The treated lipoma reduced in volume by 34.55%, while the lipoma in the untreated control increased in volume from its original measurement by 111.11% (Table). The patient also reported decreased pain in the treated area at all follow-up visits in the 1 year following the procedure.

Patient 2—A 42-year-old woman with Dercum disease received administration of 2 mL of DCA to a 1.90×1.70×0.90-cm lipoma of the lateral aspect of the left mid thigh and 2 mL of DCA to a 2.40×3.07×0.60-cm lipoma on the volar aspect of the right forearm 2 weeks later. A 1.18×0.91×0.45-cm lipoma of the volar aspect of the left forearm was monitored as an untreated control. The patient reported bruising and discoloration a few weeks following the procedure. At subsequent 1-month and 3-month follow-ups, the patient reported induration in the volar aspect of the right forearm and noticeable reduction in size of the lesion in the lateral aspect of the left mid thigh. At the 6-month follow-up, the patient reported reduction in size of both lesions and improvement of the previously noted side effects. Repeat ultrasonography approximately 6 months after administration of DCA demonstrated reduction of the treated lesion on the lateral aspect of the left mid thigh to 0.92×0.96×0.57 cm and the volar aspect of the right forearm to 1.56×2.18×0.79 cm, with growth of the untreated lesion on the volar aspect of the left forearm to 1.37×1.11×0.39 cm. The treated lipomas reduced in volume by 68.42% and 41.25%, respectively, and the untreated control increased in volume by 22.08% (Table).

Patient 3—A 75-year-old woman with a family history of lipomas was diagnosed with Dercum disease verified by ultrasonography. The patient was administered 2 mL of DCA to a 2.65×3.19×0.71-cm lipoma of the volar aspect of the left forearm. A 1.66×2.02×0.38-cm lipoma of the lateral aspect of the right forearm was monitored as an untreated control. Following the procedure, the patient reported initial swelling that persisted for a few weeks followed by notable pain relief and a decrease in lipoma size. At 2-month follow-up, the patient reported no pain or other adverse effects, while repeat imaging demonstrated reduction of the treated lesion on the volar aspect of the left forearm to 2.13×2.56×0.75 cm and growth of the untreated lesion on the lateral aspect of the right forearm to 1.95×2.05×0.37 cm. The treated lipoma reduced in volume by 30.29%, and the untreated control increased in volume by 15.05% (Table).

Comment

Deoxycholic acid is a bile acid naturally found in the body that helps to emulsify and solubilize fats in the intestines. When injected subcutaneously, DCA becomes an adipolytic agent that induces inflammation and targets adipose degradation by macrophages, and it has been manufactured to reduce submental fat.⁷ Off-label use of DCA has been explored for nonsurgical body contouring and lipomas with promising results in some cases; however, these prior studies have been limited by the lack of quantitative objective measurements to effectively demonstrate the impact of treatment.^8,9

We present 3 patients who requested treatment for numerous painful lipomas. Given the extent of their disease, surgical options were not feasible, and the patients opted to try a nonsurgical alternative. In each case, the painful lipomas that were chosen for treatment were injected with 2 mL of DCA. Injection-associated symptoms included swelling, tenderness, discoloration, and induration, which resolved over a period of months. Patient 1 had a treated lipoma that reduced in volume by approximately 35%, while the control continued to grow and doubled in volume. In patient 2, the treated lesion on the lateral aspect of the mid thigh reduced in volume by almost 70%, and the treated lesion on the volar aspect of the right forearm reduced in volume by more than 40%, while the control grew by more than 20%. In patient 3, the volume of the treated lipoma decreased by 30%, and the control increased by 15%. The follow-up interval was shortest in patient 3—2 months as opposed to 11 months and 6 months for patients 1 and 2, respectively; therefore, more progress may be seen in patient 3 with more time. Interestingly, a change in shape of the lipoma was noted in patient 3 (Figure)—an increase in its depth while the center became anechoic, which is a sign of hollowing in the center due to the saponification of fat and a possible cause for the change from an elliptical to a more spherical or doughnutlike shape. Intralesional administration of DCA may offer patients with extensive lipomas, such as those seen in patients with Dercum disease, an alternative, less-invasive option to assist with pain and tumor burden when excision is not feasible. Although treatments with DCA can be associated with side effects, including pain, swelling, bruising, erythema, induration, and numbness, all 3 of our patients had ultimate mitigation of pain and reduction in lipoma size within months of the injection. Additional studies should be explored to determine the optimal dose and frequency of administration of DCA that could benefit patients with Dercum disease.

Dercum disease (or adiposis dolorosa) is a rare condition of unknown etiology characterized by multiple painful lipomas localized throughout the body.^1,2 It typically presents in adults aged 35 to 50 years and is at least 5 times more common in women.³ It often is associated with comorbidities such as obesity, fatigue and weakness.¹ There currently are no approved treatments for Dercum disease, only therapies tried with little to no efficacy for symptom management, including analgesics, excision, liposuction,¹ lymphatic drainage,⁴ hypobaric pressure,⁵ and frequency rhythmic electrical modulation systems.⁶ For patients who continually develop widespread lesions, surgical excision is not feasible, which poses a therapeutic challenge. Deoxycholic acid (DCA), a bile acid that is approved to treat submental fat, disrupts the integrity of cell membranes, induces adipocyte lysis, and solubilizes fat when injected subcutaneously.⁷ We used DCA to mitigate pain and reduce lipoma size in patients with Dercum disease, which demonstrated lipoma reduction via ultrasonography in 3 patients.

Case Reports

Three patients presented to clinic with multiple painful subcutaneous nodules throughout several areas of the body and were screened using radiography. Ultrasonography demonstrated numerous lipomas consistent with Dercum disease. The lipomas were measured by ultrasonography to obtain 3-dimensional measurements of each lesion. The most painful lipomas identified by the patients were either treated with 2 mL of DCA (10 mg/mL) or served as a control with no treatment. Patients returned for symptom monitoring and repeat measurements of both treated and untreated lipomas. Two physicians with expertise in ultrasonography measured lesions in a blinded fashion. Photographs were obtained with patient consent.

Patient 1—A 45-year-old woman with a family history of lipomas was diagnosed with Dercum disease that was confirmed via ultrasonography. A painful 1.63×1.64×0.55-cm lipoma was measured on the volar aspect of the left forearm, and a 1.17×1.26×0.39-cm lipoma was measured on the volar aspect of the right wrist. At a follow-up visit 11 months later, 2 mL of DCA was administered to the lipoma on the volar aspect of the left forearm, while the lipoma on the volar aspect of the right wrist was monitored as an untreated control. Following the procedure, the patient reported 1 week of swelling and tenderness of the treated area. Repeat imaging 4 months after administration of DCA revealed reduction of the treated lesion to 0.80×1.48×0.60 cm and growth of the untreated lesion to 1.32×2.17×0.52 cm. The treated lipoma reduced in volume by 34.55%, while the lipoma in the untreated control increased in volume from its original measurement by 111.11% (Table). The patient also reported decreased pain in the treated area at all follow-up visits in the 1 year following the procedure.

Patient 2—A 42-year-old woman with Dercum disease received administration of 2 mL of DCA to a 1.90×1.70×0.90-cm lipoma of the lateral aspect of the left mid thigh and 2 mL of DCA to a 2.40×3.07×0.60-cm lipoma on the volar aspect of the right forearm 2 weeks later. A 1.18×0.91×0.45-cm lipoma of the volar aspect of the left forearm was monitored as an untreated control. The patient reported bruising and discoloration a few weeks following the procedure. At subsequent 1-month and 3-month follow-ups, the patient reported induration in the volar aspect of the right forearm and noticeable reduction in size of the lesion in the lateral aspect of the left mid thigh. At the 6-month follow-up, the patient reported reduction in size of both lesions and improvement of the previously noted side effects. Repeat ultrasonography approximately 6 months after administration of DCA demonstrated reduction of the treated lesion on the lateral aspect of the left mid thigh to 0.92×0.96×0.57 cm and the volar aspect of the right forearm to 1.56×2.18×0.79 cm, with growth of the untreated lesion on the volar aspect of the left forearm to 1.37×1.11×0.39 cm. The treated lipomas reduced in volume by 68.42% and 41.25%, respectively, and the untreated control increased in volume by 22.08% (Table).

Patient 3—A 75-year-old woman with a family history of lipomas was diagnosed with Dercum disease verified by ultrasonography. The patient was administered 2 mL of DCA to a 2.65×3.19×0.71-cm lipoma of the volar aspect of the left forearm. A 1.66×2.02×0.38-cm lipoma of the lateral aspect of the right forearm was monitored as an untreated control. Following the procedure, the patient reported initial swelling that persisted for a few weeks followed by notable pain relief and a decrease in lipoma size. At 2-month follow-up, the patient reported no pain or other adverse effects, while repeat imaging demonstrated reduction of the treated lesion on the volar aspect of the left forearm to 2.13×2.56×0.75 cm and growth of the untreated lesion on the lateral aspect of the right forearm to 1.95×2.05×0.37 cm. The treated lipoma reduced in volume by 30.29%, and the untreated control increased in volume by 15.05% (Table).

Comment

Deoxycholic acid is a bile acid naturally found in the body that helps to emulsify and solubilize fats in the intestines. When injected subcutaneously, DCA becomes an adipolytic agent that induces inflammation and targets adipose degradation by macrophages, and it has been manufactured to reduce submental fat.⁷ Off-label use of DCA has been explored for nonsurgical body contouring and lipomas with promising results in some cases; however, these prior studies have been limited by the lack of quantitative objective measurements to effectively demonstrate the impact of treatment.^8,9

We present 3 patients who requested treatment for numerous painful lipomas. Given the extent of their disease, surgical options were not feasible, and the patients opted to try a nonsurgical alternative. In each case, the painful lipomas that were chosen for treatment were injected with 2 mL of DCA. Injection-associated symptoms included swelling, tenderness, discoloration, and induration, which resolved over a period of months. Patient 1 had a treated lipoma that reduced in volume by approximately 35%, while the control continued to grow and doubled in volume. In patient 2, the treated lesion on the lateral aspect of the mid thigh reduced in volume by almost 70%, and the treated lesion on the volar aspect of the right forearm reduced in volume by more than 40%, while the control grew by more than 20%. In patient 3, the volume of the treated lipoma decreased by 30%, and the control increased by 15%. The follow-up interval was shortest in patient 3—2 months as opposed to 11 months and 6 months for patients 1 and 2, respectively; therefore, more progress may be seen in patient 3 with more time. Interestingly, a change in shape of the lipoma was noted in patient 3 (Figure)—an increase in its depth while the center became anechoic, which is a sign of hollowing in the center due to the saponification of fat and a possible cause for the change from an elliptical to a more spherical or doughnutlike shape. Intralesional administration of DCA may offer patients with extensive lipomas, such as those seen in patients with Dercum disease, an alternative, less-invasive option to assist with pain and tumor burden when excision is not feasible. Although treatments with DCA can be associated with side effects, including pain, swelling, bruising, erythema, induration, and numbness, all 3 of our patients had ultimate mitigation of pain and reduction in lipoma size within months of the injection. Additional studies should be explored to determine the optimal dose and frequency of administration of DCA that could benefit patients with Dercum disease.

Dercum disease (or adiposis dolorosa) is a rare condition of unknown etiology characterized by multiple painful lipomas localized throughout the body.^1,2 It typically presents in adults aged 35 to 50 years and is at least 5 times more common in women.³ It often is associated with comorbidities such as obesity, fatigue and weakness.¹ There currently are no approved treatments for Dercum disease, only therapies tried with little to no efficacy for symptom management, including analgesics, excision, liposuction,¹ lymphatic drainage,⁴ hypobaric pressure,⁵ and frequency rhythmic electrical modulation systems.⁶ For patients who continually develop widespread lesions, surgical excision is not feasible, which poses a therapeutic challenge. Deoxycholic acid (DCA), a bile acid that is approved to treat submental fat, disrupts the integrity of cell membranes, induces adipocyte lysis, and solubilizes fat when injected subcutaneously.⁷ We used DCA to mitigate pain and reduce lipoma size in patients with Dercum disease, which demonstrated lipoma reduction via ultrasonography in 3 patients.

Case Reports

Three patients presented to clinic with multiple painful subcutaneous nodules throughout several areas of the body and were screened using radiography. Ultrasonography demonstrated numerous lipomas consistent with Dercum disease. The lipomas were measured by ultrasonography to obtain 3-dimensional measurements of each lesion. The most painful lipomas identified by the patients were either treated with 2 mL of DCA (10 mg/mL) or served as a control with no treatment. Patients returned for symptom monitoring and repeat measurements of both treated and untreated lipomas. Two physicians with expertise in ultrasonography measured lesions in a blinded fashion. Photographs were obtained with patient consent.

Patient 1—A 45-year-old woman with a family history of lipomas was diagnosed with Dercum disease that was confirmed via ultrasonography. A painful 1.63×1.64×0.55-cm lipoma was measured on the volar aspect of the left forearm, and a 1.17×1.26×0.39-cm lipoma was measured on the volar aspect of the right wrist. At a follow-up visit 11 months later, 2 mL of DCA was administered to the lipoma on the volar aspect of the left forearm, while the lipoma on the volar aspect of the right wrist was monitored as an untreated control. Following the procedure, the patient reported 1 week of swelling and tenderness of the treated area. Repeat imaging 4 months after administration of DCA revealed reduction of the treated lesion to 0.80×1.48×0.60 cm and growth of the untreated lesion to 1.32×2.17×0.52 cm. The treated lipoma reduced in volume by 34.55%, while the lipoma in the untreated control increased in volume from its original measurement by 111.11% (Table). The patient also reported decreased pain in the treated area at all follow-up visits in the 1 year following the procedure.

Patient 2—A 42-year-old woman with Dercum disease received administration of 2 mL of DCA to a 1.90×1.70×0.90-cm lipoma of the lateral aspect of the left mid thigh and 2 mL of DCA to a 2.40×3.07×0.60-cm lipoma on the volar aspect of the right forearm 2 weeks later. A 1.18×0.91×0.45-cm lipoma of the volar aspect of the left forearm was monitored as an untreated control. The patient reported bruising and discoloration a few weeks following the procedure. At subsequent 1-month and 3-month follow-ups, the patient reported induration in the volar aspect of the right forearm and noticeable reduction in size of the lesion in the lateral aspect of the left mid thigh. At the 6-month follow-up, the patient reported reduction in size of both lesions and improvement of the previously noted side effects. Repeat ultrasonography approximately 6 months after administration of DCA demonstrated reduction of the treated lesion on the lateral aspect of the left mid thigh to 0.92×0.96×0.57 cm and the volar aspect of the right forearm to 1.56×2.18×0.79 cm, with growth of the untreated lesion on the volar aspect of the left forearm to 1.37×1.11×0.39 cm. The treated lipomas reduced in volume by 68.42% and 41.25%, respectively, and the untreated control increased in volume by 22.08% (Table).

Patient 3—A 75-year-old woman with a family history of lipomas was diagnosed with Dercum disease verified by ultrasonography. The patient was administered 2 mL of DCA to a 2.65×3.19×0.71-cm lipoma of the volar aspect of the left forearm. A 1.66×2.02×0.38-cm lipoma of the lateral aspect of the right forearm was monitored as an untreated control. Following the procedure, the patient reported initial swelling that persisted for a few weeks followed by notable pain relief and a decrease in lipoma size. At 2-month follow-up, the patient reported no pain or other adverse effects, while repeat imaging demonstrated reduction of the treated lesion on the volar aspect of the left forearm to 2.13×2.56×0.75 cm and growth of the untreated lesion on the lateral aspect of the right forearm to 1.95×2.05×0.37 cm. The treated lipoma reduced in volume by 30.29%, and the untreated control increased in volume by 15.05% (Table).

Comment

Deoxycholic acid is a bile acid naturally found in the body that helps to emulsify and solubilize fats in the intestines. When injected subcutaneously, DCA becomes an adipolytic agent that induces inflammation and targets adipose degradation by macrophages, and it has been manufactured to reduce submental fat.⁷ Off-label use of DCA has been explored for nonsurgical body contouring and lipomas with promising results in some cases; however, these prior studies have been limited by the lack of quantitative objective measurements to effectively demonstrate the impact of treatment.^8,9

We present 3 patients who requested treatment for numerous painful lipomas. Given the extent of their disease, surgical options were not feasible, and the patients opted to try a nonsurgical alternative. In each case, the painful lipomas that were chosen for treatment were injected with 2 mL of DCA. Injection-associated symptoms included swelling, tenderness, discoloration, and induration, which resolved over a period of months. Patient 1 had a treated lipoma that reduced in volume by approximately 35%, while the control continued to grow and doubled in volume. In patient 2, the treated lesion on the lateral aspect of the mid thigh reduced in volume by almost 70%, and the treated lesion on the volar aspect of the right forearm reduced in volume by more than 40%, while the control grew by more than 20%. In patient 3, the volume of the treated lipoma decreased by 30%, and the control increased by 15%. The follow-up interval was shortest in patient 3—2 months as opposed to 11 months and 6 months for patients 1 and 2, respectively; therefore, more progress may be seen in patient 3 with more time. Interestingly, a change in shape of the lipoma was noted in patient 3 (Figure)—an increase in its depth while the center became anechoic, which is a sign of hollowing in the center due to the saponification of fat and a possible cause for the change from an elliptical to a more spherical or doughnutlike shape. Intralesional administration of DCA may offer patients with extensive lipomas, such as those seen in patients with Dercum disease, an alternative, less-invasive option to assist with pain and tumor burden when excision is not feasible. Although treatments with DCA can be associated with side effects, including pain, swelling, bruising, erythema, induration, and numbness, all 3 of our patients had ultimate mitigation of pain and reduction in lipoma size within months of the injection. Additional studies should be explored to determine the optimal dose and frequency of administration of DCA that could benefit patients with Dercum disease.

The Diagnosis: Neonatal-Onset Multisystem Inflammatory Disorder (NOMID)

The punch biopsy demonstrated a predominantly deep but somewhat superficial, periadnexal, neutrophilic and eosinophilic infiltrate (Figure). The eruption resolved 3 days later with supportive treatment, including appropriate wound care. Genetic analysis revealed an autosomal-dominant NLR family pyrin domain containing 3 gene, NLRP3, de novo variant associated with neonatal-onset multisystem inflammatory disorder (NOMID). Additional workup to characterize our patient’s inflammatory profile revealed elevated IL-18, CD3, CD4, S100A12, and S100A8/A9 levels. On day 48 of life, she was started on anakinra, an IL-1 inhibitor, at a dose of 1 mg/kg subcutaneously, which eventually was titrated to 10 mg/kg at hospital discharge. Hearing screenings were within normal limits.

Cryopyrin-associated periodic syndromes (CAPS) consist of 3 rare, IL-1–associated, autoinflammatory disorders, including familial cold autoinflammatory syndrome (FCAS), Muckle-Wells syndrome (MWS), and NOMID (also known as chronic infantile neurologic cutaneous and articular syndrome). These conditions result from a sporadic or autosomal-dominant gain-of-function mutations in a single gene, NLRP3, on chromosome 1q44. NLRP3 encodes for cryopyrin, an important component of an IL-1 and IL-18 activating inflammasome.¹ The most severe manifestation of CAPS is NOMID, which typically presents at birth as a migratory urticarial eruption, growth failure, myalgia, fever, and abnormal facial features, including frontal bossing, saddle-shaped nose, and protruding eyes.² The illness also can manifest with hepatosplenomegaly, lymphadenopathy, uveitis, sensorineural hearing loss, cerebral atrophy, and other neurologic manifestations.³ A diagnosis of chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature (CANDLE) syndrome was less likely given that our patient remained afebrile and did not show signs of lipodystrophy and persistent violaceous eyelid swelling. Both FCAS and MWS are less severe forms of CAPS when compared to NOMID. Familial cold autoinflammatory syndrome was less likely given the absence of the typical periodic fever pattern associated with the condition and severity of our patient’s symptoms. Muckle-Wells syndrome typically presents in adolescence with symptoms of FCAS, painful urticarial plaques, and progressive sensorinueral hearing loss. Tumor necrosis factor receptor–associated periodic fever (TRAPS) usually is associated with episodic fevers, abdominal pain, periorbital edema, migratory erythema, and arthralgia.^1,3,4

Diagnostic criteria for CAPS include elevated inflammatory markers and serum amyloid, plus at least 2 of the typical CAPS symptoms: urticarial rash, cold-triggered episodes, sensorineural hearing loss, musculoskeletal symptoms, chronic aseptic meningitis, and skeletal abnormalities.⁴ The sensitivity and specificity of these diagnostic criteria are 84% and 91%, respectively. Additional findings that can be seen but are not part of the diagnostic criteria include intermittent fever, transient joint swelling, bony overgrowths, uveitis, optic disc edema, impaired growth, and hepatosplenomegaly.⁵ Laboratory findings may reveal leukocytosis, eosinophilia, anemia, and/or thrombocytopenia.^3,5

Genetic testing, skin biopsies, ophthalmic examinations, neuroimaging, joint radiography, cerebrospinal fluid tests, and hearing examinations can be performed for confirmation of diagnosis and evaluation of systemic complications.⁴ A skin biopsy may reveal a neutrophilic infiltrate. Ophthalmic examination can demonstrate uveitis and optic disk edema. Neuroimaging may reveal cerebral atrophy or ventricular dilation. Lastly, joint radiography can be used to evaluate for the presence of premature long bone ossification or osseous overgrowth.⁴

In summary, NOMID is a multisystemic disorder with cutaneous manifestations. Early recognition of this entity is important given the severe sequelae and available efficacious therapy. Dermatologists should be aware of these manifestations, as dermatologic consultation and a skin biopsy may aid in diagnosis.

The Diagnosis: Neonatal-Onset Multisystem Inflammatory Disorder (NOMID)

The punch biopsy demonstrated a predominantly deep but somewhat superficial, periadnexal, neutrophilic and eosinophilic infiltrate (Figure). The eruption resolved 3 days later with supportive treatment, including appropriate wound care. Genetic analysis revealed an autosomal-dominant NLR family pyrin domain containing 3 gene, NLRP3, de novo variant associated with neonatal-onset multisystem inflammatory disorder (NOMID). Additional workup to characterize our patient’s inflammatory profile revealed elevated IL-18, CD3, CD4, S100A12, and S100A8/A9 levels. On day 48 of life, she was started on anakinra, an IL-1 inhibitor, at a dose of 1 mg/kg subcutaneously, which eventually was titrated to 10 mg/kg at hospital discharge. Hearing screenings were within normal limits.

Cryopyrin-associated periodic syndromes (CAPS) consist of 3 rare, IL-1–associated, autoinflammatory disorders, including familial cold autoinflammatory syndrome (FCAS), Muckle-Wells syndrome (MWS), and NOMID (also known as chronic infantile neurologic cutaneous and articular syndrome). These conditions result from a sporadic or autosomal-dominant gain-of-function mutations in a single gene, NLRP3, on chromosome 1q44. NLRP3 encodes for cryopyrin, an important component of an IL-1 and IL-18 activating inflammasome.¹ The most severe manifestation of CAPS is NOMID, which typically presents at birth as a migratory urticarial eruption, growth failure, myalgia, fever, and abnormal facial features, including frontal bossing, saddle-shaped nose, and protruding eyes.² The illness also can manifest with hepatosplenomegaly, lymphadenopathy, uveitis, sensorineural hearing loss, cerebral atrophy, and other neurologic manifestations.³ A diagnosis of chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature (CANDLE) syndrome was less likely given that our patient remained afebrile and did not show signs of lipodystrophy and persistent violaceous eyelid swelling. Both FCAS and MWS are less severe forms of CAPS when compared to NOMID. Familial cold autoinflammatory syndrome was less likely given the absence of the typical periodic fever pattern associated with the condition and severity of our patient’s symptoms. Muckle-Wells syndrome typically presents in adolescence with symptoms of FCAS, painful urticarial plaques, and progressive sensorinueral hearing loss. Tumor necrosis factor receptor–associated periodic fever (TRAPS) usually is associated with episodic fevers, abdominal pain, periorbital edema, migratory erythema, and arthralgia.^1,3,4

Diagnostic criteria for CAPS include elevated inflammatory markers and serum amyloid, plus at least 2 of the typical CAPS symptoms: urticarial rash, cold-triggered episodes, sensorineural hearing loss, musculoskeletal symptoms, chronic aseptic meningitis, and skeletal abnormalities.⁴ The sensitivity and specificity of these diagnostic criteria are 84% and 91%, respectively. Additional findings that can be seen but are not part of the diagnostic criteria include intermittent fever, transient joint swelling, bony overgrowths, uveitis, optic disc edema, impaired growth, and hepatosplenomegaly.⁵ Laboratory findings may reveal leukocytosis, eosinophilia, anemia, and/or thrombocytopenia.^3,5

Genetic testing, skin biopsies, ophthalmic examinations, neuroimaging, joint radiography, cerebrospinal fluid tests, and hearing examinations can be performed for confirmation of diagnosis and evaluation of systemic complications.⁴ A skin biopsy may reveal a neutrophilic infiltrate. Ophthalmic examination can demonstrate uveitis and optic disk edema. Neuroimaging may reveal cerebral atrophy or ventricular dilation. Lastly, joint radiography can be used to evaluate for the presence of premature long bone ossification or osseous overgrowth.⁴

In summary, NOMID is a multisystemic disorder with cutaneous manifestations. Early recognition of this entity is important given the severe sequelae and available efficacious therapy. Dermatologists should be aware of these manifestations, as dermatologic consultation and a skin biopsy may aid in diagnosis.

The Diagnosis: Neonatal-Onset Multisystem Inflammatory Disorder (NOMID)

The punch biopsy demonstrated a predominantly deep but somewhat superficial, periadnexal, neutrophilic and eosinophilic infiltrate (Figure). The eruption resolved 3 days later with supportive treatment, including appropriate wound care. Genetic analysis revealed an autosomal-dominant NLR family pyrin domain containing 3 gene, NLRP3, de novo variant associated with neonatal-onset multisystem inflammatory disorder (NOMID). Additional workup to characterize our patient’s inflammatory profile revealed elevated IL-18, CD3, CD4, S100A12, and S100A8/A9 levels. On day 48 of life, she was started on anakinra, an IL-1 inhibitor, at a dose of 1 mg/kg subcutaneously, which eventually was titrated to 10 mg/kg at hospital discharge. Hearing screenings were within normal limits.

Cryopyrin-associated periodic syndromes (CAPS) consist of 3 rare, IL-1–associated, autoinflammatory disorders, including familial cold autoinflammatory syndrome (FCAS), Muckle-Wells syndrome (MWS), and NOMID (also known as chronic infantile neurologic cutaneous and articular syndrome). These conditions result from a sporadic or autosomal-dominant gain-of-function mutations in a single gene, NLRP3, on chromosome 1q44. NLRP3 encodes for cryopyrin, an important component of an IL-1 and IL-18 activating inflammasome.¹ The most severe manifestation of CAPS is NOMID, which typically presents at birth as a migratory urticarial eruption, growth failure, myalgia, fever, and abnormal facial features, including frontal bossing, saddle-shaped nose, and protruding eyes.² The illness also can manifest with hepatosplenomegaly, lymphadenopathy, uveitis, sensorineural hearing loss, cerebral atrophy, and other neurologic manifestations.³ A diagnosis of chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature (CANDLE) syndrome was less likely given that our patient remained afebrile and did not show signs of lipodystrophy and persistent violaceous eyelid swelling. Both FCAS and MWS are less severe forms of CAPS when compared to NOMID. Familial cold autoinflammatory syndrome was less likely given the absence of the typical periodic fever pattern associated with the condition and severity of our patient’s symptoms. Muckle-Wells syndrome typically presents in adolescence with symptoms of FCAS, painful urticarial plaques, and progressive sensorinueral hearing loss. Tumor necrosis factor receptor–associated periodic fever (TRAPS) usually is associated with episodic fevers, abdominal pain, periorbital edema, migratory erythema, and arthralgia.^1,3,4

Diagnostic criteria for CAPS include elevated inflammatory markers and serum amyloid, plus at least 2 of the typical CAPS symptoms: urticarial rash, cold-triggered episodes, sensorineural hearing loss, musculoskeletal symptoms, chronic aseptic meningitis, and skeletal abnormalities.⁴ The sensitivity and specificity of these diagnostic criteria are 84% and 91%, respectively. Additional findings that can be seen but are not part of the diagnostic criteria include intermittent fever, transient joint swelling, bony overgrowths, uveitis, optic disc edema, impaired growth, and hepatosplenomegaly.⁵ Laboratory findings may reveal leukocytosis, eosinophilia, anemia, and/or thrombocytopenia.^3,5

Genetic testing, skin biopsies, ophthalmic examinations, neuroimaging, joint radiography, cerebrospinal fluid tests, and hearing examinations can be performed for confirmation of diagnosis and evaluation of systemic complications.⁴ A skin biopsy may reveal a neutrophilic infiltrate. Ophthalmic examination can demonstrate uveitis and optic disk edema. Neuroimaging may reveal cerebral atrophy or ventricular dilation. Lastly, joint radiography can be used to evaluate for the presence of premature long bone ossification or osseous overgrowth.⁴

In summary, NOMID is a multisystemic disorder with cutaneous manifestations. Early recognition of this entity is important given the severe sequelae and available efficacious therapy. Dermatologists should be aware of these manifestations, as dermatologic consultation and a skin biopsy may aid in diagnosis.

The Diagnosis: Type I Cryoglobulinemia

Retiform purpura with overlying necrosis subsequently developed over the course of a week following presentation (Figure 1). A skin biopsy showed fibrin thrombi and congestion of small- and medium-sized blood vessels, consistent with vasculopathy (Figure 2). Urinalysis revealed hematuria and proteinuria. A renal biopsy performed due to a continually elevated serum creatinine level revealed glomerulonephritis with numerous IgG1 lambda–restricted glomerular capillary hyaline thrombi, compatible with a lymphoproliferative disorder–associated type I cryoglobulinemia. A serum cryoglobulin immunofixation test confirmed type I cryoglobulinemia involving monoclonal IgG lambda. The combination of cutaneous, renal, and hematologic findings was consistent with type I cryoglobulinemia. A subsequent bone marrow biopsy demonstrated a CD20+ lambda–restricted plasma cell neoplasm. Initial treatment with high-dose corticosteroids followed by targeted treatment of the underlying hematologic condition with bortezomib, rituximab, and dexamethasone improved the skin disease.

Cryoglobulins are abnormal immunoglobulins that precipitate at temperatures below 37 °C. The persistent presence of cryoglobulins in the serum is termed cryoglobulinemia.¹ Type I cryoglobulinemia is distinguished from mixed cryoglobulinemia—types II and III—by the presence of a single monoclonal immunoglobulin, typically IgM or IgG. It is associated with lymphoproliferative disorders, most commonly monoclonal gammopathy of undetermined significance and B-cell malignancies such as Waldenström macroglobulinemia, multiple myeloma, or chronic lymphocytic leukemia. Histopathology shows occlusion of small vessel lumina with homogenous eosinophilic material containing the monoclonal cryoprecipitate.² Disease manifestations are caused by small vessel occlusion, which leads to ischemia and tissue damage.

Retiform purpura, livedo reticularis/racemosa, and necrosis leading to ulcers are the most common cutaneous clinical findings. Extracutaneous signs include peripheral neuropathy, arthralgia, Raynaud phenomenon, and acrocyanosis. Renal involvement, most commonly glomerulonephritis with associated proteinuria, is noted in 14% to 20% of cases.^3,4 An elevated cryocrit can lead to symptoms of hyperviscosity syndrome.²

Treatment is difficult and primarily is focused on addressing the underlying hematologic condition, which is responsible for synthesis of the cryoglobulin. Decreasing cryoglobulin production leads to decreased occlusion of blood vessels, thus alleviating the ischemia and skin damage. Monoclonal gammopathy of undetermined significance–related type I cryoglobulinemia initially is treated with corticosteroids followed by rituximab if a CD20+ B-cell clone is identified.² Bortezomib is recommended for cases associated with Waldenström macroglobulinemia and cases associated with multiple myeloma with concurrent renal failure. In patients with neuropathy, a lenalidomide-based treatment can be employed. Patients should be instructed to keep extremities warm.² Diabetic foot care guidelines should be followed to prevent wound complications. The differential diagnosis for type I cryoglobulinemia includes other causes of retiform purpura–like angioinvasive fungal infection, antiphospholipid antibody syndrome, calciphylaxis, and livedoid vasculopathy.⁵ Angioinvasive fungal infections are caused by Candida, Aspergillus, and Mucorales species, as well as other hyaline molds. They typically occur in immunocompromised patients and invade the blood vessels via direct inoculation or dissemination.⁶ Patients present with retiform purpura but typically will be acutely ill with fevers and vital sign abnormalities. Histopathology with special stains often will identify the fungal organisms in the dermis or inside blood vessel walls with vessel wall destruction and hemorrhage.⁷ Accurate diagnosis is essential to selecting appropriate antifungal agents. If angioinvasive fungal infection is clinically suspected, treatment should begin before culture and histopathologic data are available.⁷

Antiphospholipid antibody syndrome is an autoimmune thrombophilia that can occur as primary disease or in association with other autoimmune conditions, most commonly systemic lupus erythematosus. Diagnosis requires the presence of antiphospholipid antibodies, such as lupus anticoagulant, anticardiolipin antibody, anti–β2-glycoprotein-1 antibody, with arterial or venous thrombosis and/or recurrent pregnancy loss. Paraproteinemia is not seen. The most common cutaneous finding is livedo reticularis, with livedo racemosa being a more distinctive finding.8 Small vessel thrombosis is seen histopathologically. Treatment includes antiplatelet and anticoagulant medications. Patients with refractory disease may benefit from additional therapy with hydroxychloroquine or intravenous immunoglobulins.⁸

Calciphylaxis is a rare depositional vasculopathy that often occurs in patients with end-stage renal disease on dialysis. Patients present with painful and poor-healing skin lesions including indurated nodules, violaceous plaques, and retiform purpura that typically affect areas of high adiposity such as the thighs, abdomen, and buttocks.⁹ Ulceration and superimposed infections are common complications. Histopathologically, small dermal and subcutaneous vessels demonstrate calcification, microthrombosis, and fibrointimal hyperplasia.⁹ Wound management is critically important in patients with calciphylaxis. Treatment with intravenous sodium thiosulfate is typical, but prognosis remains poor. Although livedoid vasculopathy may present with retiform purpura in the ankles, paraproteinemia is not seen and patients frequently present with punched-out ulcerations that tend to heal into atrophie blanche.¹⁰ Livedoid vasculopathy has been associated with underlying hypercoagulable states, connective tissue diseases, and chronic venous hypertension. Hypercoagulability and endothelial cell damage contribute to the formation of fibrin thrombi in the superficial dermal blood vessels. Histopathology demonstrates thickening of vessel walls and intraluminal hyaline thrombi. Successful treatment in most cases is achieved with anticoagulation therapy, typically rivaroxaban, especially in patients with underlying hypercoagulability. Antiplatelet therapy also may be considered, while anabolic agents have been shown to be helpful in patients with connective tissue disease.¹⁰

The Diagnosis: Type I Cryoglobulinemia

Retiform purpura with overlying necrosis subsequently developed over the course of a week following presentation (Figure 1). A skin biopsy showed fibrin thrombi and congestion of small- and medium-sized blood vessels, consistent with vasculopathy (Figure 2). Urinalysis revealed hematuria and proteinuria. A renal biopsy performed due to a continually elevated serum creatinine level revealed glomerulonephritis with numerous IgG1 lambda–restricted glomerular capillary hyaline thrombi, compatible with a lymphoproliferative disorder–associated type I cryoglobulinemia. A serum cryoglobulin immunofixation test confirmed type I cryoglobulinemia involving monoclonal IgG lambda. The combination of cutaneous, renal, and hematologic findings was consistent with type I cryoglobulinemia. A subsequent bone marrow biopsy demonstrated a CD20+ lambda–restricted plasma cell neoplasm. Initial treatment with high-dose corticosteroids followed by targeted treatment of the underlying hematologic condition with bortezomib, rituximab, and dexamethasone improved the skin disease.

Cryoglobulins are abnormal immunoglobulins that precipitate at temperatures below 37 °C. The persistent presence of cryoglobulins in the serum is termed cryoglobulinemia.¹ Type I cryoglobulinemia is distinguished from mixed cryoglobulinemia—types II and III—by the presence of a single monoclonal immunoglobulin, typically IgM or IgG. It is associated with lymphoproliferative disorders, most commonly monoclonal gammopathy of undetermined significance and B-cell malignancies such as Waldenström macroglobulinemia, multiple myeloma, or chronic lymphocytic leukemia. Histopathology shows occlusion of small vessel lumina with homogenous eosinophilic material containing the monoclonal cryoprecipitate.² Disease manifestations are caused by small vessel occlusion, which leads to ischemia and tissue damage.

Retiform purpura, livedo reticularis/racemosa, and necrosis leading to ulcers are the most common cutaneous clinical findings. Extracutaneous signs include peripheral neuropathy, arthralgia, Raynaud phenomenon, and acrocyanosis. Renal involvement, most commonly glomerulonephritis with associated proteinuria, is noted in 14% to 20% of cases.^3,4 An elevated cryocrit can lead to symptoms of hyperviscosity syndrome.²

Treatment is difficult and primarily is focused on addressing the underlying hematologic condition, which is responsible for synthesis of the cryoglobulin. Decreasing cryoglobulin production leads to decreased occlusion of blood vessels, thus alleviating the ischemia and skin damage. Monoclonal gammopathy of undetermined significance–related type I cryoglobulinemia initially is treated with corticosteroids followed by rituximab if a CD20+ B-cell clone is identified.² Bortezomib is recommended for cases associated with Waldenström macroglobulinemia and cases associated with multiple myeloma with concurrent renal failure. In patients with neuropathy, a lenalidomide-based treatment can be employed. Patients should be instructed to keep extremities warm.² Diabetic foot care guidelines should be followed to prevent wound complications. The differential diagnosis for type I cryoglobulinemia includes other causes of retiform purpura–like angioinvasive fungal infection, antiphospholipid antibody syndrome, calciphylaxis, and livedoid vasculopathy.⁵ Angioinvasive fungal infections are caused by Candida, Aspergillus, and Mucorales species, as well as other hyaline molds. They typically occur in immunocompromised patients and invade the blood vessels via direct inoculation or dissemination.⁶ Patients present with retiform purpura but typically will be acutely ill with fevers and vital sign abnormalities. Histopathology with special stains often will identify the fungal organisms in the dermis or inside blood vessel walls with vessel wall destruction and hemorrhage.⁷ Accurate diagnosis is essential to selecting appropriate antifungal agents. If angioinvasive fungal infection is clinically suspected, treatment should begin before culture and histopathologic data are available.⁷

Antiphospholipid antibody syndrome is an autoimmune thrombophilia that can occur as primary disease or in association with other autoimmune conditions, most commonly systemic lupus erythematosus. Diagnosis requires the presence of antiphospholipid antibodies, such as lupus anticoagulant, anticardiolipin antibody, anti–β2-glycoprotein-1 antibody, with arterial or venous thrombosis and/or recurrent pregnancy loss. Paraproteinemia is not seen. The most common cutaneous finding is livedo reticularis, with livedo racemosa being a more distinctive finding.8 Small vessel thrombosis is seen histopathologically. Treatment includes antiplatelet and anticoagulant medications. Patients with refractory disease may benefit from additional therapy with hydroxychloroquine or intravenous immunoglobulins.⁸

Calciphylaxis is a rare depositional vasculopathy that often occurs in patients with end-stage renal disease on dialysis. Patients present with painful and poor-healing skin lesions including indurated nodules, violaceous plaques, and retiform purpura that typically affect areas of high adiposity such as the thighs, abdomen, and buttocks.⁹ Ulceration and superimposed infections are common complications. Histopathologically, small dermal and subcutaneous vessels demonstrate calcification, microthrombosis, and fibrointimal hyperplasia.⁹ Wound management is critically important in patients with calciphylaxis. Treatment with intravenous sodium thiosulfate is typical, but prognosis remains poor. Although livedoid vasculopathy may present with retiform purpura in the ankles, paraproteinemia is not seen and patients frequently present with punched-out ulcerations that tend to heal into atrophie blanche.¹⁰ Livedoid vasculopathy has been associated with underlying hypercoagulable states, connective tissue diseases, and chronic venous hypertension. Hypercoagulability and endothelial cell damage contribute to the formation of fibrin thrombi in the superficial dermal blood vessels. Histopathology demonstrates thickening of vessel walls and intraluminal hyaline thrombi. Successful treatment in most cases is achieved with anticoagulation therapy, typically rivaroxaban, especially in patients with underlying hypercoagulability. Antiplatelet therapy also may be considered, while anabolic agents have been shown to be helpful in patients with connective tissue disease.¹⁰

The Diagnosis: Type I Cryoglobulinemia

Retiform purpura with overlying necrosis subsequently developed over the course of a week following presentation (Figure 1). A skin biopsy showed fibrin thrombi and congestion of small- and medium-sized blood vessels, consistent with vasculopathy (Figure 2). Urinalysis revealed hematuria and proteinuria. A renal biopsy performed due to a continually elevated serum creatinine level revealed glomerulonephritis with numerous IgG1 lambda–restricted glomerular capillary hyaline thrombi, compatible with a lymphoproliferative disorder–associated type I cryoglobulinemia. A serum cryoglobulin immunofixation test confirmed type I cryoglobulinemia involving monoclonal IgG lambda. The combination of cutaneous, renal, and hematologic findings was consistent with type I cryoglobulinemia. A subsequent bone marrow biopsy demonstrated a CD20+ lambda–restricted plasma cell neoplasm. Initial treatment with high-dose corticosteroids followed by targeted treatment of the underlying hematologic condition with bortezomib, rituximab, and dexamethasone improved the skin disease.

Cryoglobulins are abnormal immunoglobulins that precipitate at temperatures below 37 °C. The persistent presence of cryoglobulins in the serum is termed cryoglobulinemia.¹ Type I cryoglobulinemia is distinguished from mixed cryoglobulinemia—types II and III—by the presence of a single monoclonal immunoglobulin, typically IgM or IgG. It is associated with lymphoproliferative disorders, most commonly monoclonal gammopathy of undetermined significance and B-cell malignancies such as Waldenström macroglobulinemia, multiple myeloma, or chronic lymphocytic leukemia. Histopathology shows occlusion of small vessel lumina with homogenous eosinophilic material containing the monoclonal cryoprecipitate.² Disease manifestations are caused by small vessel occlusion, which leads to ischemia and tissue damage.

Retiform purpura, livedo reticularis/racemosa, and necrosis leading to ulcers are the most common cutaneous clinical findings. Extracutaneous signs include peripheral neuropathy, arthralgia, Raynaud phenomenon, and acrocyanosis. Renal involvement, most commonly glomerulonephritis with associated proteinuria, is noted in 14% to 20% of cases.^3,4 An elevated cryocrit can lead to symptoms of hyperviscosity syndrome.²

Treatment is difficult and primarily is focused on addressing the underlying hematologic condition, which is responsible for synthesis of the cryoglobulin. Decreasing cryoglobulin production leads to decreased occlusion of blood vessels, thus alleviating the ischemia and skin damage. Monoclonal gammopathy of undetermined significance–related type I cryoglobulinemia initially is treated with corticosteroids followed by rituximab if a CD20+ B-cell clone is identified.² Bortezomib is recommended for cases associated with Waldenström macroglobulinemia and cases associated with multiple myeloma with concurrent renal failure. In patients with neuropathy, a lenalidomide-based treatment can be employed. Patients should be instructed to keep extremities warm.² Diabetic foot care guidelines should be followed to prevent wound complications. The differential diagnosis for type I cryoglobulinemia includes other causes of retiform purpura–like angioinvasive fungal infection, antiphospholipid antibody syndrome, calciphylaxis, and livedoid vasculopathy.⁵ Angioinvasive fungal infections are caused by Candida, Aspergillus, and Mucorales species, as well as other hyaline molds. They typically occur in immunocompromised patients and invade the blood vessels via direct inoculation or dissemination.⁶ Patients present with retiform purpura but typically will be acutely ill with fevers and vital sign abnormalities. Histopathology with special stains often will identify the fungal organisms in the dermis or inside blood vessel walls with vessel wall destruction and hemorrhage.⁷ Accurate diagnosis is essential to selecting appropriate antifungal agents. If angioinvasive fungal infection is clinically suspected, treatment should begin before culture and histopathologic data are available.⁷

Antiphospholipid antibody syndrome is an autoimmune thrombophilia that can occur as primary disease or in association with other autoimmune conditions, most commonly systemic lupus erythematosus. Diagnosis requires the presence of antiphospholipid antibodies, such as lupus anticoagulant, anticardiolipin antibody, anti–β2-glycoprotein-1 antibody, with arterial or venous thrombosis and/or recurrent pregnancy loss. Paraproteinemia is not seen. The most common cutaneous finding is livedo reticularis, with livedo racemosa being a more distinctive finding.8 Small vessel thrombosis is seen histopathologically. Treatment includes antiplatelet and anticoagulant medications. Patients with refractory disease may benefit from additional therapy with hydroxychloroquine or intravenous immunoglobulins.⁸

Calciphylaxis is a rare depositional vasculopathy that often occurs in patients with end-stage renal disease on dialysis. Patients present with painful and poor-healing skin lesions including indurated nodules, violaceous plaques, and retiform purpura that typically affect areas of high adiposity such as the thighs, abdomen, and buttocks.⁹ Ulceration and superimposed infections are common complications. Histopathologically, small dermal and subcutaneous vessels demonstrate calcification, microthrombosis, and fibrointimal hyperplasia.⁹ Wound management is critically important in patients with calciphylaxis. Treatment with intravenous sodium thiosulfate is typical, but prognosis remains poor. Although livedoid vasculopathy may present with retiform purpura in the ankles, paraproteinemia is not seen and patients frequently present with punched-out ulcerations that tend to heal into atrophie blanche.¹⁰ Livedoid vasculopathy has been associated with underlying hypercoagulable states, connective tissue diseases, and chronic venous hypertension. Hypercoagulability and endothelial cell damage contribute to the formation of fibrin thrombi in the superficial dermal blood vessels. Histopathology demonstrates thickening of vessel walls and intraluminal hyaline thrombi. Successful treatment in most cases is achieved with anticoagulation therapy, typically rivaroxaban, especially in patients with underlying hypercoagulability. Antiplatelet therapy also may be considered, while anabolic agents have been shown to be helpful in patients with connective tissue disease.¹⁰

THE COMPARISON

A Melasma on the face of a Hispanic woman, with hyperpigmentation on the cheeks, bridge of the nose, and upper lip.

B Melasma on the face of a Malaysian woman, with hyperpigmentation on the upper cheeks and bridge of the nose.

C Melasma on the face of an African woman, with hyperpigmentation on the upper cheeks and lateral to the eyes.

Photographs courtesy of Richard P. Usatine, MD.

Melasma (also known as chloasma) is a pigmentary disorder that causes chronic symmetric hyperpigmentation on the face. In patients with darker skin tones, centrofacial areas are affected.¹ Increased deposition of melanin distributed in the dermis leads to dermal melanosis. Newer research suggests that mast cell and keratinocyte interactions, altered gene regulation, neovascularization, and disruptions in the basement membrane cause melasma.² Patients present with epidermal or dermal melasma or a combination of both (mixed melasma).³ Wood lamp examination is helpful to distinguish between epidermal and dermal melasma. Dermal and mixed melasma can be difficult to treat and require multimodal treatments.

Epidemiology

Melasma commonly affects women aged 20 to 40 years,⁴ with a female to male ratio of 9:1.⁵ Potential triggers of melasma include hormones (eg, pregnancy, oral contraceptives, hormone replacement therapy) and exposure to UV light.^2,5 Melasma occurs in patients of all racial and ethnic backgrounds; however, the prevalence is higher in patients with darker skin tones.²

Key clinical features in people with darker skin tones

Melasma commonly manifests as symmetrically distributed, reticulated (lacy), dark brown to grayish brown patches on the cheeks, nose, forehead, upper lip, and chin in patients with darker skin tones.⁵ The pigment can be tan brown in patients with lighter skin tones. Given that postinflammatory hyperpigmentation and other pigmentary disorders can cause a similar appearance, a biopsy sometimes is needed to confirm the diagnosis, but melasma is diagnosed via physical examination in most patients. Melasma can be misdiagnosed as postinflammatory hyperpigmentation, solar lentigines, exogenous ochronosis, and Hori nevus.⁵

Worth noting

Prevention

• Daily sunscreen use is critical to prevent worsening of melasma. Sunscreen may not appear cosmetically elegant on darker skin tones, which creates a barrier to its use.⁶ Protection from both sunlight and visible light is necessary. Visible light, including light from light bulbs and device-emitted blue light, can worsen melasma. Iron oxides in tinted sunscreen offer protection from visible light.

• Physicians can recommend sunscreens that are more transparent or tinted for a better cosmetic match.

• Severe flares of melasma can occur with sun exposure despite good control with medications and laser modalities.

Treatment

• First-line therapies include topical hydroquinone 2% to 4%, tretinoin, azelaic acid, kojic acid, or ascorbic acid (vitamin C). A popular topical compound is a steroid, tretinoin, and hydroquinone.^1,5 Over-the-counter hydroquinone has been removed from the market due to safety concerns; however, it is still first line in the treatment of melasma. If hydroquinone is prescribed, treatment intervals of 6 to 8 weeks followed by a hydroquinone-free period is advised to reduce the risk for exogenous ochronosis (a paradoxical darkening of the skin).

• Chemical peels are second-line treatments that are effective for melasma. Improvement in epidermal melasma has been shown with chemical peels containing Jessner solution, salicylic acid, or α-hydroxy acid. Patients with dermal and mixed melasma have seen improvement with trichloroacetic acid 25% to 35% with or without Jessner solution.¹

• Cysteamine is a topical treatment created from the degradation of coenzyme A. It disrupts the synthesis of melanin to create a more even skin tone. It may be recommended in combination with sunscreen as a first-line or second-line topical therapy.

• Oral tranexamic acid is a third-line treatment that is an analogue for lysine. It decreases prostaglandin production, which leads to a lower number of tyrosine precursors available for the creation of melanin. Tranexamic acid has been shown to lighten the appearance of melasma.⁷ The most common and dangerous adverse effect of tranexamic acid is blood clots and this treatment should be avoided in those on combination (estrogen and progestin) contraceptives or those with a personal or family history of clotting disorders.⁸

• Fourth-line treatments such as lasers (performed by dermatologists) can destroy the deposition of pigment while avoiding destruction of epidermal keratinocytes.^1,9,10 They also are commonly employed in refractive melasma. The most common lasers are nonablative fractionated lasers and low-fluence Q-switched lasers. The Q-switched Nd:YAG and picosecond lasers are safe for treating melasma in darker skin tones. Ablative fractionated lasers such as CO₂ lasers and erbium:YAG lasers also have been used in the treatment of melasma; however, there is still an extremely high risk for postinflammatory dyspigmentation 1 to 2 months after the procedure.¹⁰

• Although there is still a risk for rebound hyperpigmentation after laser treatment, use of topical hydroquinone pretreatment may help decrease postoperative hyperpigmentation.^1,5 Patients who are treated with the incorrect laser or overtreated may develop postinflammatory hyperpigmentation, rebound hyperpigmentation, or hypopigmentation.

Health disparity highlight

Melasma, most common in patients with skin of color, is a common chronic pigmentation disorder that is cosmetically and psychologically burdensome,¹¹ leading to decreased quality of life, emotional functioning, and selfesteem.¹² Clinicians should counsel patients and work closely on long-term management. The treatment options for melasma are considered cosmetic and may be cost prohibitive for many to cover out-of-pocket. Topical treatments have been found to be the most cost-effective.¹³ Some compounding pharmacies and drug discount programs provide more affordable treatment pricing; however, some patients are still unable to afford these options.

THE COMPARISON

A Melasma on the face of a Hispanic woman, with hyperpigmentation on the cheeks, bridge of the nose, and upper lip.

B Melasma on the face of a Malaysian woman, with hyperpigmentation on the upper cheeks and bridge of the nose.

C Melasma on the face of an African woman, with hyperpigmentation on the upper cheeks and lateral to the eyes.

Photographs courtesy of Richard P. Usatine, MD.

Melasma (also known as chloasma) is a pigmentary disorder that causes chronic symmetric hyperpigmentation on the face. In patients with darker skin tones, centrofacial areas are affected.¹ Increased deposition of melanin distributed in the dermis leads to dermal melanosis. Newer research suggests that mast cell and keratinocyte interactions, altered gene regulation, neovascularization, and disruptions in the basement membrane cause melasma.² Patients present with epidermal or dermal melasma or a combination of both (mixed melasma).³ Wood lamp examination is helpful to distinguish between epidermal and dermal melasma. Dermal and mixed melasma can be difficult to treat and require multimodal treatments.

Epidemiology

Melasma commonly affects women aged 20 to 40 years,⁴ with a female to male ratio of 9:1.⁵ Potential triggers of melasma include hormones (eg, pregnancy, oral contraceptives, hormone replacement therapy) and exposure to UV light.^2,5 Melasma occurs in patients of all racial and ethnic backgrounds; however, the prevalence is higher in patients with darker skin tones.²

Key clinical features in people with darker skin tones

Melasma commonly manifests as symmetrically distributed, reticulated (lacy), dark brown to grayish brown patches on the cheeks, nose, forehead, upper lip, and chin in patients with darker skin tones.⁵ The pigment can be tan brown in patients with lighter skin tones. Given that postinflammatory hyperpigmentation and other pigmentary disorders can cause a similar appearance, a biopsy sometimes is needed to confirm the diagnosis, but melasma is diagnosed via physical examination in most patients. Melasma can be misdiagnosed as postinflammatory hyperpigmentation, solar lentigines, exogenous ochronosis, and Hori nevus.⁵

Worth noting

Prevention

• Daily sunscreen use is critical to prevent worsening of melasma. Sunscreen may not appear cosmetically elegant on darker skin tones, which creates a barrier to its use.⁶ Protection from both sunlight and visible light is necessary. Visible light, including light from light bulbs and device-emitted blue light, can worsen melasma. Iron oxides in tinted sunscreen offer protection from visible light.

• Physicians can recommend sunscreens that are more transparent or tinted for a better cosmetic match.

• Severe flares of melasma can occur with sun exposure despite good control with medications and laser modalities.

Treatment

• First-line therapies include topical hydroquinone 2% to 4%, tretinoin, azelaic acid, kojic acid, or ascorbic acid (vitamin C). A popular topical compound is a steroid, tretinoin, and hydroquinone.^1,5 Over-the-counter hydroquinone has been removed from the market due to safety concerns; however, it is still first line in the treatment of melasma. If hydroquinone is prescribed, treatment intervals of 6 to 8 weeks followed by a hydroquinone-free period is advised to reduce the risk for exogenous ochronosis (a paradoxical darkening of the skin).

• Chemical peels are second-line treatments that are effective for melasma. Improvement in epidermal melasma has been shown with chemical peels containing Jessner solution, salicylic acid, or α-hydroxy acid. Patients with dermal and mixed melasma have seen improvement with trichloroacetic acid 25% to 35% with or without Jessner solution.¹

• Cysteamine is a topical treatment created from the degradation of coenzyme A. It disrupts the synthesis of melanin to create a more even skin tone. It may be recommended in combination with sunscreen as a first-line or second-line topical therapy.

• Oral tranexamic acid is a third-line treatment that is an analogue for lysine. It decreases prostaglandin production, which leads to a lower number of tyrosine precursors available for the creation of melanin. Tranexamic acid has been shown to lighten the appearance of melasma.⁷ The most common and dangerous adverse effect of tranexamic acid is blood clots and this treatment should be avoided in those on combination (estrogen and progestin) contraceptives or those with a personal or family history of clotting disorders.⁸

• Fourth-line treatments such as lasers (performed by dermatologists) can destroy the deposition of pigment while avoiding destruction of epidermal keratinocytes.^1,9,10 They also are commonly employed in refractive melasma. The most common lasers are nonablative fractionated lasers and low-fluence Q-switched lasers. The Q-switched Nd:YAG and picosecond lasers are safe for treating melasma in darker skin tones. Ablative fractionated lasers such as CO₂ lasers and erbium:YAG lasers also have been used in the treatment of melasma; however, there is still an extremely high risk for postinflammatory dyspigmentation 1 to 2 months after the procedure.¹⁰

• Although there is still a risk for rebound hyperpigmentation after laser treatment, use of topical hydroquinone pretreatment may help decrease postoperative hyperpigmentation.^1,5 Patients who are treated with the incorrect laser or overtreated may develop postinflammatory hyperpigmentation, rebound hyperpigmentation, or hypopigmentation.

Health disparity highlight

Melasma, most common in patients with skin of color, is a common chronic pigmentation disorder that is cosmetically and psychologically burdensome,¹¹ leading to decreased quality of life, emotional functioning, and selfesteem.¹² Clinicians should counsel patients and work closely on long-term management. The treatment options for melasma are considered cosmetic and may be cost prohibitive for many to cover out-of-pocket. Topical treatments have been found to be the most cost-effective.¹³ Some compounding pharmacies and drug discount programs provide more affordable treatment pricing; however, some patients are still unable to afford these options.

THE COMPARISON

A Melasma on the face of a Hispanic woman, with hyperpigmentation on the cheeks, bridge of the nose, and upper lip.

B Melasma on the face of a Malaysian woman, with hyperpigmentation on the upper cheeks and bridge of the nose.

C Melasma on the face of an African woman, with hyperpigmentation on the upper cheeks and lateral to the eyes.

Photographs courtesy of Richard P. Usatine, MD.

Melasma (also known as chloasma) is a pigmentary disorder that causes chronic symmetric hyperpigmentation on the face. In patients with darker skin tones, centrofacial areas are affected.¹ Increased deposition of melanin distributed in the dermis leads to dermal melanosis. Newer research suggests that mast cell and keratinocyte interactions, altered gene regulation, neovascularization, and disruptions in the basement membrane cause melasma.² Patients present with epidermal or dermal melasma or a combination of both (mixed melasma).³ Wood lamp examination is helpful to distinguish between epidermal and dermal melasma. Dermal and mixed melasma can be difficult to treat and require multimodal treatments.

Epidemiology

Melasma commonly affects women aged 20 to 40 years,⁴ with a female to male ratio of 9:1.⁵ Potential triggers of melasma include hormones (eg, pregnancy, oral contraceptives, hormone replacement therapy) and exposure to UV light.^2,5 Melasma occurs in patients of all racial and ethnic backgrounds; however, the prevalence is higher in patients with darker skin tones.²

Key clinical features in people with darker skin tones

Melasma commonly manifests as symmetrically distributed, reticulated (lacy), dark brown to grayish brown patches on the cheeks, nose, forehead, upper lip, and chin in patients with darker skin tones.⁵ The pigment can be tan brown in patients with lighter skin tones. Given that postinflammatory hyperpigmentation and other pigmentary disorders can cause a similar appearance, a biopsy sometimes is needed to confirm the diagnosis, but melasma is diagnosed via physical examination in most patients. Melasma can be misdiagnosed as postinflammatory hyperpigmentation, solar lentigines, exogenous ochronosis, and Hori nevus.⁵

Worth noting

Prevention

• Daily sunscreen use is critical to prevent worsening of melasma. Sunscreen may not appear cosmetically elegant on darker skin tones, which creates a barrier to its use.⁶ Protection from both sunlight and visible light is necessary. Visible light, including light from light bulbs and device-emitted blue light, can worsen melasma. Iron oxides in tinted sunscreen offer protection from visible light.

• Physicians can recommend sunscreens that are more transparent or tinted for a better cosmetic match.

• Severe flares of melasma can occur with sun exposure despite good control with medications and laser modalities.

Treatment

• First-line therapies include topical hydroquinone 2% to 4%, tretinoin, azelaic acid, kojic acid, or ascorbic acid (vitamin C). A popular topical compound is a steroid, tretinoin, and hydroquinone.^1,5 Over-the-counter hydroquinone has been removed from the market due to safety concerns; however, it is still first line in the treatment of melasma. If hydroquinone is prescribed, treatment intervals of 6 to 8 weeks followed by a hydroquinone-free period is advised to reduce the risk for exogenous ochronosis (a paradoxical darkening of the skin).

• Chemical peels are second-line treatments that are effective for melasma. Improvement in epidermal melasma has been shown with chemical peels containing Jessner solution, salicylic acid, or α-hydroxy acid. Patients with dermal and mixed melasma have seen improvement with trichloroacetic acid 25% to 35% with or without Jessner solution.¹

• Cysteamine is a topical treatment created from the degradation of coenzyme A. It disrupts the synthesis of melanin to create a more even skin tone. It may be recommended in combination with sunscreen as a first-line or second-line topical therapy.

• Oral tranexamic acid is a third-line treatment that is an analogue for lysine. It decreases prostaglandin production, which leads to a lower number of tyrosine precursors available for the creation of melanin. Tranexamic acid has been shown to lighten the appearance of melasma.⁷ The most common and dangerous adverse effect of tranexamic acid is blood clots and this treatment should be avoided in those on combination (estrogen and progestin) contraceptives or those with a personal or family history of clotting disorders.⁸

• Fourth-line treatments such as lasers (performed by dermatologists) can destroy the deposition of pigment while avoiding destruction of epidermal keratinocytes.^1,9,10 They also are commonly employed in refractive melasma. The most common lasers are nonablative fractionated lasers and low-fluence Q-switched lasers. The Q-switched Nd:YAG and picosecond lasers are safe for treating melasma in darker skin tones. Ablative fractionated lasers such as CO₂ lasers and erbium:YAG lasers also have been used in the treatment of melasma; however, there is still an extremely high risk for postinflammatory dyspigmentation 1 to 2 months after the procedure.¹⁰

• Although there is still a risk for rebound hyperpigmentation after laser treatment, use of topical hydroquinone pretreatment may help decrease postoperative hyperpigmentation.^1,5 Patients who are treated with the incorrect laser or overtreated may develop postinflammatory hyperpigmentation, rebound hyperpigmentation, or hypopigmentation.

Health disparity highlight

Melasma, most common in patients with skin of color, is a common chronic pigmentation disorder that is cosmetically and psychologically burdensome,¹¹ leading to decreased quality of life, emotional functioning, and selfesteem.¹² Clinicians should counsel patients and work closely on long-term management. The treatment options for melasma are considered cosmetic and may be cost prohibitive for many to cover out-of-pocket. Topical treatments have been found to be the most cost-effective.¹³ Some compounding pharmacies and drug discount programs provide more affordable treatment pricing; however, some patients are still unable to afford these options.