Dermatopathology

The Diagnosis: Erythropoietic Protoporphyria 

Erythropoietic protoporphyria (EPP) is an autosomal-recessive photodermatosis that results from loss of activity of ferrochelatase, the last enzyme in the heme biosynthetic pathway.¹ Erythropoietic protoporphyria normally involves sun-exposed areas of the body. Skin that is exposed to sunlight develops intense burning and stinging pain followed by erythema, edema, crusting, and petechiae that develops into waxy scarring over time. In contrast to other porphyrias, blistering generally is not seen.² Accurate diagnosis often can be delayed by a decade or more following symptom onset due to the prominence of subjective pain as the presenting sign.  

The histologic appearance of EPP differs depending on the chronicity of lesions. Biopsies of acute lesions show vacuolization of epidermal cells with intercellular edema, vacuolization and cytolysis of endothelial cells in superficial blood vessels, and focal red blood cell extravasation.^3,4 A largely neutrophilic inflammatory infiltrate can be present.⁵ Hyaline cuffing develops over time in and around vessels in the papillary and superficial reticular dermis with notable sparing of adnexal structures. The perivascular deposits are strongly periodic acid-Schiff (PAS) positive and diastase resistant (Figure 1). Direct immunofluorescence shows mainly IgG and some IgM, fibrinogen, and C3 outlining characteristic donut-shaped blood vessels in the papillary dermis.⁶ The prominent thickness of the perivascular hyaline material depositions and the absence of subepidermal blistering can help differentiate EPP from porphyria cutanea tarda (PCT) and pseudoporphyria.^6,7 When the deposition is extensive and involves the surrounding dermis, EPP can mimic colloid milium. Additional histologic differential diagnoses of EPP include other dermal depositional diseases such as lipoid proteinosis and amyloidosis.  

Lipoid proteinosis is an autosomal-recessive multisystem genodermatosis caused by mutations in extracellular matrix gene 1, ECM1. The first clinical sign can be a hoarse cry in infancy due to infiltration of vocal cords.³ Development of papulonodular lesions along the eyelids can result in a string-of-beads appearance called moniliform blepharosis, which is pathognomonic for lipoid proteinosis.⁶ With chronicity, the involved skin can become yellow, waxy, and thickened, particularly in the flexures or areas of trauma. Histologically, the dermis in lipoid proteinosis becomes diffusely thickened due to deposition of PAS-positive eosinophilic hyaline material that stains weakly with Congo red and thioflavin T.⁶ Early lesions demonstrate pale pink, hyalinelike thickening of the papillary dermal capillaries. Chronic lesions reveal an acanthotic epidermis, occasional papillomatosis with overlying hyperkeratosis, and a thickened dermis where diffuse thick bundles of pink hyaline deposits are oriented perpendicularly to the dermoepidermal junction.^1,6 Lipoid proteinosis can be differentiated from EPP by the involvement of adnexal structures such as hair follicles, sebaceous glands, and arrector pili muscles (Figure 2), as opposed to EPP where adnexal structures are spared.¹ Additionally, depositions in lipoid proteinosis are centered around both superficial and deep vessels with an onion skin-like pattern, while EPP involves mainly superficial vessels with more mild and focal hyalinization.

Juvenile colloid milium (JCM) is a rare condition that presents before puberty with discrete, yellow-brown, translucent papules predominantly located on the cheeks and nose and around the mouth. A gelatinous material can be expressed after puncturing a lesion.⁶ Gingival deposits and ligneous conjunctivitis also can be present. On histopathology, JCM shows degeneration of epidermal keratinocytes that form colloid bodies within the superficial dermis following apoptosis.⁶ Hematoxylin and eosin staining shows amorphous, fissured, pale pink deposits completely filling and expanding the superficial to mid dermis with clefting and no inflammation (Figure 3). Spindle-shaped fibroblasts may be seen within the lines of colloid fissuring and dispersed throughout the deposits.¹ Histologically, JCM can be differentiated from EPP because deposits in EPP are distributed around and within superficial blood vessel walls, causing prominent vascular thickening not seen in JCM.⁶ The adult variant of colloid milium also can be distinguished from EPP by the presence of solar elastosis, which is absent in EPP due to a history of sun avoidance.^3,7  

Lichen amyloidosis presents with highly pruritic, red-brown, hyperkeratotic papules that commonly are found on the anterior lower legs and extensor forearms.¹ The calves, ankles, dorsal aspects of the feet, thighs, and trunk also may be affected. Excoriations, lichenification, and nodular prurigo-like lesions due to chronic scratching can be present.⁶ Lichen amyloidosis is characterized by large, pink, amorphous deposits in the papillary dermis with epidermal acanthosis, hypergranulosis, and hyperkeratosis (Figure 4).⁶ Perivascular deposits are not a feature of primary cutaneous localized amyloid lesions.⁶ The diagnosis can be confirmed with Congo red staining under polarized light, which classically demonstrates apple green birefringence.¹ For cases of amyloid that are not detected by Congo red or are not clear-cut, direct immunofluorescence and immunohistochemistry can be used as adjuncts for diagnosis. Amyloid deposits fluoresce positively for immunoglobulins or complements, particularly IgM and C3,⁸ and immunohistochemistry confirms the presence of keratin epitopes in deposits.⁹  

Porphyria cutanea tarda can appear histologically similar to EPP. Caterpillar bodies, or linearly arranged eosinophilic PAS-positive globules in the epidermis overlying subepidermal bullae, are a diagnostic histopathologic finding in both PCT and EPP but are seen in less than half of both cases.^7,10 Compared to EPP, the perivascular deposits in PCT typically are less pronounced and limited to the vessel wall with smaller hyaline cuffs (Figure 5).⁷ Additionally, solar elastosis can be seen in PCT lesions but not in EPP, as patients with PCT tend to be older and have increased cumulative sun damage.  

The Diagnosis: Erythropoietic Protoporphyria 

Erythropoietic protoporphyria (EPP) is an autosomal-recessive photodermatosis that results from loss of activity of ferrochelatase, the last enzyme in the heme biosynthetic pathway.¹ Erythropoietic protoporphyria normally involves sun-exposed areas of the body. Skin that is exposed to sunlight develops intense burning and stinging pain followed by erythema, edema, crusting, and petechiae that develops into waxy scarring over time. In contrast to other porphyrias, blistering generally is not seen.² Accurate diagnosis often can be delayed by a decade or more following symptom onset due to the prominence of subjective pain as the presenting sign.  

The histologic appearance of EPP differs depending on the chronicity of lesions. Biopsies of acute lesions show vacuolization of epidermal cells with intercellular edema, vacuolization and cytolysis of endothelial cells in superficial blood vessels, and focal red blood cell extravasation.^3,4 A largely neutrophilic inflammatory infiltrate can be present.⁵ Hyaline cuffing develops over time in and around vessels in the papillary and superficial reticular dermis with notable sparing of adnexal structures. The perivascular deposits are strongly periodic acid-Schiff (PAS) positive and diastase resistant (Figure 1). Direct immunofluorescence shows mainly IgG and some IgM, fibrinogen, and C3 outlining characteristic donut-shaped blood vessels in the papillary dermis.⁶ The prominent thickness of the perivascular hyaline material depositions and the absence of subepidermal blistering can help differentiate EPP from porphyria cutanea tarda (PCT) and pseudoporphyria.^6,7 When the deposition is extensive and involves the surrounding dermis, EPP can mimic colloid milium. Additional histologic differential diagnoses of EPP include other dermal depositional diseases such as lipoid proteinosis and amyloidosis.  

Lipoid proteinosis is an autosomal-recessive multisystem genodermatosis caused by mutations in extracellular matrix gene 1, ECM1. The first clinical sign can be a hoarse cry in infancy due to infiltration of vocal cords.³ Development of papulonodular lesions along the eyelids can result in a string-of-beads appearance called moniliform blepharosis, which is pathognomonic for lipoid proteinosis.⁶ With chronicity, the involved skin can become yellow, waxy, and thickened, particularly in the flexures or areas of trauma. Histologically, the dermis in lipoid proteinosis becomes diffusely thickened due to deposition of PAS-positive eosinophilic hyaline material that stains weakly with Congo red and thioflavin T.⁶ Early lesions demonstrate pale pink, hyalinelike thickening of the papillary dermal capillaries. Chronic lesions reveal an acanthotic epidermis, occasional papillomatosis with overlying hyperkeratosis, and a thickened dermis where diffuse thick bundles of pink hyaline deposits are oriented perpendicularly to the dermoepidermal junction.^1,6 Lipoid proteinosis can be differentiated from EPP by the involvement of adnexal structures such as hair follicles, sebaceous glands, and arrector pili muscles (Figure 2), as opposed to EPP where adnexal structures are spared.¹ Additionally, depositions in lipoid proteinosis are centered around both superficial and deep vessels with an onion skin-like pattern, while EPP involves mainly superficial vessels with more mild and focal hyalinization.

Juvenile colloid milium (JCM) is a rare condition that presents before puberty with discrete, yellow-brown, translucent papules predominantly located on the cheeks and nose and around the mouth. A gelatinous material can be expressed after puncturing a lesion.⁶ Gingival deposits and ligneous conjunctivitis also can be present. On histopathology, JCM shows degeneration of epidermal keratinocytes that form colloid bodies within the superficial dermis following apoptosis.⁶ Hematoxylin and eosin staining shows amorphous, fissured, pale pink deposits completely filling and expanding the superficial to mid dermis with clefting and no inflammation (Figure 3). Spindle-shaped fibroblasts may be seen within the lines of colloid fissuring and dispersed throughout the deposits.¹ Histologically, JCM can be differentiated from EPP because deposits in EPP are distributed around and within superficial blood vessel walls, causing prominent vascular thickening not seen in JCM.⁶ The adult variant of colloid milium also can be distinguished from EPP by the presence of solar elastosis, which is absent in EPP due to a history of sun avoidance.^3,7  

Lichen amyloidosis presents with highly pruritic, red-brown, hyperkeratotic papules that commonly are found on the anterior lower legs and extensor forearms.¹ The calves, ankles, dorsal aspects of the feet, thighs, and trunk also may be affected. Excoriations, lichenification, and nodular prurigo-like lesions due to chronic scratching can be present.⁶ Lichen amyloidosis is characterized by large, pink, amorphous deposits in the papillary dermis with epidermal acanthosis, hypergranulosis, and hyperkeratosis (Figure 4).⁶ Perivascular deposits are not a feature of primary cutaneous localized amyloid lesions.⁶ The diagnosis can be confirmed with Congo red staining under polarized light, which classically demonstrates apple green birefringence.¹ For cases of amyloid that are not detected by Congo red or are not clear-cut, direct immunofluorescence and immunohistochemistry can be used as adjuncts for diagnosis. Amyloid deposits fluoresce positively for immunoglobulins or complements, particularly IgM and C3,⁸ and immunohistochemistry confirms the presence of keratin epitopes in deposits.⁹  

Porphyria cutanea tarda can appear histologically similar to EPP. Caterpillar bodies, or linearly arranged eosinophilic PAS-positive globules in the epidermis overlying subepidermal bullae, are a diagnostic histopathologic finding in both PCT and EPP but are seen in less than half of both cases.^7,10 Compared to EPP, the perivascular deposits in PCT typically are less pronounced and limited to the vessel wall with smaller hyaline cuffs (Figure 5).⁷ Additionally, solar elastosis can be seen in PCT lesions but not in EPP, as patients with PCT tend to be older and have increased cumulative sun damage.  

The Diagnosis: Erythropoietic Protoporphyria 

Erythropoietic protoporphyria (EPP) is an autosomal-recessive photodermatosis that results from loss of activity of ferrochelatase, the last enzyme in the heme biosynthetic pathway.¹ Erythropoietic protoporphyria normally involves sun-exposed areas of the body. Skin that is exposed to sunlight develops intense burning and stinging pain followed by erythema, edema, crusting, and petechiae that develops into waxy scarring over time. In contrast to other porphyrias, blistering generally is not seen.² Accurate diagnosis often can be delayed by a decade or more following symptom onset due to the prominence of subjective pain as the presenting sign.  

The histologic appearance of EPP differs depending on the chronicity of lesions. Biopsies of acute lesions show vacuolization of epidermal cells with intercellular edema, vacuolization and cytolysis of endothelial cells in superficial blood vessels, and focal red blood cell extravasation.^3,4 A largely neutrophilic inflammatory infiltrate can be present.⁵ Hyaline cuffing develops over time in and around vessels in the papillary and superficial reticular dermis with notable sparing of adnexal structures. The perivascular deposits are strongly periodic acid-Schiff (PAS) positive and diastase resistant (Figure 1). Direct immunofluorescence shows mainly IgG and some IgM, fibrinogen, and C3 outlining characteristic donut-shaped blood vessels in the papillary dermis.⁶ The prominent thickness of the perivascular hyaline material depositions and the absence of subepidermal blistering can help differentiate EPP from porphyria cutanea tarda (PCT) and pseudoporphyria.^6,7 When the deposition is extensive and involves the surrounding dermis, EPP can mimic colloid milium. Additional histologic differential diagnoses of EPP include other dermal depositional diseases such as lipoid proteinosis and amyloidosis.  

Lipoid proteinosis is an autosomal-recessive multisystem genodermatosis caused by mutations in extracellular matrix gene 1, ECM1. The first clinical sign can be a hoarse cry in infancy due to infiltration of vocal cords.³ Development of papulonodular lesions along the eyelids can result in a string-of-beads appearance called moniliform blepharosis, which is pathognomonic for lipoid proteinosis.⁶ With chronicity, the involved skin can become yellow, waxy, and thickened, particularly in the flexures or areas of trauma. Histologically, the dermis in lipoid proteinosis becomes diffusely thickened due to deposition of PAS-positive eosinophilic hyaline material that stains weakly with Congo red and thioflavin T.⁶ Early lesions demonstrate pale pink, hyalinelike thickening of the papillary dermal capillaries. Chronic lesions reveal an acanthotic epidermis, occasional papillomatosis with overlying hyperkeratosis, and a thickened dermis where diffuse thick bundles of pink hyaline deposits are oriented perpendicularly to the dermoepidermal junction.^1,6 Lipoid proteinosis can be differentiated from EPP by the involvement of adnexal structures such as hair follicles, sebaceous glands, and arrector pili muscles (Figure 2), as opposed to EPP where adnexal structures are spared.¹ Additionally, depositions in lipoid proteinosis are centered around both superficial and deep vessels with an onion skin-like pattern, while EPP involves mainly superficial vessels with more mild and focal hyalinization.

Juvenile colloid milium (JCM) is a rare condition that presents before puberty with discrete, yellow-brown, translucent papules predominantly located on the cheeks and nose and around the mouth. A gelatinous material can be expressed after puncturing a lesion.⁶ Gingival deposits and ligneous conjunctivitis also can be present. On histopathology, JCM shows degeneration of epidermal keratinocytes that form colloid bodies within the superficial dermis following apoptosis.⁶ Hematoxylin and eosin staining shows amorphous, fissured, pale pink deposits completely filling and expanding the superficial to mid dermis with clefting and no inflammation (Figure 3). Spindle-shaped fibroblasts may be seen within the lines of colloid fissuring and dispersed throughout the deposits.¹ Histologically, JCM can be differentiated from EPP because deposits in EPP are distributed around and within superficial blood vessel walls, causing prominent vascular thickening not seen in JCM.⁶ The adult variant of colloid milium also can be distinguished from EPP by the presence of solar elastosis, which is absent in EPP due to a history of sun avoidance.^3,7  

Lichen amyloidosis presents with highly pruritic, red-brown, hyperkeratotic papules that commonly are found on the anterior lower legs and extensor forearms.¹ The calves, ankles, dorsal aspects of the feet, thighs, and trunk also may be affected. Excoriations, lichenification, and nodular prurigo-like lesions due to chronic scratching can be present.⁶ Lichen amyloidosis is characterized by large, pink, amorphous deposits in the papillary dermis with epidermal acanthosis, hypergranulosis, and hyperkeratosis (Figure 4).⁶ Perivascular deposits are not a feature of primary cutaneous localized amyloid lesions.⁶ The diagnosis can be confirmed with Congo red staining under polarized light, which classically demonstrates apple green birefringence.¹ For cases of amyloid that are not detected by Congo red or are not clear-cut, direct immunofluorescence and immunohistochemistry can be used as adjuncts for diagnosis. Amyloid deposits fluoresce positively for immunoglobulins or complements, particularly IgM and C3,⁸ and immunohistochemistry confirms the presence of keratin epitopes in deposits.⁹  

Porphyria cutanea tarda can appear histologically similar to EPP. Caterpillar bodies, or linearly arranged eosinophilic PAS-positive globules in the epidermis overlying subepidermal bullae, are a diagnostic histopathologic finding in both PCT and EPP but are seen in less than half of both cases.^7,10 Compared to EPP, the perivascular deposits in PCT typically are less pronounced and limited to the vessel wall with smaller hyaline cuffs (Figure 5).⁷ Additionally, solar elastosis can be seen in PCT lesions but not in EPP, as patients with PCT tend to be older and have increased cumulative sun damage.  

The Diagnosis: Scleredema Diabeticorum  

Histologically, scleredema is characterized by mucin deposition between collagen bundles in the deep dermis. Clinically, it is characterized by a progressive indurated plaque with associated stiffness of the involved area. It most commonly presents on the posterior aspect of the neck, though it can extend to involve the shoulders and upper torso.¹ Scleredema is divided into 3 subtypes based on clinical associations. Type 1 often is preceded by an infection, most commonly group A Streptococcus. This type occurs acutely and often resolves completely over a few months.² Type 2, which has progressive onset, is associated with monoclonal gammopathy.³ Type 3 is the most common type and is associated with diabetes mellitus. A study of 484 patients with type 2 diabetes mellitus demonstrated a prevalence of 2.5%.⁴ Although the exact pathogenesis has not been defined, it is hypothesized that irreversible glycosylation of collagen and alterations in collagenase activity may lead to accumulation of collagen and mucin in the dermis.⁵ Similar to type 2, type 3 scleredema appears subtly, progresses slowly, and tends to be chronic.^1,6 Scleredema is characterized by marked dermal thickening and enlarged collagen bundles separated by mucin deposition (Figure 1). Fibroblast proliferation is characteristically absent.¹ 

Clinically, tumid lupus erythematosus presents with erythematous edematous plaques on sun-exposed areas.⁷ Pretibial myxedema (PM) classically is associated with Graves disease; however, it can present in association with other types of thyroid dysfunction. Classically, PM presents on the pretibial regions as well-demarcated erythematous or hyperpigmented plaques.⁸ Similar to scleredema, histologic examination of tumid lupus erythematosus and PM reveals mucin deposition. Tumid lupus erythematosus also may demonstrate periadnexal and perivascular lymphocytic inflammation (Figure 2).⁷ The collagen bundles present in PM often are thin in comparison to scleredema (Figure 3).⁸ 

Scleroderma also presents with skin induration, erythema, and stiffening. However, unlike scleredema, scleroderma commonly involves the fingers, toes, and face. It presents with symptoms of Raynaud phenomenon, painful digital nonpitting edema, perioral skin tightening, mucocutaneous telangiectasia, and calcinosis cutis. Scleroderma also can involve organs such as the lungs, heart, kidneys, and gastrointestinal tract.⁹ Histologically, scleroderma is characterized by a compact dermis with closely packed collagen bundles. Other features of scleroderma can include perivascular mononuclear inflammatory cell infiltration, progressive atrophy of intradermal and perieccrine fat, and fibrosis (Figure 4).¹⁰ 

Scleromyxedema, also called papular mucinosis, is primary dermal mucinosis that often presents with waxy, dome-shaped papules that may coalesce into plaques. Similar to scleredema, scleromyxedema shows increased mucin deposition. However, scleromyxedema commonly is associated with fibroblast proliferation, which is characteristically absent in scleredema (Figure 5).¹¹

The Diagnosis: Scleredema Diabeticorum  

Histologically, scleredema is characterized by mucin deposition between collagen bundles in the deep dermis. Clinically, it is characterized by a progressive indurated plaque with associated stiffness of the involved area. It most commonly presents on the posterior aspect of the neck, though it can extend to involve the shoulders and upper torso.¹ Scleredema is divided into 3 subtypes based on clinical associations. Type 1 often is preceded by an infection, most commonly group A Streptococcus. This type occurs acutely and often resolves completely over a few months.² Type 2, which has progressive onset, is associated with monoclonal gammopathy.³ Type 3 is the most common type and is associated with diabetes mellitus. A study of 484 patients with type 2 diabetes mellitus demonstrated a prevalence of 2.5%.⁴ Although the exact pathogenesis has not been defined, it is hypothesized that irreversible glycosylation of collagen and alterations in collagenase activity may lead to accumulation of collagen and mucin in the dermis.⁵ Similar to type 2, type 3 scleredema appears subtly, progresses slowly, and tends to be chronic.^1,6 Scleredema is characterized by marked dermal thickening and enlarged collagen bundles separated by mucin deposition (Figure 1). Fibroblast proliferation is characteristically absent.¹ 

Clinically, tumid lupus erythematosus presents with erythematous edematous plaques on sun-exposed areas.⁷ Pretibial myxedema (PM) classically is associated with Graves disease; however, it can present in association with other types of thyroid dysfunction. Classically, PM presents on the pretibial regions as well-demarcated erythematous or hyperpigmented plaques.⁸ Similar to scleredema, histologic examination of tumid lupus erythematosus and PM reveals mucin deposition. Tumid lupus erythematosus also may demonstrate periadnexal and perivascular lymphocytic inflammation (Figure 2).⁷ The collagen bundles present in PM often are thin in comparison to scleredema (Figure 3).⁸ 

Scleroderma also presents with skin induration, erythema, and stiffening. However, unlike scleredema, scleroderma commonly involves the fingers, toes, and face. It presents with symptoms of Raynaud phenomenon, painful digital nonpitting edema, perioral skin tightening, mucocutaneous telangiectasia, and calcinosis cutis. Scleroderma also can involve organs such as the lungs, heart, kidneys, and gastrointestinal tract.⁹ Histologically, scleroderma is characterized by a compact dermis with closely packed collagen bundles. Other features of scleroderma can include perivascular mononuclear inflammatory cell infiltration, progressive atrophy of intradermal and perieccrine fat, and fibrosis (Figure 4).¹⁰ 

Scleromyxedema, also called papular mucinosis, is primary dermal mucinosis that often presents with waxy, dome-shaped papules that may coalesce into plaques. Similar to scleredema, scleromyxedema shows increased mucin deposition. However, scleromyxedema commonly is associated with fibroblast proliferation, which is characteristically absent in scleredema (Figure 5).¹¹

The Diagnosis: Scleredema Diabeticorum  

Histologically, scleredema is characterized by mucin deposition between collagen bundles in the deep dermis. Clinically, it is characterized by a progressive indurated plaque with associated stiffness of the involved area. It most commonly presents on the posterior aspect of the neck, though it can extend to involve the shoulders and upper torso.¹ Scleredema is divided into 3 subtypes based on clinical associations. Type 1 often is preceded by an infection, most commonly group A Streptococcus. This type occurs acutely and often resolves completely over a few months.² Type 2, which has progressive onset, is associated with monoclonal gammopathy.³ Type 3 is the most common type and is associated with diabetes mellitus. A study of 484 patients with type 2 diabetes mellitus demonstrated a prevalence of 2.5%.⁴ Although the exact pathogenesis has not been defined, it is hypothesized that irreversible glycosylation of collagen and alterations in collagenase activity may lead to accumulation of collagen and mucin in the dermis.⁵ Similar to type 2, type 3 scleredema appears subtly, progresses slowly, and tends to be chronic.^1,6 Scleredema is characterized by marked dermal thickening and enlarged collagen bundles separated by mucin deposition (Figure 1). Fibroblast proliferation is characteristically absent.¹ 

Clinically, tumid lupus erythematosus presents with erythematous edematous plaques on sun-exposed areas.⁷ Pretibial myxedema (PM) classically is associated with Graves disease; however, it can present in association with other types of thyroid dysfunction. Classically, PM presents on the pretibial regions as well-demarcated erythematous or hyperpigmented plaques.⁸ Similar to scleredema, histologic examination of tumid lupus erythematosus and PM reveals mucin deposition. Tumid lupus erythematosus also may demonstrate periadnexal and perivascular lymphocytic inflammation (Figure 2).⁷ The collagen bundles present in PM often are thin in comparison to scleredema (Figure 3).⁸ 

Scleroderma also presents with skin induration, erythema, and stiffening. However, unlike scleredema, scleroderma commonly involves the fingers, toes, and face. It presents with symptoms of Raynaud phenomenon, painful digital nonpitting edema, perioral skin tightening, mucocutaneous telangiectasia, and calcinosis cutis. Scleroderma also can involve organs such as the lungs, heart, kidneys, and gastrointestinal tract.⁹ Histologically, scleroderma is characterized by a compact dermis with closely packed collagen bundles. Other features of scleroderma can include perivascular mononuclear inflammatory cell infiltration, progressive atrophy of intradermal and perieccrine fat, and fibrosis (Figure 4).¹⁰ 

Scleromyxedema, also called papular mucinosis, is primary dermal mucinosis that often presents with waxy, dome-shaped papules that may coalesce into plaques. Similar to scleredema, scleromyxedema shows increased mucin deposition. However, scleromyxedema commonly is associated with fibroblast proliferation, which is characteristically absent in scleredema (Figure 5).¹¹

To the Editor:

A 46-year-old overweight woman presented with a rash in the axillae of 2 months’ duration. She did not report any additional symptoms such as pruritus or pain. She reported changing her deodorant recently from Secret Original to Secret Clinical Strength (both Procter & Gamble). Her medical history was remarkable for asthma and gastroesophageal reflux disease. Clinical examination revealed erythematous-brown, stuccolike, hyperkeratotic papules coalescing into plaques in recently shaved axillae, affecting the left axilla more than the right axilla (Figure 1). The clinical differential diagnosis included granular parakeratosis, intertrigo, Hailey-Hailey disease, Darier disease, pemphigus vegetans, confluent and reticulated papillomatosis, acanthosis nigricans, seborrheic keratoses, and irritant or allergic contact dermatitis. A punch biopsy revealed a marked compact parakeratotic horn with retention of keratohyalin granules (Figure 2). The subjacent epidermis showed some acanthosis and spongiosis with mild chronic inflammation of the dermal rim. Based on histopathology, granular parakeratosis was diagnosed.

At a subsequent visit 2 weeks later, we prescribed glycolic acid lotion 10% applied to the axillae twice daily, plus tretinoin gel 0.05% applied to the axillae each evening. She reported clearing after 1 week of therapy. She also had changed her deodorant from Secret Clinical Strength back to the usual Secret Original. The patient discontinued topical treatment after clearing of the lesions. Three weeks later, clinical examination revealed postinflammatory hyperpigmentation in the axillae, and the prior lesions had resolved (Figure 3).

The cause is unknown but possibly related to irritation from rubbing, occlusion, sweating, or deodorants.^5,7 Cases indicate a link to obesity. Hypotheses as to the etiology include the disruption of cornification. Normally, filaggrin maintains the keratohyaline granules in the stratum corneum during cornification. Therefore, the retention of keratohyaline granules in granular parakeratosis may be due to a defect in processing profilaggrin to filaggrin, which has been proposed based on ultrastructural and immunohistochemical studies.⁸

The differential diagnosis includes granular parakeratosis, intertrigo (caused by seborrheic dermatitis, candidiasis, inverse psoriasis, or erythrasma), Hailey-Hailey disease, Darier disease, pemphigus vegetans, confluent and reticulated papillomatosis, and irritant or allergic contact dermatitis. The papules may resemble seborrheic keratoses, while the plaques can be mistaken for acanthosis nigricans.

Therapeutic success has been reported with topical corticosteroids, vitamin D analogues, topical or oral retinoids, ammonium lactate, calcineurin inhibitors, topical or oral antifungals, cryotherapy, and botulinum toxin injections.^3,9-11 In addition, parakeratosis has decreased in biopsies from psoriatic patients after acitretin, methotrexate, and phototherapy, which may be alternative treatments for unusually difficult or recalcitrant cases of granular parakeratosis. To minimize side effects and resolve the papules quickly, we combined 2 synergistic agents—glycolic acid and tretinoin—each with different mechanisms of action, and we observed excellent clinical response.

Granular parakeratosis is possibly related to a combination of topical products that potentiate irritation, rubbing, and occlusion of sweat. Multiple treatment modalities likely contribute to clearing, the most important being removal of any triggering topical products. Our patient’s change in deodorant may have been the inciting factor for the disease. Withdrawal of the Secret Clinical Strength deodorant prompted clearing, though topical retinoid and glycolic acid acted as facilitating therapies for timely results. A thorough history, as highlighted by this case, may help pinpoint etiologic factors. By identifying a seemingly innocuous change in hygienic routine, we were able to minimize the need for ongoing therapy.

To the Editor:

A 46-year-old overweight woman presented with a rash in the axillae of 2 months’ duration. She did not report any additional symptoms such as pruritus or pain. She reported changing her deodorant recently from Secret Original to Secret Clinical Strength (both Procter & Gamble). Her medical history was remarkable for asthma and gastroesophageal reflux disease. Clinical examination revealed erythematous-brown, stuccolike, hyperkeratotic papules coalescing into plaques in recently shaved axillae, affecting the left axilla more than the right axilla (Figure 1). The clinical differential diagnosis included granular parakeratosis, intertrigo, Hailey-Hailey disease, Darier disease, pemphigus vegetans, confluent and reticulated papillomatosis, acanthosis nigricans, seborrheic keratoses, and irritant or allergic contact dermatitis. A punch biopsy revealed a marked compact parakeratotic horn with retention of keratohyalin granules (Figure 2). The subjacent epidermis showed some acanthosis and spongiosis with mild chronic inflammation of the dermal rim. Based on histopathology, granular parakeratosis was diagnosed.

At a subsequent visit 2 weeks later, we prescribed glycolic acid lotion 10% applied to the axillae twice daily, plus tretinoin gel 0.05% applied to the axillae each evening. She reported clearing after 1 week of therapy. She also had changed her deodorant from Secret Clinical Strength back to the usual Secret Original. The patient discontinued topical treatment after clearing of the lesions. Three weeks later, clinical examination revealed postinflammatory hyperpigmentation in the axillae, and the prior lesions had resolved (Figure 3).

The cause is unknown but possibly related to irritation from rubbing, occlusion, sweating, or deodorants.^5,7 Cases indicate a link to obesity. Hypotheses as to the etiology include the disruption of cornification. Normally, filaggrin maintains the keratohyaline granules in the stratum corneum during cornification. Therefore, the retention of keratohyaline granules in granular parakeratosis may be due to a defect in processing profilaggrin to filaggrin, which has been proposed based on ultrastructural and immunohistochemical studies.⁸

The differential diagnosis includes granular parakeratosis, intertrigo (caused by seborrheic dermatitis, candidiasis, inverse psoriasis, or erythrasma), Hailey-Hailey disease, Darier disease, pemphigus vegetans, confluent and reticulated papillomatosis, and irritant or allergic contact dermatitis. The papules may resemble seborrheic keratoses, while the plaques can be mistaken for acanthosis nigricans.

Therapeutic success has been reported with topical corticosteroids, vitamin D analogues, topical or oral retinoids, ammonium lactate, calcineurin inhibitors, topical or oral antifungals, cryotherapy, and botulinum toxin injections.^3,9-11 In addition, parakeratosis has decreased in biopsies from psoriatic patients after acitretin, methotrexate, and phototherapy, which may be alternative treatments for unusually difficult or recalcitrant cases of granular parakeratosis. To minimize side effects and resolve the papules quickly, we combined 2 synergistic agents—glycolic acid and tretinoin—each with different mechanisms of action, and we observed excellent clinical response.

Granular parakeratosis is possibly related to a combination of topical products that potentiate irritation, rubbing, and occlusion of sweat. Multiple treatment modalities likely contribute to clearing, the most important being removal of any triggering topical products. Our patient’s change in deodorant may have been the inciting factor for the disease. Withdrawal of the Secret Clinical Strength deodorant prompted clearing, though topical retinoid and glycolic acid acted as facilitating therapies for timely results. A thorough history, as highlighted by this case, may help pinpoint etiologic factors. By identifying a seemingly innocuous change in hygienic routine, we were able to minimize the need for ongoing therapy.

To the Editor:

A 46-year-old overweight woman presented with a rash in the axillae of 2 months’ duration. She did not report any additional symptoms such as pruritus or pain. She reported changing her deodorant recently from Secret Original to Secret Clinical Strength (both Procter & Gamble). Her medical history was remarkable for asthma and gastroesophageal reflux disease. Clinical examination revealed erythematous-brown, stuccolike, hyperkeratotic papules coalescing into plaques in recently shaved axillae, affecting the left axilla more than the right axilla (Figure 1). The clinical differential diagnosis included granular parakeratosis, intertrigo, Hailey-Hailey disease, Darier disease, pemphigus vegetans, confluent and reticulated papillomatosis, acanthosis nigricans, seborrheic keratoses, and irritant or allergic contact dermatitis. A punch biopsy revealed a marked compact parakeratotic horn with retention of keratohyalin granules (Figure 2). The subjacent epidermis showed some acanthosis and spongiosis with mild chronic inflammation of the dermal rim. Based on histopathology, granular parakeratosis was diagnosed.

At a subsequent visit 2 weeks later, we prescribed glycolic acid lotion 10% applied to the axillae twice daily, plus tretinoin gel 0.05% applied to the axillae each evening. She reported clearing after 1 week of therapy. She also had changed her deodorant from Secret Clinical Strength back to the usual Secret Original. The patient discontinued topical treatment after clearing of the lesions. Three weeks later, clinical examination revealed postinflammatory hyperpigmentation in the axillae, and the prior lesions had resolved (Figure 3).

The cause is unknown but possibly related to irritation from rubbing, occlusion, sweating, or deodorants.^5,7 Cases indicate a link to obesity. Hypotheses as to the etiology include the disruption of cornification. Normally, filaggrin maintains the keratohyaline granules in the stratum corneum during cornification. Therefore, the retention of keratohyaline granules in granular parakeratosis may be due to a defect in processing profilaggrin to filaggrin, which has been proposed based on ultrastructural and immunohistochemical studies.⁸

The differential diagnosis includes granular parakeratosis, intertrigo (caused by seborrheic dermatitis, candidiasis, inverse psoriasis, or erythrasma), Hailey-Hailey disease, Darier disease, pemphigus vegetans, confluent and reticulated papillomatosis, and irritant or allergic contact dermatitis. The papules may resemble seborrheic keratoses, while the plaques can be mistaken for acanthosis nigricans.

Therapeutic success has been reported with topical corticosteroids, vitamin D analogues, topical or oral retinoids, ammonium lactate, calcineurin inhibitors, topical or oral antifungals, cryotherapy, and botulinum toxin injections.^3,9-11 In addition, parakeratosis has decreased in biopsies from psoriatic patients after acitretin, methotrexate, and phototherapy, which may be alternative treatments for unusually difficult or recalcitrant cases of granular parakeratosis. To minimize side effects and resolve the papules quickly, we combined 2 synergistic agents—glycolic acid and tretinoin—each with different mechanisms of action, and we observed excellent clinical response.

Granular parakeratosis is possibly related to a combination of topical products that potentiate irritation, rubbing, and occlusion of sweat. Multiple treatment modalities likely contribute to clearing, the most important being removal of any triggering topical products. Our patient’s change in deodorant may have been the inciting factor for the disease. Withdrawal of the Secret Clinical Strength deodorant prompted clearing, though topical retinoid and glycolic acid acted as facilitating therapies for timely results. A thorough history, as highlighted by this case, may help pinpoint etiologic factors. By identifying a seemingly innocuous change in hygienic routine, we were able to minimize the need for ongoing therapy.

There are at least five dermatologic patterns in patients who are suspected or confirmed of having COVID-19, and the knowledge base continues to evolve, according to Christine Ko, MD.

“Things are very fluid,” Dr. Ko, professor of dermatology and pathology at Yale University, New Haven, Conn., said during the virtual annual meeting of the American Academy of Dermatology. “New studies are coming out daily. Due to the need for rapid dissemination, a lot of the studies are case reports, but there are some nice case series. Another caveat for the literature is that a lot of these cases were not necessarily confirmed with testing for SARS-CoV-2, but some were.”

Dr. Ko framed her remarks largely on a case collection survey of images and clinical data from 375 patients in Spain with suspected or confirmed COVID-19 that was published online April 29, 2020, in the British Journal of Dermatology (doi: 10.1111/bjd.19163). Cutaneous manifestations included early vesicular eruptions mainly on the trunk or limbs (9%), maculopapular (47%) to urticarial lesions (19%) mainly on the trunk, and acral areas of erythema sometimes with vesicles or erosion (perniosis-like) (19%) that seemed to be a later manifestation of COVID-19. Retiform purpura or necrosis (6%) was most concerning in terms of skin disease, with an associated with a mortality of 10%.

On histology, the early vesicular eruptions are typically marked by dyskeratotic keratinocytes, Dr. Ko said, while urticarial lesions are characterized by a mixed dermal infiltrate; maculopapular lesions were a broad category. “There are some case reports that show spongiotic dermatitis or parakeratosis with a lymphocytic infiltrate,” she said. “A caveat to keep in mind is that, although these patients may definitely have COVID-19 and be confirmed to have it by testing, hypersensitivity reactions may be due to the multiple medications they’re on.”

Patients can develop a spectrum of lesions that are suggestive of vascular damage or occlusion, Dr. Ko continued. Livedoid lesions may remain static and not eventuate into necrosis or purpura but will self-resolve. Purpuric lesions and acral gangrene have been described, and these lesions correspond to vascular occlusion on biopsy.

A later manifestation are the so-called “COVID toes” with a superficial and deep lymphocytic infiltrate, as published June 1, 2020, in JAAD Case Reports: (doi: 10.1016/j.jdcr.2020.04.011).

“There are patients in the literature that have slightly different pathology, with lymphocytic inflammation as well as occlusion of vessels,” Dr. Ko said. A paper published June 20, 2020, in the British Journal of Dermatology used immunohistochemical staining against the SARS-CoV-2 spike protein, and biopsies of “COVID toes” had positive staining of endothelial cells, supporting the notion that “COVID toes” are a direct manifestation of viral infection (doi: 10.1111/bjd.19327).

“There’s a lot that we still don’t know, and some patterns are going to be outliers,” Dr. Ko concluded. “[As for] determining which skin manifestations are directly from coronavirus infection within the skin, more study is needed and likely time will tell.” She reported having no financial disclosures relevant to her talk.

[email protected]

There are at least five dermatologic patterns in patients who are suspected or confirmed of having COVID-19, and the knowledge base continues to evolve, according to Christine Ko, MD.

“Things are very fluid,” Dr. Ko, professor of dermatology and pathology at Yale University, New Haven, Conn., said during the virtual annual meeting of the American Academy of Dermatology. “New studies are coming out daily. Due to the need for rapid dissemination, a lot of the studies are case reports, but there are some nice case series. Another caveat for the literature is that a lot of these cases were not necessarily confirmed with testing for SARS-CoV-2, but some were.”

Dr. Ko framed her remarks largely on a case collection survey of images and clinical data from 375 patients in Spain with suspected or confirmed COVID-19 that was published online April 29, 2020, in the British Journal of Dermatology (doi: 10.1111/bjd.19163). Cutaneous manifestations included early vesicular eruptions mainly on the trunk or limbs (9%), maculopapular (47%) to urticarial lesions (19%) mainly on the trunk, and acral areas of erythema sometimes with vesicles or erosion (perniosis-like) (19%) that seemed to be a later manifestation of COVID-19. Retiform purpura or necrosis (6%) was most concerning in terms of skin disease, with an associated with a mortality of 10%.

On histology, the early vesicular eruptions are typically marked by dyskeratotic keratinocytes, Dr. Ko said, while urticarial lesions are characterized by a mixed dermal infiltrate; maculopapular lesions were a broad category. “There are some case reports that show spongiotic dermatitis or parakeratosis with a lymphocytic infiltrate,” she said. “A caveat to keep in mind is that, although these patients may definitely have COVID-19 and be confirmed to have it by testing, hypersensitivity reactions may be due to the multiple medications they’re on.”

Patients can develop a spectrum of lesions that are suggestive of vascular damage or occlusion, Dr. Ko continued. Livedoid lesions may remain static and not eventuate into necrosis or purpura but will self-resolve. Purpuric lesions and acral gangrene have been described, and these lesions correspond to vascular occlusion on biopsy.

A later manifestation are the so-called “COVID toes” with a superficial and deep lymphocytic infiltrate, as published June 1, 2020, in JAAD Case Reports: (doi: 10.1016/j.jdcr.2020.04.011).

“There are patients in the literature that have slightly different pathology, with lymphocytic inflammation as well as occlusion of vessels,” Dr. Ko said. A paper published June 20, 2020, in the British Journal of Dermatology used immunohistochemical staining against the SARS-CoV-2 spike protein, and biopsies of “COVID toes” had positive staining of endothelial cells, supporting the notion that “COVID toes” are a direct manifestation of viral infection (doi: 10.1111/bjd.19327).

“There’s a lot that we still don’t know, and some patterns are going to be outliers,” Dr. Ko concluded. “[As for] determining which skin manifestations are directly from coronavirus infection within the skin, more study is needed and likely time will tell.” She reported having no financial disclosures relevant to her talk.

[email protected]

There are at least five dermatologic patterns in patients who are suspected or confirmed of having COVID-19, and the knowledge base continues to evolve, according to Christine Ko, MD.

“Things are very fluid,” Dr. Ko, professor of dermatology and pathology at Yale University, New Haven, Conn., said during the virtual annual meeting of the American Academy of Dermatology. “New studies are coming out daily. Due to the need for rapid dissemination, a lot of the studies are case reports, but there are some nice case series. Another caveat for the literature is that a lot of these cases were not necessarily confirmed with testing for SARS-CoV-2, but some were.”

Dr. Ko framed her remarks largely on a case collection survey of images and clinical data from 375 patients in Spain with suspected or confirmed COVID-19 that was published online April 29, 2020, in the British Journal of Dermatology (doi: 10.1111/bjd.19163). Cutaneous manifestations included early vesicular eruptions mainly on the trunk or limbs (9%), maculopapular (47%) to urticarial lesions (19%) mainly on the trunk, and acral areas of erythema sometimes with vesicles or erosion (perniosis-like) (19%) that seemed to be a later manifestation of COVID-19. Retiform purpura or necrosis (6%) was most concerning in terms of skin disease, with an associated with a mortality of 10%.

On histology, the early vesicular eruptions are typically marked by dyskeratotic keratinocytes, Dr. Ko said, while urticarial lesions are characterized by a mixed dermal infiltrate; maculopapular lesions were a broad category. “There are some case reports that show spongiotic dermatitis or parakeratosis with a lymphocytic infiltrate,” she said. “A caveat to keep in mind is that, although these patients may definitely have COVID-19 and be confirmed to have it by testing, hypersensitivity reactions may be due to the multiple medications they’re on.”

Patients can develop a spectrum of lesions that are suggestive of vascular damage or occlusion, Dr. Ko continued. Livedoid lesions may remain static and not eventuate into necrosis or purpura but will self-resolve. Purpuric lesions and acral gangrene have been described, and these lesions correspond to vascular occlusion on biopsy.

A later manifestation are the so-called “COVID toes” with a superficial and deep lymphocytic infiltrate, as published June 1, 2020, in JAAD Case Reports: (doi: 10.1016/j.jdcr.2020.04.011).

“There are patients in the literature that have slightly different pathology, with lymphocytic inflammation as well as occlusion of vessels,” Dr. Ko said. A paper published June 20, 2020, in the British Journal of Dermatology used immunohistochemical staining against the SARS-CoV-2 spike protein, and biopsies of “COVID toes” had positive staining of endothelial cells, supporting the notion that “COVID toes” are a direct manifestation of viral infection (doi: 10.1111/bjd.19327).

“There’s a lot that we still don’t know, and some patterns are going to be outliers,” Dr. Ko concluded. “[As for] determining which skin manifestations are directly from coronavirus infection within the skin, more study is needed and likely time will tell.” She reported having no financial disclosures relevant to her talk.

[email protected]

The Diagnosis: Bullous Leukocytoclastic Vasculitis  

Histopathology with hematoxylin and eosin (H&E) stain showed a perivascular neutrophilic infiltrate, karyorrhexis, red blood cell extravasation, and fibrin deposition in the vessel wall (quiz images). Direct immunofluorescence (DIF) showed fibrin surrounding the vasculature, consistent with vasculitis. The clinical and histopathological evaluation supported the diagnosis of bullous leukocytoclastic vasculitis (LCV). The patient had a full LCV workup including antinuclear antibody, rheumatoid factor, hepatitis B and hepatitis C screening, erythrocyte sedimentation rate, C-reactive protein, and C3/C4/total complement level, which were all within reference range. The patient denied that she had taken any medications prior to the onset of the rash. She was started on a 12-day prednisone taper starting at 60 mg, and the rash resolved in 1 week.  

Although the incidence of LCV is estimated to be 30 cases per million individuals per year,¹ bullous LCV is a rarer entity with only a few cases reported in the literature.^2,3 As in our patient's case, up to 50% of LCV cases are idiopathic or the etiology cannot be determined despite laboratory workup and medication review. Other cases can be secondary to medication, infection, collagen vascular disease, or malignancy.³ Despite the exact pathogenesis of bullous LCV being unknown,⁴ it likely is related to a type III hypersensitivity reaction with immune complex deposition in postcapillary venules leading to endothelial injury, activation of the complement cascade, and development of intraepidermal or subepidermal blister formation depending on location of inflammation and edema.² Clinically, an intraepidermal split would be more flaccid, similar to pemphigus vulgaris, while a subepidermal split, as in our patient, would be taut bullae. The subepidermal split more commonly is seen in bullous LCV.²  

Leukocytoclastic vasculitis on H&E staining characteristically has a perivascular inflammatory infiltrate, neutrophilic fragments called leukocytoclasis, and blood extravasation.³ Extravasated blood presents clinically as petechiae. In this case, the petechiae helped distinguish this entity from the differential diagnosis. Furthermore, DIF would be helpful in distinguishing bullous diseases such as bullous pemphigoid (BP) and pemphigus vulgaris from LCV.² Direct immunofluorescence in bullous LCV would have fibrinogen surrounding the vasculature without C3 and IgG deposition (intraepidermal or subepidermal).  

Mild cases of LCV often resolve with supportive measures including elevation of the legs, ice packs applied to the affected area, and removal of the inciting drug or event.⁴ In the few cases reported in the literature, bullous LCV presented more diffusely than classic LCV with bullous lesions on the forearms and the lower extremities. Oral steroids are efficacious for extensive bullous LCV.⁴ 

The differential diagnosis of bullous LCV includes bullous diseases with subepidermal split including BP and linear IgA bullous dermatosis (LABD). Bullous pemphigoid is an autoimmune subepidermal blistering disease typically affecting patients older than 60 years.⁵ The pathogenesis of BP is related to development of autoantibodies directed against hemidesmosome components, bullous pemphigoid antigen (BPAG) 1 or BPAG2.⁵ Bullous pemphigoid presents clinically as widespread, generally pruritic, erythematous, urticarial plaques with bullae. Histologically, BP characteristically has a subepidermal split with superficial dermal edema and eosinophils at the dermoepidermal junction (Figure 1). Direct immunofluorescence confirms the diagnosis with IgG and C3 deposition in an n-serrated pattern at the dermoepidermal junction.⁶ Bullous pemphigoid can be distinguished from bullous LCV by the older age of presentation, DIF findings, and the absence of purpura.  

Linear IgA bullous dermatosis represents a rare subepidermal vesiculobullous disease occurring in patients in their 60s.⁷ Clinically, this entity presents as tense bullae often located on the periphery of an urticarial plaque, classically called the "string of pearls sign." Histologically, LABD also presents with subepidermal split; however, neutrophils are the predominant cell type vs eosinophils in BP (Figure 2).⁷ Direct immunofluorescence is specific with a linear deposition of IgA at the dermoepidermal junction. Linear IgA bullous dermatosis most commonly is induced by vancomycin. Unlike bullous LCV, the bullae of LABD have an annular peripheral pattern on an erythematous base and lack purpura.  

Stasis dermatitis is inflammation of the dermis due to venous insufficiency that often is present in the bilateral lower extremities. The disorder affects approximately 7% of adults older than 50 years, but it also can occur in younger patients.⁸ The pathophysiology of stasis dermatitis is caused by edema, which leads to extracellular fluid, plasma proteins, macrophages, and erythrocytes passing into the interstitial space. Patients with stasis dermatitis present with scaly erythematous papules and plaques or edematous blisters on the lower extremities. Diagnosis usually can be made clinically; however, a skin biopsy also can be helpful. Hematoxylin and eosin shows a pauci-inflammatory subepidermal bulla with fibrin (Figure 3).⁸ The overlying epidermis is intact. The dermis has cannon ball angiomatosis, red blood cell extravasation, and fibrosis typical of stasis dermatitis. Stasis dermatitis with bullae is cell poor and lacks the perivascular inflammatory infiltrate and neutrophilic fragments that often are present in LCV, making the 2 entities distinguishable. 

Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) lies on a spectrum of severe cutaneous drug reactions involving the skin and mucous membranes. Cutaneous involvement typically begins on the trunk and face and later can involve the palms and soles.⁹ Similar drugs have been implicated in bullous LCV and SJS/TEN, including nonsteroidal anti-inflammatory drugs and antibiotics. Histologically, SJS/TEN has full-thickness epidermal necrolysis, vacuolar interface, and keratinocyte apoptosis (Figure 4).⁹ The clinical presentation of sloughing of skin with positive Nikolsky sign, oral involvement, and H&E and DIF findings can help differentiate this entity from bullous LCV.  

The Diagnosis: Bullous Leukocytoclastic Vasculitis  

Histopathology with hematoxylin and eosin (H&E) stain showed a perivascular neutrophilic infiltrate, karyorrhexis, red blood cell extravasation, and fibrin deposition in the vessel wall (quiz images). Direct immunofluorescence (DIF) showed fibrin surrounding the vasculature, consistent with vasculitis. The clinical and histopathological evaluation supported the diagnosis of bullous leukocytoclastic vasculitis (LCV). The patient had a full LCV workup including antinuclear antibody, rheumatoid factor, hepatitis B and hepatitis C screening, erythrocyte sedimentation rate, C-reactive protein, and C3/C4/total complement level, which were all within reference range. The patient denied that she had taken any medications prior to the onset of the rash. She was started on a 12-day prednisone taper starting at 60 mg, and the rash resolved in 1 week.  

Although the incidence of LCV is estimated to be 30 cases per million individuals per year,¹ bullous LCV is a rarer entity with only a few cases reported in the literature.^2,3 As in our patient's case, up to 50% of LCV cases are idiopathic or the etiology cannot be determined despite laboratory workup and medication review. Other cases can be secondary to medication, infection, collagen vascular disease, or malignancy.³ Despite the exact pathogenesis of bullous LCV being unknown,⁴ it likely is related to a type III hypersensitivity reaction with immune complex deposition in postcapillary venules leading to endothelial injury, activation of the complement cascade, and development of intraepidermal or subepidermal blister formation depending on location of inflammation and edema.² Clinically, an intraepidermal split would be more flaccid, similar to pemphigus vulgaris, while a subepidermal split, as in our patient, would be taut bullae. The subepidermal split more commonly is seen in bullous LCV.²  

Leukocytoclastic vasculitis on H&E staining characteristically has a perivascular inflammatory infiltrate, neutrophilic fragments called leukocytoclasis, and blood extravasation.³ Extravasated blood presents clinically as petechiae. In this case, the petechiae helped distinguish this entity from the differential diagnosis. Furthermore, DIF would be helpful in distinguishing bullous diseases such as bullous pemphigoid (BP) and pemphigus vulgaris from LCV.² Direct immunofluorescence in bullous LCV would have fibrinogen surrounding the vasculature without C3 and IgG deposition (intraepidermal or subepidermal).  

Mild cases of LCV often resolve with supportive measures including elevation of the legs, ice packs applied to the affected area, and removal of the inciting drug or event.⁴ In the few cases reported in the literature, bullous LCV presented more diffusely than classic LCV with bullous lesions on the forearms and the lower extremities. Oral steroids are efficacious for extensive bullous LCV.⁴ 

The differential diagnosis of bullous LCV includes bullous diseases with subepidermal split including BP and linear IgA bullous dermatosis (LABD). Bullous pemphigoid is an autoimmune subepidermal blistering disease typically affecting patients older than 60 years.⁵ The pathogenesis of BP is related to development of autoantibodies directed against hemidesmosome components, bullous pemphigoid antigen (BPAG) 1 or BPAG2.⁵ Bullous pemphigoid presents clinically as widespread, generally pruritic, erythematous, urticarial plaques with bullae. Histologically, BP characteristically has a subepidermal split with superficial dermal edema and eosinophils at the dermoepidermal junction (Figure 1). Direct immunofluorescence confirms the diagnosis with IgG and C3 deposition in an n-serrated pattern at the dermoepidermal junction.⁶ Bullous pemphigoid can be distinguished from bullous LCV by the older age of presentation, DIF findings, and the absence of purpura.  

Linear IgA bullous dermatosis represents a rare subepidermal vesiculobullous disease occurring in patients in their 60s.⁷ Clinically, this entity presents as tense bullae often located on the periphery of an urticarial plaque, classically called the "string of pearls sign." Histologically, LABD also presents with subepidermal split; however, neutrophils are the predominant cell type vs eosinophils in BP (Figure 2).⁷ Direct immunofluorescence is specific with a linear deposition of IgA at the dermoepidermal junction. Linear IgA bullous dermatosis most commonly is induced by vancomycin. Unlike bullous LCV, the bullae of LABD have an annular peripheral pattern on an erythematous base and lack purpura.  

Stasis dermatitis is inflammation of the dermis due to venous insufficiency that often is present in the bilateral lower extremities. The disorder affects approximately 7% of adults older than 50 years, but it also can occur in younger patients.⁸ The pathophysiology of stasis dermatitis is caused by edema, which leads to extracellular fluid, plasma proteins, macrophages, and erythrocytes passing into the interstitial space. Patients with stasis dermatitis present with scaly erythematous papules and plaques or edematous blisters on the lower extremities. Diagnosis usually can be made clinically; however, a skin biopsy also can be helpful. Hematoxylin and eosin shows a pauci-inflammatory subepidermal bulla with fibrin (Figure 3).⁸ The overlying epidermis is intact. The dermis has cannon ball angiomatosis, red blood cell extravasation, and fibrosis typical of stasis dermatitis. Stasis dermatitis with bullae is cell poor and lacks the perivascular inflammatory infiltrate and neutrophilic fragments that often are present in LCV, making the 2 entities distinguishable. 

Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) lies on a spectrum of severe cutaneous drug reactions involving the skin and mucous membranes. Cutaneous involvement typically begins on the trunk and face and later can involve the palms and soles.⁹ Similar drugs have been implicated in bullous LCV and SJS/TEN, including nonsteroidal anti-inflammatory drugs and antibiotics. Histologically, SJS/TEN has full-thickness epidermal necrolysis, vacuolar interface, and keratinocyte apoptosis (Figure 4).⁹ The clinical presentation of sloughing of skin with positive Nikolsky sign, oral involvement, and H&E and DIF findings can help differentiate this entity from bullous LCV.  

The Diagnosis: Bullous Leukocytoclastic Vasculitis  

Histopathology with hematoxylin and eosin (H&E) stain showed a perivascular neutrophilic infiltrate, karyorrhexis, red blood cell extravasation, and fibrin deposition in the vessel wall (quiz images). Direct immunofluorescence (DIF) showed fibrin surrounding the vasculature, consistent with vasculitis. The clinical and histopathological evaluation supported the diagnosis of bullous leukocytoclastic vasculitis (LCV). The patient had a full LCV workup including antinuclear antibody, rheumatoid factor, hepatitis B and hepatitis C screening, erythrocyte sedimentation rate, C-reactive protein, and C3/C4/total complement level, which were all within reference range. The patient denied that she had taken any medications prior to the onset of the rash. She was started on a 12-day prednisone taper starting at 60 mg, and the rash resolved in 1 week.  

Although the incidence of LCV is estimated to be 30 cases per million individuals per year,¹ bullous LCV is a rarer entity with only a few cases reported in the literature.^2,3 As in our patient's case, up to 50% of LCV cases are idiopathic or the etiology cannot be determined despite laboratory workup and medication review. Other cases can be secondary to medication, infection, collagen vascular disease, or malignancy.³ Despite the exact pathogenesis of bullous LCV being unknown,⁴ it likely is related to a type III hypersensitivity reaction with immune complex deposition in postcapillary venules leading to endothelial injury, activation of the complement cascade, and development of intraepidermal or subepidermal blister formation depending on location of inflammation and edema.² Clinically, an intraepidermal split would be more flaccid, similar to pemphigus vulgaris, while a subepidermal split, as in our patient, would be taut bullae. The subepidermal split more commonly is seen in bullous LCV.²  

Leukocytoclastic vasculitis on H&E staining characteristically has a perivascular inflammatory infiltrate, neutrophilic fragments called leukocytoclasis, and blood extravasation.³ Extravasated blood presents clinically as petechiae. In this case, the petechiae helped distinguish this entity from the differential diagnosis. Furthermore, DIF would be helpful in distinguishing bullous diseases such as bullous pemphigoid (BP) and pemphigus vulgaris from LCV.² Direct immunofluorescence in bullous LCV would have fibrinogen surrounding the vasculature without C3 and IgG deposition (intraepidermal or subepidermal).  

Mild cases of LCV often resolve with supportive measures including elevation of the legs, ice packs applied to the affected area, and removal of the inciting drug or event.⁴ In the few cases reported in the literature, bullous LCV presented more diffusely than classic LCV with bullous lesions on the forearms and the lower extremities. Oral steroids are efficacious for extensive bullous LCV.⁴ 

The differential diagnosis of bullous LCV includes bullous diseases with subepidermal split including BP and linear IgA bullous dermatosis (LABD). Bullous pemphigoid is an autoimmune subepidermal blistering disease typically affecting patients older than 60 years.⁵ The pathogenesis of BP is related to development of autoantibodies directed against hemidesmosome components, bullous pemphigoid antigen (BPAG) 1 or BPAG2.⁵ Bullous pemphigoid presents clinically as widespread, generally pruritic, erythematous, urticarial plaques with bullae. Histologically, BP characteristically has a subepidermal split with superficial dermal edema and eosinophils at the dermoepidermal junction (Figure 1). Direct immunofluorescence confirms the diagnosis with IgG and C3 deposition in an n-serrated pattern at the dermoepidermal junction.⁶ Bullous pemphigoid can be distinguished from bullous LCV by the older age of presentation, DIF findings, and the absence of purpura.  

Linear IgA bullous dermatosis represents a rare subepidermal vesiculobullous disease occurring in patients in their 60s.⁷ Clinically, this entity presents as tense bullae often located on the periphery of an urticarial plaque, classically called the "string of pearls sign." Histologically, LABD also presents with subepidermal split; however, neutrophils are the predominant cell type vs eosinophils in BP (Figure 2).⁷ Direct immunofluorescence is specific with a linear deposition of IgA at the dermoepidermal junction. Linear IgA bullous dermatosis most commonly is induced by vancomycin. Unlike bullous LCV, the bullae of LABD have an annular peripheral pattern on an erythematous base and lack purpura.  

Stasis dermatitis is inflammation of the dermis due to venous insufficiency that often is present in the bilateral lower extremities. The disorder affects approximately 7% of adults older than 50 years, but it also can occur in younger patients.⁸ The pathophysiology of stasis dermatitis is caused by edema, which leads to extracellular fluid, plasma proteins, macrophages, and erythrocytes passing into the interstitial space. Patients with stasis dermatitis present with scaly erythematous papules and plaques or edematous blisters on the lower extremities. Diagnosis usually can be made clinically; however, a skin biopsy also can be helpful. Hematoxylin and eosin shows a pauci-inflammatory subepidermal bulla with fibrin (Figure 3).⁸ The overlying epidermis is intact. The dermis has cannon ball angiomatosis, red blood cell extravasation, and fibrosis typical of stasis dermatitis. Stasis dermatitis with bullae is cell poor and lacks the perivascular inflammatory infiltrate and neutrophilic fragments that often are present in LCV, making the 2 entities distinguishable. 

Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) lies on a spectrum of severe cutaneous drug reactions involving the skin and mucous membranes. Cutaneous involvement typically begins on the trunk and face and later can involve the palms and soles.⁹ Similar drugs have been implicated in bullous LCV and SJS/TEN, including nonsteroidal anti-inflammatory drugs and antibiotics. Histologically, SJS/TEN has full-thickness epidermal necrolysis, vacuolar interface, and keratinocyte apoptosis (Figure 4).⁹ The clinical presentation of sloughing of skin with positive Nikolsky sign, oral involvement, and H&E and DIF findings can help differentiate this entity from bullous LCV.  

To the Editor:

Syringomas are common benign tumors of the eccrine sweat glands that usually manifest clinically as multiple flesh-colored papules. They are most commonly seen on the face, neck, and chest of adolescent girls. Syringomas may appear at any site of the body but are rare in the vulva. We present a case of a 51-year-old woman who was referred to the Division of Gynecologic Oncology at the University of Alabama at Birmingham for further management of a tumor carrying a differential diagnosis of vulvar syringoma vs microcystic adnexal carcinoma (MAC).

A 51-year-old woman presented to dermatology (G.G.) and was referred to the Division of Gynecologic Oncology at the University of Alabama at Birmingham for further management of possible vulvar syringoma vs MAC. The patient previously had been evaluated at an outside community practice due to dyspareunia, vulvar discomfort, and vulvar irregularities of 1 month’s duration. At that time, a small biopsy was performed, and the histologic differential diagnosis included syringoma vs an adnexal carcinoma. Consequently, she was referred to gynecologic oncology for further management.

Pelvic examination revealed multilobular nodular areas overlying the clitoral hood that extended down to the labia majora. The nodular processes did not involve the clitoris, labia minora, or perineum. A mobile isolated lymph node measuring 2.0×1.0 cm in the right inguinal area also was noted. The patient’s clinical history was notable for right breast carcinoma treated with a right mastectomy with axillary lymph node dissection that showed metastatic disease. She also underwent adjuvant chemotherapy with paclitaxel and doxorubicin for breast carcinoma.

After discussing the diagnostic differential and treatment options, the patient elected to undergo a bilateral partial radical vulvectomy with reconstruction and resection of the right inguinal lymph node. Gross examination of the vulvectomy specimen showed multiple flesh-colored papules (Figure 1). Histologic examination revealed a neoplasm with sweat gland differentiation that was broad and poorly circumscribed but confined to the dermis (Figures 2A and 2B). The neoplasm was composed of epithelial cells that formed ductlike structures, lined by 2 layers of cuboidal epithelium within a fibrous stroma (Figure 2C). A toluidine blue special stain was performed and demonstrated an increased amount of mast cells in the tissue (Figure 3). Immunohistochemical stains for gross cystic disease fluid protein, estrogen receptor (ER), and progesterone receptor (PR) were negative in the tumor cells. The lack of cytologic atypia, perineural invasion, and deep infiltration into the subcutis favored a syringoma. One month later, the case was presented at the Tumor Board Conference at the University of Alabama at Birmingham where a final diagnosis of vulvar syringoma was agreed upon and discussed with the patient. At that time, no recurrence was evident and follow-up was recommended.

Syringomas may occur at any site on the body but are prone to occur on the periorbital area, especially the eyelids.¹ Some of the atypical locations for a syringoma include the anterior neck, chest, abdomen, genitals, axillae, groin, and buttocks.² Vulvar syringomas were first reported by Carneiro³ in 1971 as usually affecting adolescent girls and middle-aged women. There have been approximately 40 reported cases affecting women aged 8 to 78 years.^4,5 Vulvar syringomas classically appear as firm or soft, flesh-colored to transparent, papular lesions. The 2 other clinical variants are miliumlike, whitish, cystic papules as well as lichenoid papules.⁶ Pérez-Bustillo et al⁵ reported a case of the lichenoid papule variant on the labia majora of a 78-year-old woman who presented with intermittent vulvar pruritus of 4 years’ duration. Due to this patient’s 9-year history of urinary incontinence, the lesions had been misdiagnosed as irritant dermatitis and associated lichen simplex chronicus (LSC). This case is a reminder to consider vulvar syringoma in patients with LSC who respond poorly to oral antihistamines and topical steroids.⁵ Rarely, multiple clinical variants may coexist. In a case reported by Dereli et al,⁷ a 19-year-old woman presented with concurrent classical and miliumlike forms of vulvar syringoma.

Vulvar syringomas usually present as multiple lesions involving both sides of the labia majora; however, Blasdale and McLelland⁸ reported a single isolated syringoma of the vulva on the anterior right labia minora that measured 1.0×0.5 cm, leading the lesion to be described as a giant syringoma.

Vulvar syringomas usually are asymptomatic and noticed during routine gynecologic examination. Therefore, it is believed that they likely are underdiagnosed.⁵ When symptomatic, they commonly present with constant⁹ or intermittent⁵ pruritus, which may intensify during menstruation, pregnancy, and summertime.^6,10-12 Gerdsen et al¹⁰ documented a 27-year-old woman who presented with a 2-year history of pruritic vulvar skin lesions that became exacerbated during menstruation, which raised the possibility of cyclical hormonal changes being responsible for periodic exacerbation of vulvar pruritus during menstruation. In addition, patients may experience an increase in size and number of the lesions during pregnancy. Bal et al¹¹ reported a 24-year-old primigravida with vulvar papular lesions that intensified during pregnancy. She had experienced intermittent vulvar pruritus for 12 years but had no change in symptoms during menstruation.¹¹ Few studies have attempted to evaluate the presence of ER and PR in the syringomas. A study of 9 nonvulvar syringomas by Wallace and Smoller¹³ showed ER positivity in 1 case and PR positivity in 8 cases, lending support to the hormonal theory; however, in another case series of 15 vulvar syringomas, Huang et al⁶ failed to show ER and PR expression by immunohistochemical staining. A case report published 3 years earlier documented the first case of PR positivity on a vulvar syringoma.¹⁴ Our patient also was negative for ER and PR, which suggested that hormonal status is important in some but not all syringomas.

Patients with vulgar syringomas also might have coexisting extragenital syringomas in the neck,⁴ eyelids,^6,7,10 and periorbital area,⁶ and thorough examination of the body is essential. If an extragenital syringoma is diagnosed, a vulvar syringoma should be considered, especially when the patient presents with unexplained genital symptoms. Although no proven hereditary transmission pattern has been established, family history of syringomas has been established in several cases.¹⁵ In a case series reported by Huang et al,⁶ 4 of 18 patients reported a family history of periorbital syringomas. In our case, the patient did not report a family history of syringomas.

The differential diagnosis of vulvar lesions with pruritus is broad and includes Fox-Fordyce disease, lichen planus, LSC, epidermal cysts, senile angiomas, dystrophic calcinosis, xanthomas, steatocytomas, soft fibromas, condyloma acuminatum, and candidiasis. Vulvar syringomas might have a nonspecific appearance, and histologic examination is essential to confirm the diagnosis and rule out any malignant process such as MAC, vulvar intraepithelial neoplasia, extramammary Paget disease, or other glandular neoplasms of the vulva.

Microcystic adnexal carcinoma was first reported in 1982 by Goldstein et al¹⁶ as a locally aggressive neoplasm that can be confused with benign adnexal neoplasms, particularly desmoplastic trichoepithelioma, trichoadenoma, and syringoma. Microcystic adnexal carcinomas present as slow-growing, flesh-colored papules that may resemble syringomas and appear in similar body sites. Histologic examination is essential to differentiate between these two entities. Syringomas are tumors confined to the dermis and are composed of multiple small ducts lined by 2 layers of cuboidal epithelium within a dense fibrous stroma. Unlike syringomas, MACs usually infiltrate diffusely into the dermis and subcutis and may extend into the underlying muscle. Although bland cytologic features predominate, perineural invasion frequently is present in MACs. A potential pitfall of misdiagnosis can be caused by a superficial biopsy that may reveal benign histologic appearance, particularly in the upper level of the tumor where it may be confused with a syringoma or a benign follicular neoplasm.¹⁷

The initial biopsy performed on our patient was possibly not deep enough to render an unequivocal diagnosis and therefore bilateral partial radical vulvectomy was considered. After surgery, histologic examination of the resection specimen revealed a poorly circumscribed tumor confined to the dermis. The tumor was broad and the lack of deep infiltration into the subcutis and perineural invasion favored a syringoma (Figures 2A and 2B). These findings were consistent with case reports that documented syringomas as being more wide than deep on microscopic examination, whereas the opposite pertained to MAC.¹⁸ Cases of plaque-type syringomas that initially were misdiagnosed as MACs also have been reported.¹⁹ Because misdiagnosis may affect the treatment plan and potentially result in unnecessary surgery, caution should be taken when differentiating between these two entities. When a definitive diagnosis cannot be rendered on a superficial biopsy, a recommendation should be made for a deeper biopsy sampling the subcutis.

For the majority of the patients with vulvar syringomas, treatment is seldom required due to their asymptomatic nature; however, patients who present with symptoms usually report pruritus of variable intensities and patterns. A standardized treatment does not exist for vulvar syringomas, and oral or topical treatment might be used as an initial approach. Commonly prescribed medications with variable results include topical corticosteroids, oral antihistamines, and topical retinoids. In a case reported by Iwao et al,²⁰ vulvar syringomas were successfully treated with tranilast, which has anti-inflammatory and immunomodulatory effects. This medication could have a possible dual action—inhibiting the release of chemical mediators from the mast cells and inhibiting the release of IL-1β from the eccrine duct, which could suppress the proliferation of stromal connective tissue. Our case was stained with toluidine blue and showed an increased number of mast cells in the tissue (Figure 3). Patients who are unresponsive to tranilast or have extensive disease resulting in cosmetic disfigurement might benefit from more invasive treatment methods including a variety of lasers, cryotherapy, electrosurgery, and excision. Excisions should include the entire tumor to avoid recurrence. In a case reported by Garman and Metry,²¹ the lesions were surgically excised using small 2- to 3-mm punches; however, several weeks later the lesions recurred. Our patient presented with a 1-month evolution of dyspareunia, vulvar discomfort, and vulvar irregularities that were probably not treated with oral or topical medications before being referred for surgery.

We report a case of a vulvar syringoma that presented diagnostic challenges in the initial biopsy, which prevented the exclusion of an MAC. After partial radical vulvectomy, histologic examination was more definitive, showing lack of deep infiltration into the subcutis or perineural invasion that are commonly seen in MAC. This case is an example of a notable pitfall in the diagnosis of vulvar syringoma on a limited biopsy leading to overtreatment. Raising awareness of this entity is the only modality to prevent misdiagnosis. We encourage reporting of further cases of syringomas, particularly those with atypical locations or patterns that may cause diagnostic problems.

To the Editor:

Syringomas are common benign tumors of the eccrine sweat glands that usually manifest clinically as multiple flesh-colored papules. They are most commonly seen on the face, neck, and chest of adolescent girls. Syringomas may appear at any site of the body but are rare in the vulva. We present a case of a 51-year-old woman who was referred to the Division of Gynecologic Oncology at the University of Alabama at Birmingham for further management of a tumor carrying a differential diagnosis of vulvar syringoma vs microcystic adnexal carcinoma (MAC).

A 51-year-old woman presented to dermatology (G.G.) and was referred to the Division of Gynecologic Oncology at the University of Alabama at Birmingham for further management of possible vulvar syringoma vs MAC. The patient previously had been evaluated at an outside community practice due to dyspareunia, vulvar discomfort, and vulvar irregularities of 1 month’s duration. At that time, a small biopsy was performed, and the histologic differential diagnosis included syringoma vs an adnexal carcinoma. Consequently, she was referred to gynecologic oncology for further management.

Pelvic examination revealed multilobular nodular areas overlying the clitoral hood that extended down to the labia majora. The nodular processes did not involve the clitoris, labia minora, or perineum. A mobile isolated lymph node measuring 2.0×1.0 cm in the right inguinal area also was noted. The patient’s clinical history was notable for right breast carcinoma treated with a right mastectomy with axillary lymph node dissection that showed metastatic disease. She also underwent adjuvant chemotherapy with paclitaxel and doxorubicin for breast carcinoma.

After discussing the diagnostic differential and treatment options, the patient elected to undergo a bilateral partial radical vulvectomy with reconstruction and resection of the right inguinal lymph node. Gross examination of the vulvectomy specimen showed multiple flesh-colored papules (Figure 1). Histologic examination revealed a neoplasm with sweat gland differentiation that was broad and poorly circumscribed but confined to the dermis (Figures 2A and 2B). The neoplasm was composed of epithelial cells that formed ductlike structures, lined by 2 layers of cuboidal epithelium within a fibrous stroma (Figure 2C). A toluidine blue special stain was performed and demonstrated an increased amount of mast cells in the tissue (Figure 3). Immunohistochemical stains for gross cystic disease fluid protein, estrogen receptor (ER), and progesterone receptor (PR) were negative in the tumor cells. The lack of cytologic atypia, perineural invasion, and deep infiltration into the subcutis favored a syringoma. One month later, the case was presented at the Tumor Board Conference at the University of Alabama at Birmingham where a final diagnosis of vulvar syringoma was agreed upon and discussed with the patient. At that time, no recurrence was evident and follow-up was recommended.

Syringomas may occur at any site on the body but are prone to occur on the periorbital area, especially the eyelids.¹ Some of the atypical locations for a syringoma include the anterior neck, chest, abdomen, genitals, axillae, groin, and buttocks.² Vulvar syringomas were first reported by Carneiro³ in 1971 as usually affecting adolescent girls and middle-aged women. There have been approximately 40 reported cases affecting women aged 8 to 78 years.^4,5 Vulvar syringomas classically appear as firm or soft, flesh-colored to transparent, papular lesions. The 2 other clinical variants are miliumlike, whitish, cystic papules as well as lichenoid papules.⁶ Pérez-Bustillo et al⁵ reported a case of the lichenoid papule variant on the labia majora of a 78-year-old woman who presented with intermittent vulvar pruritus of 4 years’ duration. Due to this patient’s 9-year history of urinary incontinence, the lesions had been misdiagnosed as irritant dermatitis and associated lichen simplex chronicus (LSC). This case is a reminder to consider vulvar syringoma in patients with LSC who respond poorly to oral antihistamines and topical steroids.⁵ Rarely, multiple clinical variants may coexist. In a case reported by Dereli et al,⁷ a 19-year-old woman presented with concurrent classical and miliumlike forms of vulvar syringoma.

Vulvar syringomas usually present as multiple lesions involving both sides of the labia majora; however, Blasdale and McLelland⁸ reported a single isolated syringoma of the vulva on the anterior right labia minora that measured 1.0×0.5 cm, leading the lesion to be described as a giant syringoma.

Vulvar syringomas usually are asymptomatic and noticed during routine gynecologic examination. Therefore, it is believed that they likely are underdiagnosed.⁵ When symptomatic, they commonly present with constant⁹ or intermittent⁵ pruritus, which may intensify during menstruation, pregnancy, and summertime.^6,10-12 Gerdsen et al¹⁰ documented a 27-year-old woman who presented with a 2-year history of pruritic vulvar skin lesions that became exacerbated during menstruation, which raised the possibility of cyclical hormonal changes being responsible for periodic exacerbation of vulvar pruritus during menstruation. In addition, patients may experience an increase in size and number of the lesions during pregnancy. Bal et al¹¹ reported a 24-year-old primigravida with vulvar papular lesions that intensified during pregnancy. She had experienced intermittent vulvar pruritus for 12 years but had no change in symptoms during menstruation.¹¹ Few studies have attempted to evaluate the presence of ER and PR in the syringomas. A study of 9 nonvulvar syringomas by Wallace and Smoller¹³ showed ER positivity in 1 case and PR positivity in 8 cases, lending support to the hormonal theory; however, in another case series of 15 vulvar syringomas, Huang et al⁶ failed to show ER and PR expression by immunohistochemical staining. A case report published 3 years earlier documented the first case of PR positivity on a vulvar syringoma.¹⁴ Our patient also was negative for ER and PR, which suggested that hormonal status is important in some but not all syringomas.

Patients with vulgar syringomas also might have coexisting extragenital syringomas in the neck,⁴ eyelids,^6,7,10 and periorbital area,⁶ and thorough examination of the body is essential. If an extragenital syringoma is diagnosed, a vulvar syringoma should be considered, especially when the patient presents with unexplained genital symptoms. Although no proven hereditary transmission pattern has been established, family history of syringomas has been established in several cases.¹⁵ In a case series reported by Huang et al,⁶ 4 of 18 patients reported a family history of periorbital syringomas. In our case, the patient did not report a family history of syringomas.

The differential diagnosis of vulvar lesions with pruritus is broad and includes Fox-Fordyce disease, lichen planus, LSC, epidermal cysts, senile angiomas, dystrophic calcinosis, xanthomas, steatocytomas, soft fibromas, condyloma acuminatum, and candidiasis. Vulvar syringomas might have a nonspecific appearance, and histologic examination is essential to confirm the diagnosis and rule out any malignant process such as MAC, vulvar intraepithelial neoplasia, extramammary Paget disease, or other glandular neoplasms of the vulva.

Microcystic adnexal carcinoma was first reported in 1982 by Goldstein et al¹⁶ as a locally aggressive neoplasm that can be confused with benign adnexal neoplasms, particularly desmoplastic trichoepithelioma, trichoadenoma, and syringoma. Microcystic adnexal carcinomas present as slow-growing, flesh-colored papules that may resemble syringomas and appear in similar body sites. Histologic examination is essential to differentiate between these two entities. Syringomas are tumors confined to the dermis and are composed of multiple small ducts lined by 2 layers of cuboidal epithelium within a dense fibrous stroma. Unlike syringomas, MACs usually infiltrate diffusely into the dermis and subcutis and may extend into the underlying muscle. Although bland cytologic features predominate, perineural invasion frequently is present in MACs. A potential pitfall of misdiagnosis can be caused by a superficial biopsy that may reveal benign histologic appearance, particularly in the upper level of the tumor where it may be confused with a syringoma or a benign follicular neoplasm.¹⁷

The initial biopsy performed on our patient was possibly not deep enough to render an unequivocal diagnosis and therefore bilateral partial radical vulvectomy was considered. After surgery, histologic examination of the resection specimen revealed a poorly circumscribed tumor confined to the dermis. The tumor was broad and the lack of deep infiltration into the subcutis and perineural invasion favored a syringoma (Figures 2A and 2B). These findings were consistent with case reports that documented syringomas as being more wide than deep on microscopic examination, whereas the opposite pertained to MAC.¹⁸ Cases of plaque-type syringomas that initially were misdiagnosed as MACs also have been reported.¹⁹ Because misdiagnosis may affect the treatment plan and potentially result in unnecessary surgery, caution should be taken when differentiating between these two entities. When a definitive diagnosis cannot be rendered on a superficial biopsy, a recommendation should be made for a deeper biopsy sampling the subcutis.

For the majority of the patients with vulvar syringomas, treatment is seldom required due to their asymptomatic nature; however, patients who present with symptoms usually report pruritus of variable intensities and patterns. A standardized treatment does not exist for vulvar syringomas, and oral or topical treatment might be used as an initial approach. Commonly prescribed medications with variable results include topical corticosteroids, oral antihistamines, and topical retinoids. In a case reported by Iwao et al,²⁰ vulvar syringomas were successfully treated with tranilast, which has anti-inflammatory and immunomodulatory effects. This medication could have a possible dual action—inhibiting the release of chemical mediators from the mast cells and inhibiting the release of IL-1β from the eccrine duct, which could suppress the proliferation of stromal connective tissue. Our case was stained with toluidine blue and showed an increased number of mast cells in the tissue (Figure 3). Patients who are unresponsive to tranilast or have extensive disease resulting in cosmetic disfigurement might benefit from more invasive treatment methods including a variety of lasers, cryotherapy, electrosurgery, and excision. Excisions should include the entire tumor to avoid recurrence. In a case reported by Garman and Metry,²¹ the lesions were surgically excised using small 2- to 3-mm punches; however, several weeks later the lesions recurred. Our patient presented with a 1-month evolution of dyspareunia, vulvar discomfort, and vulvar irregularities that were probably not treated with oral or topical medications before being referred for surgery.

We report a case of a vulvar syringoma that presented diagnostic challenges in the initial biopsy, which prevented the exclusion of an MAC. After partial radical vulvectomy, histologic examination was more definitive, showing lack of deep infiltration into the subcutis or perineural invasion that are commonly seen in MAC. This case is an example of a notable pitfall in the diagnosis of vulvar syringoma on a limited biopsy leading to overtreatment. Raising awareness of this entity is the only modality to prevent misdiagnosis. We encourage reporting of further cases of syringomas, particularly those with atypical locations or patterns that may cause diagnostic problems.

To the Editor:

Syringomas are common benign tumors of the eccrine sweat glands that usually manifest clinically as multiple flesh-colored papules. They are most commonly seen on the face, neck, and chest of adolescent girls. Syringomas may appear at any site of the body but are rare in the vulva. We present a case of a 51-year-old woman who was referred to the Division of Gynecologic Oncology at the University of Alabama at Birmingham for further management of a tumor carrying a differential diagnosis of vulvar syringoma vs microcystic adnexal carcinoma (MAC).

A 51-year-old woman presented to dermatology (G.G.) and was referred to the Division of Gynecologic Oncology at the University of Alabama at Birmingham for further management of possible vulvar syringoma vs MAC. The patient previously had been evaluated at an outside community practice due to dyspareunia, vulvar discomfort, and vulvar irregularities of 1 month’s duration. At that time, a small biopsy was performed, and the histologic differential diagnosis included syringoma vs an adnexal carcinoma. Consequently, she was referred to gynecologic oncology for further management.

Pelvic examination revealed multilobular nodular areas overlying the clitoral hood that extended down to the labia majora. The nodular processes did not involve the clitoris, labia minora, or perineum. A mobile isolated lymph node measuring 2.0×1.0 cm in the right inguinal area also was noted. The patient’s clinical history was notable for right breast carcinoma treated with a right mastectomy with axillary lymph node dissection that showed metastatic disease. She also underwent adjuvant chemotherapy with paclitaxel and doxorubicin for breast carcinoma.

After discussing the diagnostic differential and treatment options, the patient elected to undergo a bilateral partial radical vulvectomy with reconstruction and resection of the right inguinal lymph node. Gross examination of the vulvectomy specimen showed multiple flesh-colored papules (Figure 1). Histologic examination revealed a neoplasm with sweat gland differentiation that was broad and poorly circumscribed but confined to the dermis (Figures 2A and 2B). The neoplasm was composed of epithelial cells that formed ductlike structures, lined by 2 layers of cuboidal epithelium within a fibrous stroma (Figure 2C). A toluidine blue special stain was performed and demonstrated an increased amount of mast cells in the tissue (Figure 3). Immunohistochemical stains for gross cystic disease fluid protein, estrogen receptor (ER), and progesterone receptor (PR) were negative in the tumor cells. The lack of cytologic atypia, perineural invasion, and deep infiltration into the subcutis favored a syringoma. One month later, the case was presented at the Tumor Board Conference at the University of Alabama at Birmingham where a final diagnosis of vulvar syringoma was agreed upon and discussed with the patient. At that time, no recurrence was evident and follow-up was recommended.

Syringomas may occur at any site on the body but are prone to occur on the periorbital area, especially the eyelids.¹ Some of the atypical locations for a syringoma include the anterior neck, chest, abdomen, genitals, axillae, groin, and buttocks.² Vulvar syringomas were first reported by Carneiro³ in 1971 as usually affecting adolescent girls and middle-aged women. There have been approximately 40 reported cases affecting women aged 8 to 78 years.^4,5 Vulvar syringomas classically appear as firm or soft, flesh-colored to transparent, papular lesions. The 2 other clinical variants are miliumlike, whitish, cystic papules as well as lichenoid papules.⁶ Pérez-Bustillo et al⁵ reported a case of the lichenoid papule variant on the labia majora of a 78-year-old woman who presented with intermittent vulvar pruritus of 4 years’ duration. Due to this patient’s 9-year history of urinary incontinence, the lesions had been misdiagnosed as irritant dermatitis and associated lichen simplex chronicus (LSC). This case is a reminder to consider vulvar syringoma in patients with LSC who respond poorly to oral antihistamines and topical steroids.⁵ Rarely, multiple clinical variants may coexist. In a case reported by Dereli et al,⁷ a 19-year-old woman presented with concurrent classical and miliumlike forms of vulvar syringoma.

Vulvar syringomas usually present as multiple lesions involving both sides of the labia majora; however, Blasdale and McLelland⁸ reported a single isolated syringoma of the vulva on the anterior right labia minora that measured 1.0×0.5 cm, leading the lesion to be described as a giant syringoma.

Vulvar syringomas usually are asymptomatic and noticed during routine gynecologic examination. Therefore, it is believed that they likely are underdiagnosed.⁵ When symptomatic, they commonly present with constant⁹ or intermittent⁵ pruritus, which may intensify during menstruation, pregnancy, and summertime.^6,10-12 Gerdsen et al¹⁰ documented a 27-year-old woman who presented with a 2-year history of pruritic vulvar skin lesions that became exacerbated during menstruation, which raised the possibility of cyclical hormonal changes being responsible for periodic exacerbation of vulvar pruritus during menstruation. In addition, patients may experience an increase in size and number of the lesions during pregnancy. Bal et al¹¹ reported a 24-year-old primigravida with vulvar papular lesions that intensified during pregnancy. She had experienced intermittent vulvar pruritus for 12 years but had no change in symptoms during menstruation.¹¹ Few studies have attempted to evaluate the presence of ER and PR in the syringomas. A study of 9 nonvulvar syringomas by Wallace and Smoller¹³ showed ER positivity in 1 case and PR positivity in 8 cases, lending support to the hormonal theory; however, in another case series of 15 vulvar syringomas, Huang et al⁶ failed to show ER and PR expression by immunohistochemical staining. A case report published 3 years earlier documented the first case of PR positivity on a vulvar syringoma.¹⁴ Our patient also was negative for ER and PR, which suggested that hormonal status is important in some but not all syringomas.

Patients with vulgar syringomas also might have coexisting extragenital syringomas in the neck,⁴ eyelids,^6,7,10 and periorbital area,⁶ and thorough examination of the body is essential. If an extragenital syringoma is diagnosed, a vulvar syringoma should be considered, especially when the patient presents with unexplained genital symptoms. Although no proven hereditary transmission pattern has been established, family history of syringomas has been established in several cases.¹⁵ In a case series reported by Huang et al,⁶ 4 of 18 patients reported a family history of periorbital syringomas. In our case, the patient did not report a family history of syringomas.

The differential diagnosis of vulvar lesions with pruritus is broad and includes Fox-Fordyce disease, lichen planus, LSC, epidermal cysts, senile angiomas, dystrophic calcinosis, xanthomas, steatocytomas, soft fibromas, condyloma acuminatum, and candidiasis. Vulvar syringomas might have a nonspecific appearance, and histologic examination is essential to confirm the diagnosis and rule out any malignant process such as MAC, vulvar intraepithelial neoplasia, extramammary Paget disease, or other glandular neoplasms of the vulva.

Microcystic adnexal carcinoma was first reported in 1982 by Goldstein et al¹⁶ as a locally aggressive neoplasm that can be confused with benign adnexal neoplasms, particularly desmoplastic trichoepithelioma, trichoadenoma, and syringoma. Microcystic adnexal carcinomas present as slow-growing, flesh-colored papules that may resemble syringomas and appear in similar body sites. Histologic examination is essential to differentiate between these two entities. Syringomas are tumors confined to the dermis and are composed of multiple small ducts lined by 2 layers of cuboidal epithelium within a dense fibrous stroma. Unlike syringomas, MACs usually infiltrate diffusely into the dermis and subcutis and may extend into the underlying muscle. Although bland cytologic features predominate, perineural invasion frequently is present in MACs. A potential pitfall of misdiagnosis can be caused by a superficial biopsy that may reveal benign histologic appearance, particularly in the upper level of the tumor where it may be confused with a syringoma or a benign follicular neoplasm.¹⁷

The initial biopsy performed on our patient was possibly not deep enough to render an unequivocal diagnosis and therefore bilateral partial radical vulvectomy was considered. After surgery, histologic examination of the resection specimen revealed a poorly circumscribed tumor confined to the dermis. The tumor was broad and the lack of deep infiltration into the subcutis and perineural invasion favored a syringoma (Figures 2A and 2B). These findings were consistent with case reports that documented syringomas as being more wide than deep on microscopic examination, whereas the opposite pertained to MAC.¹⁸ Cases of plaque-type syringomas that initially were misdiagnosed as MACs also have been reported.¹⁹ Because misdiagnosis may affect the treatment plan and potentially result in unnecessary surgery, caution should be taken when differentiating between these two entities. When a definitive diagnosis cannot be rendered on a superficial biopsy, a recommendation should be made for a deeper biopsy sampling the subcutis.

For the majority of the patients with vulvar syringomas, treatment is seldom required due to their asymptomatic nature; however, patients who present with symptoms usually report pruritus of variable intensities and patterns. A standardized treatment does not exist for vulvar syringomas, and oral or topical treatment might be used as an initial approach. Commonly prescribed medications with variable results include topical corticosteroids, oral antihistamines, and topical retinoids. In a case reported by Iwao et al,²⁰ vulvar syringomas were successfully treated with tranilast, which has anti-inflammatory and immunomodulatory effects. This medication could have a possible dual action—inhibiting the release of chemical mediators from the mast cells and inhibiting the release of IL-1β from the eccrine duct, which could suppress the proliferation of stromal connective tissue. Our case was stained with toluidine blue and showed an increased number of mast cells in the tissue (Figure 3). Patients who are unresponsive to tranilast or have extensive disease resulting in cosmetic disfigurement might benefit from more invasive treatment methods including a variety of lasers, cryotherapy, electrosurgery, and excision. Excisions should include the entire tumor to avoid recurrence. In a case reported by Garman and Metry,²¹ the lesions were surgically excised using small 2- to 3-mm punches; however, several weeks later the lesions recurred. Our patient presented with a 1-month evolution of dyspareunia, vulvar discomfort, and vulvar irregularities that were probably not treated with oral or topical medications before being referred for surgery.

We report a case of a vulvar syringoma that presented diagnostic challenges in the initial biopsy, which prevented the exclusion of an MAC. After partial radical vulvectomy, histologic examination was more definitive, showing lack of deep infiltration into the subcutis or perineural invasion that are commonly seen in MAC. This case is an example of a notable pitfall in the diagnosis of vulvar syringoma on a limited biopsy leading to overtreatment. Raising awareness of this entity is the only modality to prevent misdiagnosis. We encourage reporting of further cases of syringomas, particularly those with atypical locations or patterns that may cause diagnostic problems.

To the Editor:

Sweet syndrome (SS), also known as acute febrile neutrophilic dermatosis, is an uncommon inflammatory skin disorder characterized by sudden onset of fever, leukocytosis, neutrophilia, and tender erythematous papules or plaques or both. Skin biopsy usually reveals extensive infiltration of neutrophils into the epidermis and dermis.^1-3 Although rare, cases of eosinophil-rich SS have been reported in patients with drug-induced and malignancy-associated SS.^4,5 We report a case of a patient with classical SS with dermal eosinophilic infiltration.

An 80-year-old Hispanic man presented with abrupt onset of a rash on the posterior scalp, left ear, back, and hands of 5 days’ duration. The lesions were painful and had progressed to the point of impairing hand grip. The patient’s medical history included a reported common cold the week prior, hyperlipidemia, and hypertension, for which he took metoprolol, simvastatin, aspirin, and clopidogrel. He denied oral lesions and medication changes. He was afebrile and did not experience dietary changes, weight loss, or fatigue. He recently returned from travel to the Dominican Republic.

Physical examination revealed tender, well demarcated, pink to violaceous, pseudovesicular papules and plaques on the palms and dorsal hands (Figure 1), the posterior scalp, left ear, proximal left arm, and back. Pink, juicy, targetoid papules were also found on the scalp, back, and left arm. There was no evidence of lymphadenopathy. Laboratory test results revealed an elevated white blood cell count (11,500/µL [reference range, 3800-10,800/µL]), absolute neutrophil count (8073/µL [reference range, 1500–7800/µL]), and eosinophil count (610/µL [reference range, 15–500/µL]). These results indicated leukocytosis with neutrophilia and mild eosinophilia. The patient also was anemic (hemoglobin, 11.5 g/dL [reference range, 13.2–17.1 g/dL]; hematocrit, 35.1% [reference range, 38.5%–50%]). Urine testing revealed altered renal function (serum creatinine, 2.42 mg/dL [reference range, 0.7–1.1 mg/dL]; blood urea nitrogen, 34 mg/dL [reference range, 7–25 mg/dL]; glomerular filtration rate, 4 mL/min/1.73 m² (reference range, ≥60 mL/min/1.73 m²]), suggesting stage 4 chronic kidney disease. Urinalysis showed mild hematuria and proteinuria.

In our patient, the observed clinical and histological findings were consistent with a diagnosis of SS,^2,10 specifically tender erythematous plaques of sudden onset, fast response to systemic corticosteroid therapy, a dermal neutrophilic infiltrate without evidence of leukocytoclastic vasculitis, and leukocytosis greater than 8000/µL with more than 70% neutrophils. He also exhibited targetoid lesions, which have been reported in 7% to 12% of SS patients.^10,11

The predominant cells involved in the dermis of SS lesions are mature neutrophils; however, eosinophils have been observed in small numbers within dermal infiltrates in skin lesions of patients with either classical SS or drug-induced dermatosis.² In 2 studies of cases of SS (N=73 and N=31), eosinophils were reported in 35% and 41% of skin biopsies, respectively.^4,5 Nevertheless, cases with dense eosinophilic infiltrates are rare. Furthermore, Masuda et al¹² reported a case of eosinophil-rich SS in a 29-year-old woman after treatment of an upper respiratory tract infection with an antibiotic, and Soon et al¹³ described an eosinophil-rich case of SS in the setting of new-onset enteropathy-associated T-cell lymphoma.

Our patient was considered to have classical SS because he had an episode of an upper respiratory tract infection 1 week prior to onset of clinical manifestations. The histologic finding of numerous eosinophils in our case was unusual for idiopathic SS. This finding might suggest a drug hypersensitivity reaction, but the lack of any change in the patient’s long-term medication list and the lack of any other episodes made a diagnosis of drug-induced SS less likely in our patient.

Eosinophilic dermatosis of hematologic malignancy is a rare cutaneous condition in which nodules, pruritic papules, and vesicles arise in patients with a hematologic malignancy, such as chronic lymphocytic leukemia and mantle cell lymphoma,¹³ in which a deep perivascular lymphocytic infiltrate and numerous eosinophils are observed. Malignancy was ruled out in our patient because of the lack of characteristic abnormalities in blood testing, the fast response to corticosteroid therapy, and the lack of recurrence posttreatment or additional systemic concerns.

The typical pathology findings of SS consist of mature neutrophils found in the dermis without evidence of leukocytoclastic vasculitis. Eosinophil-rich infiltration, however rare, has been reported in SS. This report highlights a case of classical SS with a particularly dense eosinophilic infiltrate, which could be mistaken for other eosinophilic dermatoses. Dermatologists should be aware of the possibility of marked eosinophilic infiltration in all subtypes of this disorder.

To the Editor:

Sweet syndrome (SS), also known as acute febrile neutrophilic dermatosis, is an uncommon inflammatory skin disorder characterized by sudden onset of fever, leukocytosis, neutrophilia, and tender erythematous papules or plaques or both. Skin biopsy usually reveals extensive infiltration of neutrophils into the epidermis and dermis.^1-3 Although rare, cases of eosinophil-rich SS have been reported in patients with drug-induced and malignancy-associated SS.^4,5 We report a case of a patient with classical SS with dermal eosinophilic infiltration.

An 80-year-old Hispanic man presented with abrupt onset of a rash on the posterior scalp, left ear, back, and hands of 5 days’ duration. The lesions were painful and had progressed to the point of impairing hand grip. The patient’s medical history included a reported common cold the week prior, hyperlipidemia, and hypertension, for which he took metoprolol, simvastatin, aspirin, and clopidogrel. He denied oral lesions and medication changes. He was afebrile and did not experience dietary changes, weight loss, or fatigue. He recently returned from travel to the Dominican Republic.

Physical examination revealed tender, well demarcated, pink to violaceous, pseudovesicular papules and plaques on the palms and dorsal hands (Figure 1), the posterior scalp, left ear, proximal left arm, and back. Pink, juicy, targetoid papules were also found on the scalp, back, and left arm. There was no evidence of lymphadenopathy. Laboratory test results revealed an elevated white blood cell count (11,500/µL [reference range, 3800-10,800/µL]), absolute neutrophil count (8073/µL [reference range, 1500–7800/µL]), and eosinophil count (610/µL [reference range, 15–500/µL]). These results indicated leukocytosis with neutrophilia and mild eosinophilia. The patient also was anemic (hemoglobin, 11.5 g/dL [reference range, 13.2–17.1 g/dL]; hematocrit, 35.1% [reference range, 38.5%–50%]). Urine testing revealed altered renal function (serum creatinine, 2.42 mg/dL [reference range, 0.7–1.1 mg/dL]; blood urea nitrogen, 34 mg/dL [reference range, 7–25 mg/dL]; glomerular filtration rate, 4 mL/min/1.73 m² (reference range, ≥60 mL/min/1.73 m²]), suggesting stage 4 chronic kidney disease. Urinalysis showed mild hematuria and proteinuria.

In our patient, the observed clinical and histological findings were consistent with a diagnosis of SS,^2,10 specifically tender erythematous plaques of sudden onset, fast response to systemic corticosteroid therapy, a dermal neutrophilic infiltrate without evidence of leukocytoclastic vasculitis, and leukocytosis greater than 8000/µL with more than 70% neutrophils. He also exhibited targetoid lesions, which have been reported in 7% to 12% of SS patients.^10,11

The predominant cells involved in the dermis of SS lesions are mature neutrophils; however, eosinophils have been observed in small numbers within dermal infiltrates in skin lesions of patients with either classical SS or drug-induced dermatosis.² In 2 studies of cases of SS (N=73 and N=31), eosinophils were reported in 35% and 41% of skin biopsies, respectively.^4,5 Nevertheless, cases with dense eosinophilic infiltrates are rare. Furthermore, Masuda et al¹² reported a case of eosinophil-rich SS in a 29-year-old woman after treatment of an upper respiratory tract infection with an antibiotic, and Soon et al¹³ described an eosinophil-rich case of SS in the setting of new-onset enteropathy-associated T-cell lymphoma.

Our patient was considered to have classical SS because he had an episode of an upper respiratory tract infection 1 week prior to onset of clinical manifestations. The histologic finding of numerous eosinophils in our case was unusual for idiopathic SS. This finding might suggest a drug hypersensitivity reaction, but the lack of any change in the patient’s long-term medication list and the lack of any other episodes made a diagnosis of drug-induced SS less likely in our patient.

Eosinophilic dermatosis of hematologic malignancy is a rare cutaneous condition in which nodules, pruritic papules, and vesicles arise in patients with a hematologic malignancy, such as chronic lymphocytic leukemia and mantle cell lymphoma,¹³ in which a deep perivascular lymphocytic infiltrate and numerous eosinophils are observed. Malignancy was ruled out in our patient because of the lack of characteristic abnormalities in blood testing, the fast response to corticosteroid therapy, and the lack of recurrence posttreatment or additional systemic concerns.

The typical pathology findings of SS consist of mature neutrophils found in the dermis without evidence of leukocytoclastic vasculitis. Eosinophil-rich infiltration, however rare, has been reported in SS. This report highlights a case of classical SS with a particularly dense eosinophilic infiltrate, which could be mistaken for other eosinophilic dermatoses. Dermatologists should be aware of the possibility of marked eosinophilic infiltration in all subtypes of this disorder.

To the Editor:

Sweet syndrome (SS), also known as acute febrile neutrophilic dermatosis, is an uncommon inflammatory skin disorder characterized by sudden onset of fever, leukocytosis, neutrophilia, and tender erythematous papules or plaques or both. Skin biopsy usually reveals extensive infiltration of neutrophils into the epidermis and dermis.^1-3 Although rare, cases of eosinophil-rich SS have been reported in patients with drug-induced and malignancy-associated SS.^4,5 We report a case of a patient with classical SS with dermal eosinophilic infiltration.

An 80-year-old Hispanic man presented with abrupt onset of a rash on the posterior scalp, left ear, back, and hands of 5 days’ duration. The lesions were painful and had progressed to the point of impairing hand grip. The patient’s medical history included a reported common cold the week prior, hyperlipidemia, and hypertension, for which he took metoprolol, simvastatin, aspirin, and clopidogrel. He denied oral lesions and medication changes. He was afebrile and did not experience dietary changes, weight loss, or fatigue. He recently returned from travel to the Dominican Republic.

Physical examination revealed tender, well demarcated, pink to violaceous, pseudovesicular papules and plaques on the palms and dorsal hands (Figure 1), the posterior scalp, left ear, proximal left arm, and back. Pink, juicy, targetoid papules were also found on the scalp, back, and left arm. There was no evidence of lymphadenopathy. Laboratory test results revealed an elevated white blood cell count (11,500/µL [reference range, 3800-10,800/µL]), absolute neutrophil count (8073/µL [reference range, 1500–7800/µL]), and eosinophil count (610/µL [reference range, 15–500/µL]). These results indicated leukocytosis with neutrophilia and mild eosinophilia. The patient also was anemic (hemoglobin, 11.5 g/dL [reference range, 13.2–17.1 g/dL]; hematocrit, 35.1% [reference range, 38.5%–50%]). Urine testing revealed altered renal function (serum creatinine, 2.42 mg/dL [reference range, 0.7–1.1 mg/dL]; blood urea nitrogen, 34 mg/dL [reference range, 7–25 mg/dL]; glomerular filtration rate, 4 mL/min/1.73 m² (reference range, ≥60 mL/min/1.73 m²]), suggesting stage 4 chronic kidney disease. Urinalysis showed mild hematuria and proteinuria.

In our patient, the observed clinical and histological findings were consistent with a diagnosis of SS,^2,10 specifically tender erythematous plaques of sudden onset, fast response to systemic corticosteroid therapy, a dermal neutrophilic infiltrate without evidence of leukocytoclastic vasculitis, and leukocytosis greater than 8000/µL with more than 70% neutrophils. He also exhibited targetoid lesions, which have been reported in 7% to 12% of SS patients.^10,11

The predominant cells involved in the dermis of SS lesions are mature neutrophils; however, eosinophils have been observed in small numbers within dermal infiltrates in skin lesions of patients with either classical SS or drug-induced dermatosis.² In 2 studies of cases of SS (N=73 and N=31), eosinophils were reported in 35% and 41% of skin biopsies, respectively.^4,5 Nevertheless, cases with dense eosinophilic infiltrates are rare. Furthermore, Masuda et al¹² reported a case of eosinophil-rich SS in a 29-year-old woman after treatment of an upper respiratory tract infection with an antibiotic, and Soon et al¹³ described an eosinophil-rich case of SS in the setting of new-onset enteropathy-associated T-cell lymphoma.

Our patient was considered to have classical SS because he had an episode of an upper respiratory tract infection 1 week prior to onset of clinical manifestations. The histologic finding of numerous eosinophils in our case was unusual for idiopathic SS. This finding might suggest a drug hypersensitivity reaction, but the lack of any change in the patient’s long-term medication list and the lack of any other episodes made a diagnosis of drug-induced SS less likely in our patient.

Eosinophilic dermatosis of hematologic malignancy is a rare cutaneous condition in which nodules, pruritic papules, and vesicles arise in patients with a hematologic malignancy, such as chronic lymphocytic leukemia and mantle cell lymphoma,¹³ in which a deep perivascular lymphocytic infiltrate and numerous eosinophils are observed. Malignancy was ruled out in our patient because of the lack of characteristic abnormalities in blood testing, the fast response to corticosteroid therapy, and the lack of recurrence posttreatment or additional systemic concerns.

The typical pathology findings of SS consist of mature neutrophils found in the dermis without evidence of leukocytoclastic vasculitis. Eosinophil-rich infiltration, however rare, has been reported in SS. This report highlights a case of classical SS with a particularly dense eosinophilic infiltrate, which could be mistaken for other eosinophilic dermatoses. Dermatologists should be aware of the possibility of marked eosinophilic infiltration in all subtypes of this disorder.

The Diagnosis: Dermatofibroma With Sebaceous Induction 

The biopsy of the lesion revealed a fibrohistiocytic dermal pattern with overlying benign epidermal and sebaceous hyperplasia with a proliferation of fibroblasts in the dermis. Other sections revealed hyperplastic sebaceous glands of the superficial and mid dermis. These findings were suggestive of a dermatofibroma (DF) that had induced epidermal and sebaceous hyperplasia.  

Dermatofibromas are common benign fibrous soft tissue growths that account for approximately 3% of dermatopathology specimens.¹ The etiology of DFs is unknown; however, they are thought to arise from sites of prior trauma or arthropod bites. Multiple or eruptive DFs have been reported in patients with lupus and atopic dermatitis.² They commonly appear as round firm nodules measuring less than 1 cm in diameter on the extremities of young adults. Eruptive dermatofibromas also have been reported in human immunodeficiency virus-positive and immunosuppressed patients.^3,4 On physical examination, gently pinching the lesion causes a downward movement known as the "dimple sign." If left undisturbed, DFs persist but may undergo partial regression, especially in the center; they also may be excised if symptomatic.  

The clinical differential for this papule included a scar and sebaceous hyperplasia. The lack of history of skin cancer or prior procedure made a scar less likely. Sebaceous glands are less prominent on the shoulders, making sebaceous hyperplasia less likely, though dermoscopy showed pale yellow lobules. Sebaceous adenomas most commonly are seen on the head or neck and present as a flesh-colored papule. Sebaceous induction by DFs is rare but has been reported in the literature.^5,6 

The histology of DFs is described as a nodular proliferation of spindle-shaped fibroblasts and myofibroblasts with short intersecting fascicles. A predilection for sebaceous induction from an underlying DF on the shoulder has been reported.⁵ Sebaceous differentiation has been reported in 16% to 31.6% of DFs.^5,6 Seborrheic keratosis-like epidermal hyperplasia frequently has been seen in DFs with sebaceous induction in comparison to DFs without sebaceous induction.⁵ Immunohistochemical stains are important to help differentiate DF from dermatofibrosarcoma protuberans, especially when approaching the subcutis. Dermatofibromas stain positive for factor XIIIa and negative for CD34, whereas dermatofibrosarcoma protuberans stain negative for factor XIIIa and positive for CD34.⁷ Dermatofibromas also demonstrate positive immunostaining for vimentin, stromelysin 3,⁸ muscle-specific actin, and CD68.  

The Diagnosis: Dermatofibroma With Sebaceous Induction 

The biopsy of the lesion revealed a fibrohistiocytic dermal pattern with overlying benign epidermal and sebaceous hyperplasia with a proliferation of fibroblasts in the dermis. Other sections revealed hyperplastic sebaceous glands of the superficial and mid dermis. These findings were suggestive of a dermatofibroma (DF) that had induced epidermal and sebaceous hyperplasia.  

Dermatofibromas are common benign fibrous soft tissue growths that account for approximately 3% of dermatopathology specimens.¹ The etiology of DFs is unknown; however, they are thought to arise from sites of prior trauma or arthropod bites. Multiple or eruptive DFs have been reported in patients with lupus and atopic dermatitis.² They commonly appear as round firm nodules measuring less than 1 cm in diameter on the extremities of young adults. Eruptive dermatofibromas also have been reported in human immunodeficiency virus-positive and immunosuppressed patients.^3,4 On physical examination, gently pinching the lesion causes a downward movement known as the "dimple sign." If left undisturbed, DFs persist but may undergo partial regression, especially in the center; they also may be excised if symptomatic.  

The clinical differential for this papule included a scar and sebaceous hyperplasia. The lack of history of skin cancer or prior procedure made a scar less likely. Sebaceous glands are less prominent on the shoulders, making sebaceous hyperplasia less likely, though dermoscopy showed pale yellow lobules. Sebaceous adenomas most commonly are seen on the head or neck and present as a flesh-colored papule. Sebaceous induction by DFs is rare but has been reported in the literature.^5,6 

The histology of DFs is described as a nodular proliferation of spindle-shaped fibroblasts and myofibroblasts with short intersecting fascicles. A predilection for sebaceous induction from an underlying DF on the shoulder has been reported.⁵ Sebaceous differentiation has been reported in 16% to 31.6% of DFs.^5,6 Seborrheic keratosis-like epidermal hyperplasia frequently has been seen in DFs with sebaceous induction in comparison to DFs without sebaceous induction.⁵ Immunohistochemical stains are important to help differentiate DF from dermatofibrosarcoma protuberans, especially when approaching the subcutis. Dermatofibromas stain positive for factor XIIIa and negative for CD34, whereas dermatofibrosarcoma protuberans stain negative for factor XIIIa and positive for CD34.⁷ Dermatofibromas also demonstrate positive immunostaining for vimentin, stromelysin 3,⁸ muscle-specific actin, and CD68.  

The Diagnosis: Dermatofibroma With Sebaceous Induction 

The biopsy of the lesion revealed a fibrohistiocytic dermal pattern with overlying benign epidermal and sebaceous hyperplasia with a proliferation of fibroblasts in the dermis. Other sections revealed hyperplastic sebaceous glands of the superficial and mid dermis. These findings were suggestive of a dermatofibroma (DF) that had induced epidermal and sebaceous hyperplasia.  

Dermatofibromas are common benign fibrous soft tissue growths that account for approximately 3% of dermatopathology specimens.¹ The etiology of DFs is unknown; however, they are thought to arise from sites of prior trauma or arthropod bites. Multiple or eruptive DFs have been reported in patients with lupus and atopic dermatitis.² They commonly appear as round firm nodules measuring less than 1 cm in diameter on the extremities of young adults. Eruptive dermatofibromas also have been reported in human immunodeficiency virus-positive and immunosuppressed patients.^3,4 On physical examination, gently pinching the lesion causes a downward movement known as the "dimple sign." If left undisturbed, DFs persist but may undergo partial regression, especially in the center; they also may be excised if symptomatic.  

The clinical differential for this papule included a scar and sebaceous hyperplasia. The lack of history of skin cancer or prior procedure made a scar less likely. Sebaceous glands are less prominent on the shoulders, making sebaceous hyperplasia less likely, though dermoscopy showed pale yellow lobules. Sebaceous adenomas most commonly are seen on the head or neck and present as a flesh-colored papule. Sebaceous induction by DFs is rare but has been reported in the literature.^5,6 

The histology of DFs is described as a nodular proliferation of spindle-shaped fibroblasts and myofibroblasts with short intersecting fascicles. A predilection for sebaceous induction from an underlying DF on the shoulder has been reported.⁵ Sebaceous differentiation has been reported in 16% to 31.6% of DFs.^5,6 Seborrheic keratosis-like epidermal hyperplasia frequently has been seen in DFs with sebaceous induction in comparison to DFs without sebaceous induction.⁵ Immunohistochemical stains are important to help differentiate DF from dermatofibrosarcoma protuberans, especially when approaching the subcutis. Dermatofibromas stain positive for factor XIIIa and negative for CD34, whereas dermatofibrosarcoma protuberans stain negative for factor XIIIa and positive for CD34.⁷ Dermatofibromas also demonstrate positive immunostaining for vimentin, stromelysin 3,⁸ muscle-specific actin, and CD68.  

The Diagnosis: Hypergranulotic Dyscornification 

Hypergranulotic dyscornification (HD) is a rarely reported reaction pattern present in benign solitary keratoses with only few reports to date. It may be an underrecognized reaction pattern based on the paucity of reported cases as well as the histologic similarities to other entities. It has been hypothesized that this pattern reflects an underlying keratin mutation or disorder of keratinization.¹ 

Clinically, HD most commonly presents as a waxy, tan-colored, solitary keratosis generally found on the lower limbs, trunk, or back in individuals aged 20 to 60 years.^1,2 Histopathology shows marked hyperkeratosis, papillomatosis, and clumped basophilic keratohyalin granules within the corneocytes with digitated epidermal hyperplasia. There is abnormal cornification across the entire lesion with papillomatosis and marked hypergranulosis.³ There often are homogeneous orthokeratotic mounds of large, dull, eosinophilic-staining anucleate keratinocytes that are sharply demarcated from the thickened granular layer.^1,2 Within the spinous, granular, and corneal layers, there is a pale, gray-staining, basophilic, cytoplasmic substance intercellularly.¹ 

Histopathologically, HD may be mistaken for several other entities both benign and malignant.¹ Epidermolytic hyperkeratosis can be a genetic disorder, an incidental finding in a variety of skin conditions, or an isolated lesion.⁴ The genetic syndrome, caused by mutation in keratins 1 or 10, clinically presents with hyperkeratosis, erosions, blisters, and thickening of the epidermis, often with a corrugated appearance. Epidermal nevi findings often are seen in conjunction with histologic changes of epidermolytic hyperkeratosis caused by mutation. Solitary lesions also can resemble seborrheic keratosis or verruca. In all examples of epidermolytic hyperkeratosis, the histopathologic findings are identical.⁴ The granular layer is thickened, and coarse keratohyalin granules aggregate in the suprabasal cells.⁵ There is acantholysis with perinuclear vacuolization in the spinous and granular layers with characteristic pale cytoplasmic areas devoid of keratin filaments (Figure 1). The basal layer may be hyperproliferative.⁵ 

Irritated seborrheic keratosis presents as an exophytic, waxy, dark, sharply demarcated plaque with a stuck-on appearance.⁶ There is visible keratinization with comedolike openings, fissures and ridges, and scale; it also can contain milialike cysts. Histopathologically there is papillomatosis with prominent rete ridges, often including keratin pseudohorn cysts and squamous eddies. Enlarged capillaries can be seen in the dermal papillae. There is normal cytology with benign sheets of basaloid cells (Figure 2).⁷ Activating mutation in fibroblast growth factor receptor 3 leads to the growth and thickness of the epidermis that has been identified in these benign lesions.⁸ 

Verruca plana appears as a flesh-colored or reddish, warty, flat-topped papule that often forms clusters. Histopathologically it shows prominent hypergranulosis, thickened stratum spinosum, and vacuolized keratinocytes.⁹ The nuclei demonstrate a characteristic cytopathic effect of the virion, blurring the nuclear chromatin due to viral particle accumulation, known as koilocytes (Figure 3). The cause is the double-stranded DNA human papillomavirus types 2, 3, and 10.¹⁰

Bowen disease is a form of squamous cell carcinoma in situ characterized by an enlarging, well-demarcated, erythematous plaque with an irregular border and crusting or scaling. Histopathology reveals pleomorphic epidermal keratinization that becomes incorporated in the stratum corneum as parakeratotic nuclei. There is acanthosis, elongation of the rete ridges, and disorganized keratinocytes with atypia.¹¹ The granular and spinous layers show an atypical honeycomb pattern with atypical cellular morphology (Figure 4).¹² Bowen disease is a malignant lesion commonly found in older adults on sun-exposed skin that can evolve into invasive squamous cell carcinoma. 

The Diagnosis: Hypergranulotic Dyscornification 

Hypergranulotic dyscornification (HD) is a rarely reported reaction pattern present in benign solitary keratoses with only few reports to date. It may be an underrecognized reaction pattern based on the paucity of reported cases as well as the histologic similarities to other entities. It has been hypothesized that this pattern reflects an underlying keratin mutation or disorder of keratinization.¹ 

Clinically, HD most commonly presents as a waxy, tan-colored, solitary keratosis generally found on the lower limbs, trunk, or back in individuals aged 20 to 60 years.^1,2 Histopathology shows marked hyperkeratosis, papillomatosis, and clumped basophilic keratohyalin granules within the corneocytes with digitated epidermal hyperplasia. There is abnormal cornification across the entire lesion with papillomatosis and marked hypergranulosis.³ There often are homogeneous orthokeratotic mounds of large, dull, eosinophilic-staining anucleate keratinocytes that are sharply demarcated from the thickened granular layer.^1,2 Within the spinous, granular, and corneal layers, there is a pale, gray-staining, basophilic, cytoplasmic substance intercellularly.¹ 

Histopathologically, HD may be mistaken for several other entities both benign and malignant.¹ Epidermolytic hyperkeratosis can be a genetic disorder, an incidental finding in a variety of skin conditions, or an isolated lesion.⁴ The genetic syndrome, caused by mutation in keratins 1 or 10, clinically presents with hyperkeratosis, erosions, blisters, and thickening of the epidermis, often with a corrugated appearance. Epidermal nevi findings often are seen in conjunction with histologic changes of epidermolytic hyperkeratosis caused by mutation. Solitary lesions also can resemble seborrheic keratosis or verruca. In all examples of epidermolytic hyperkeratosis, the histopathologic findings are identical.⁴ The granular layer is thickened, and coarse keratohyalin granules aggregate in the suprabasal cells.⁵ There is acantholysis with perinuclear vacuolization in the spinous and granular layers with characteristic pale cytoplasmic areas devoid of keratin filaments (Figure 1). The basal layer may be hyperproliferative.⁵ 

Irritated seborrheic keratosis presents as an exophytic, waxy, dark, sharply demarcated plaque with a stuck-on appearance.⁶ There is visible keratinization with comedolike openings, fissures and ridges, and scale; it also can contain milialike cysts. Histopathologically there is papillomatosis with prominent rete ridges, often including keratin pseudohorn cysts and squamous eddies. Enlarged capillaries can be seen in the dermal papillae. There is normal cytology with benign sheets of basaloid cells (Figure 2).⁷ Activating mutation in fibroblast growth factor receptor 3 leads to the growth and thickness of the epidermis that has been identified in these benign lesions.⁸ 

Verruca plana appears as a flesh-colored or reddish, warty, flat-topped papule that often forms clusters. Histopathologically it shows prominent hypergranulosis, thickened stratum spinosum, and vacuolized keratinocytes.⁹ The nuclei demonstrate a characteristic cytopathic effect of the virion, blurring the nuclear chromatin due to viral particle accumulation, known as koilocytes (Figure 3). The cause is the double-stranded DNA human papillomavirus types 2, 3, and 10.¹⁰

Bowen disease is a form of squamous cell carcinoma in situ characterized by an enlarging, well-demarcated, erythematous plaque with an irregular border and crusting or scaling. Histopathology reveals pleomorphic epidermal keratinization that becomes incorporated in the stratum corneum as parakeratotic nuclei. There is acanthosis, elongation of the rete ridges, and disorganized keratinocytes with atypia.¹¹ The granular and spinous layers show an atypical honeycomb pattern with atypical cellular morphology (Figure 4).¹² Bowen disease is a malignant lesion commonly found in older adults on sun-exposed skin that can evolve into invasive squamous cell carcinoma. 

The Diagnosis: Hypergranulotic Dyscornification 

Hypergranulotic dyscornification (HD) is a rarely reported reaction pattern present in benign solitary keratoses with only few reports to date. It may be an underrecognized reaction pattern based on the paucity of reported cases as well as the histologic similarities to other entities. It has been hypothesized that this pattern reflects an underlying keratin mutation or disorder of keratinization.¹ 

Clinically, HD most commonly presents as a waxy, tan-colored, solitary keratosis generally found on the lower limbs, trunk, or back in individuals aged 20 to 60 years.^1,2 Histopathology shows marked hyperkeratosis, papillomatosis, and clumped basophilic keratohyalin granules within the corneocytes with digitated epidermal hyperplasia. There is abnormal cornification across the entire lesion with papillomatosis and marked hypergranulosis.³ There often are homogeneous orthokeratotic mounds of large, dull, eosinophilic-staining anucleate keratinocytes that are sharply demarcated from the thickened granular layer.^1,2 Within the spinous, granular, and corneal layers, there is a pale, gray-staining, basophilic, cytoplasmic substance intercellularly.¹ 

Histopathologically, HD may be mistaken for several other entities both benign and malignant.¹ Epidermolytic hyperkeratosis can be a genetic disorder, an incidental finding in a variety of skin conditions, or an isolated lesion.⁴ The genetic syndrome, caused by mutation in keratins 1 or 10, clinically presents with hyperkeratosis, erosions, blisters, and thickening of the epidermis, often with a corrugated appearance. Epidermal nevi findings often are seen in conjunction with histologic changes of epidermolytic hyperkeratosis caused by mutation. Solitary lesions also can resemble seborrheic keratosis or verruca. In all examples of epidermolytic hyperkeratosis, the histopathologic findings are identical.⁴ The granular layer is thickened, and coarse keratohyalin granules aggregate in the suprabasal cells.⁵ There is acantholysis with perinuclear vacuolization in the spinous and granular layers with characteristic pale cytoplasmic areas devoid of keratin filaments (Figure 1). The basal layer may be hyperproliferative.⁵ 

Irritated seborrheic keratosis presents as an exophytic, waxy, dark, sharply demarcated plaque with a stuck-on appearance.⁶ There is visible keratinization with comedolike openings, fissures and ridges, and scale; it also can contain milialike cysts. Histopathologically there is papillomatosis with prominent rete ridges, often including keratin pseudohorn cysts and squamous eddies. Enlarged capillaries can be seen in the dermal papillae. There is normal cytology with benign sheets of basaloid cells (Figure 2).⁷ Activating mutation in fibroblast growth factor receptor 3 leads to the growth and thickness of the epidermis that has been identified in these benign lesions.⁸ 

Verruca plana appears as a flesh-colored or reddish, warty, flat-topped papule that often forms clusters. Histopathologically it shows prominent hypergranulosis, thickened stratum spinosum, and vacuolized keratinocytes.⁹ The nuclei demonstrate a characteristic cytopathic effect of the virion, blurring the nuclear chromatin due to viral particle accumulation, known as koilocytes (Figure 3). The cause is the double-stranded DNA human papillomavirus types 2, 3, and 10.¹⁰

Bowen disease is a form of squamous cell carcinoma in situ characterized by an enlarging, well-demarcated, erythematous plaque with an irregular border and crusting or scaling. Histopathology reveals pleomorphic epidermal keratinization that becomes incorporated in the stratum corneum as parakeratotic nuclei. There is acanthosis, elongation of the rete ridges, and disorganized keratinocytes with atypia.¹¹ The granular and spinous layers show an atypical honeycomb pattern with atypical cellular morphology (Figure 4).¹² Bowen disease is a malignant lesion commonly found in older adults on sun-exposed skin that can evolve into invasive squamous cell carcinoma. 

To the Editor:

Pseudoepitheliomatous hyperplasia (PEH) is an uncommon type of reactive epidermal proliferation that can occur from a variety of causes, including an underlying infection, inflammation, neoplastic condition, or trauma induced from tattooing.¹ Diagnosis can be challenging and requires clinicopathologic correlation, as PEH can mimic malignancy on histopathology.^2-4 Histologically, PEH shows irregular hyperplasia of the epidermis and adnexal epithelium, elongation of the rete ridges, and extension of the reactive proliferation into the dermis. Absence of cytologic atypia is key to the diagnosis of PEH, helping to distinguish it from squamous cell carcinoma and keratoacanthoma. Clinically, patients typically present with well-demarcated, erythematous, scaly plaques or nodules in reactive areas, which can be symptomatically pruritic.

A 48-year-old woman presented with scaly and crusted verrucous plaques of 2 months’ duration that were isolated to the areas of purple pigment within a tattoo on the right lower leg. The patient reported pruritus in the affected areas that occurred immediately after obtaining the tattoo, which was her first and only tattoo. She denied any pertinent medical history, including an absence of immunosuppression and autoimmune or chronic inflammatory diseases.

Physical examination revealed scaly and crusted plaques isolated to areas of purple tattoo pigment (Figure 1). Areas of red, green, black, and blue pigmentation within the tattoo were uninvolved. With the initial suspicion of allergic contact dermatitis, two 6-mm punch biopsies were taken from adjacent linear plaques on the right leg for histology and tissue culture. Histopathologic evaluation revealed dermal tattoo pigment with overlying PEH and was negative for signs of infection (Figure 2). Infectious stains such as periodic acid–Schiff, Grocott-Gomori methenamine-silver, and Gram stains were performed and found to be negative. In addition, culture for mycobacteria came back negative. Prurigo was on the differential; however, histopathologic changes were more compatible with a PEH reaction to the tattoo.

An increase in the popularity of tattooing has led to more reports of various tattoo skin reactions.^4-6 The differential diagnosis is broad for tattoo reactions and includes granulomatous inflammation, sarcoidosis, psoriasis (Köbner phenomenon), allergic contact dermatitis, lichen planus, morphealike reactions, squamous cell carcinoma, and keratoacanthoma,⁵ which makes clinicopathologic correlation essential for accurate diagnosis. Our case demonstrated the characteristic epithelial hyperplasia in the absence of cytologic atypia. In addition, the presence of mixed dermal inflammation histologically was noted in our patient.

We report an unusual case of PEH occurring secondary to purple tattoo pigment. Our report also demonstrates the clinical and symptomatic improvement of PEH that can be achieved through the use of intralesional corticosteroid therapy. Our patient represents a case of PEH reactive to tattooing with purple ink. Further research to elucidate the precise pathogenesis of PEH tattoo reactions would be helpful in identifying high-risk patients and determining the most efficacious treatments.

To the Editor:

Pseudoepitheliomatous hyperplasia (PEH) is an uncommon type of reactive epidermal proliferation that can occur from a variety of causes, including an underlying infection, inflammation, neoplastic condition, or trauma induced from tattooing.¹ Diagnosis can be challenging and requires clinicopathologic correlation, as PEH can mimic malignancy on histopathology.^2-4 Histologically, PEH shows irregular hyperplasia of the epidermis and adnexal epithelium, elongation of the rete ridges, and extension of the reactive proliferation into the dermis. Absence of cytologic atypia is key to the diagnosis of PEH, helping to distinguish it from squamous cell carcinoma and keratoacanthoma. Clinically, patients typically present with well-demarcated, erythematous, scaly plaques or nodules in reactive areas, which can be symptomatically pruritic.

A 48-year-old woman presented with scaly and crusted verrucous plaques of 2 months’ duration that were isolated to the areas of purple pigment within a tattoo on the right lower leg. The patient reported pruritus in the affected areas that occurred immediately after obtaining the tattoo, which was her first and only tattoo. She denied any pertinent medical history, including an absence of immunosuppression and autoimmune or chronic inflammatory diseases.

Physical examination revealed scaly and crusted plaques isolated to areas of purple tattoo pigment (Figure 1). Areas of red, green, black, and blue pigmentation within the tattoo were uninvolved. With the initial suspicion of allergic contact dermatitis, two 6-mm punch biopsies were taken from adjacent linear plaques on the right leg for histology and tissue culture. Histopathologic evaluation revealed dermal tattoo pigment with overlying PEH and was negative for signs of infection (Figure 2). Infectious stains such as periodic acid–Schiff, Grocott-Gomori methenamine-silver, and Gram stains were performed and found to be negative. In addition, culture for mycobacteria came back negative. Prurigo was on the differential; however, histopathologic changes were more compatible with a PEH reaction to the tattoo.

An increase in the popularity of tattooing has led to more reports of various tattoo skin reactions.^4-6 The differential diagnosis is broad for tattoo reactions and includes granulomatous inflammation, sarcoidosis, psoriasis (Köbner phenomenon), allergic contact dermatitis, lichen planus, morphealike reactions, squamous cell carcinoma, and keratoacanthoma,⁵ which makes clinicopathologic correlation essential for accurate diagnosis. Our case demonstrated the characteristic epithelial hyperplasia in the absence of cytologic atypia. In addition, the presence of mixed dermal inflammation histologically was noted in our patient.

We report an unusual case of PEH occurring secondary to purple tattoo pigment. Our report also demonstrates the clinical and symptomatic improvement of PEH that can be achieved through the use of intralesional corticosteroid therapy. Our patient represents a case of PEH reactive to tattooing with purple ink. Further research to elucidate the precise pathogenesis of PEH tattoo reactions would be helpful in identifying high-risk patients and determining the most efficacious treatments.

To the Editor:

Pseudoepitheliomatous hyperplasia (PEH) is an uncommon type of reactive epidermal proliferation that can occur from a variety of causes, including an underlying infection, inflammation, neoplastic condition, or trauma induced from tattooing.¹ Diagnosis can be challenging and requires clinicopathologic correlation, as PEH can mimic malignancy on histopathology.^2-4 Histologically, PEH shows irregular hyperplasia of the epidermis and adnexal epithelium, elongation of the rete ridges, and extension of the reactive proliferation into the dermis. Absence of cytologic atypia is key to the diagnosis of PEH, helping to distinguish it from squamous cell carcinoma and keratoacanthoma. Clinically, patients typically present with well-demarcated, erythematous, scaly plaques or nodules in reactive areas, which can be symptomatically pruritic.

A 48-year-old woman presented with scaly and crusted verrucous plaques of 2 months’ duration that were isolated to the areas of purple pigment within a tattoo on the right lower leg. The patient reported pruritus in the affected areas that occurred immediately after obtaining the tattoo, which was her first and only tattoo. She denied any pertinent medical history, including an absence of immunosuppression and autoimmune or chronic inflammatory diseases.

Physical examination revealed scaly and crusted plaques isolated to areas of purple tattoo pigment (Figure 1). Areas of red, green, black, and blue pigmentation within the tattoo were uninvolved. With the initial suspicion of allergic contact dermatitis, two 6-mm punch biopsies were taken from adjacent linear plaques on the right leg for histology and tissue culture. Histopathologic evaluation revealed dermal tattoo pigment with overlying PEH and was negative for signs of infection (Figure 2). Infectious stains such as periodic acid–Schiff, Grocott-Gomori methenamine-silver, and Gram stains were performed and found to be negative. In addition, culture for mycobacteria came back negative. Prurigo was on the differential; however, histopathologic changes were more compatible with a PEH reaction to the tattoo.

An increase in the popularity of tattooing has led to more reports of various tattoo skin reactions.^4-6 The differential diagnosis is broad for tattoo reactions and includes granulomatous inflammation, sarcoidosis, psoriasis (Köbner phenomenon), allergic contact dermatitis, lichen planus, morphealike reactions, squamous cell carcinoma, and keratoacanthoma,⁵ which makes clinicopathologic correlation essential for accurate diagnosis. Our case demonstrated the characteristic epithelial hyperplasia in the absence of cytologic atypia. In addition, the presence of mixed dermal inflammation histologically was noted in our patient.

We report an unusual case of PEH occurring secondary to purple tattoo pigment. Our report also demonstrates the clinical and symptomatic improvement of PEH that can be achieved through the use of intralesional corticosteroid therapy. Our patient represents a case of PEH reactive to tattooing with purple ink. Further research to elucidate the precise pathogenesis of PEH tattoo reactions would be helpful in identifying high-risk patients and determining the most efficacious treatments.