Dermatopathology

To the Editor:

Focal palmoplantar keratoderma and gingival keratosis (FPGK)(Online Mendelian Inheritance in Man [OMIM] 148730) is a rare autosomal-dominant syndrome featuring focal, pressure-related, painful palmoplantar keratoderma and gingival hyperkeratosis presenting as leukokeratosis. Focal palmoplantar keratoderma and gingival keratosis was first defined by Gorlin¹ in 1976. Since then, only a few cases have been reported, but no causative mutations have been identified.²

Focal pressure-related palmoplantar keratoderma (PPK) and oral hyperkeratosis also are seen in pachyonychia congenita (PC)(OMIM 167200, 615726, 615728, 167210), a rare autosomal-dominant disorder of keratinization characterized by PPK and nail dystrophy. Patients with PC often present with plantar pain; more variable features include oral leukokeratosis, follicular hyperkeratosis, pilosebaceous and epidermal inclusion cysts, hoarseness, hyperhidrosis, and natal teeth. Pachyonychia congenita is caused by mutation in keratin genes KRT6A, KRT6B, KRT16, or KRT17.

Focal palmoplantar keratoderma and gingival keratosis as well as PC are distinct from other forms of PPK with gingival involvement such as Papillon-Lefèvre syndrome (OMIM 245000) and Olmsted syndrome (OMIM 614594). Papillon-Lefèvre syndrome is a rare autosomal-recessive disorder caused by mutations in the cathepsin C, CTSC, gene that exhibits erythematous, diffuse, transgradient PPK and early severe periodontitis. Olmsted syndrome is caused by autosomal-dominant gene mutations in transient receptor potential cation channel, subfamily V, member 3, TRPV3, and is characterized by severe bilateral transgradient PPK with leukoplakia of the tongue and buccal mucosa but also usually exhibits marked periorificial keratotic plaques, which facilitate exclusion of other phenotypically similar syndromes.³

Despite the common features of FPGK and PC, they are considered distinct disorders due to absence of nail changes in FPGK and no prior evidence of a common genetic cause. We present a patient with familial FPGK found by whole exome sequencing to be caused by a mutation in KRT16.

The proband was a 57-year-old man born to unrelated parents (Figure 1). He had no skin problems at birth, and his development was normal. He had painful focal keratoderma since childhood that were most prominent at pressure points on the soles and toes (Figure 2A), in addition to gingival hyperkeratosis and oral leukokeratosis (Figure 2B). He had no associated abnormalities of the skin, hair, or teeth and no nail findings (Figure 2C). He reported that his father and 2 of his 3 sisters were affected with similar symptoms. A punch biopsy of the right fifth toe was consistent with verrucous epidermal hyperplasia with perinuclear keratinization in the spinous layer (Figure 3A). A gingival biopsy showed perinuclear eosinophilic globules and basophilic stranding in the cytoplasm (Figure 3B). His older sister had more severe and painful focal keratoderma of the soles, punctate keratoderma of the palms, gingival hyperkeratosis, and leukokeratosis of the tongue.

Whole exome sequencing of the proband revealed a heterozygous missense mutation in KRT16 (c.380G>A, p.R127H, rs57424749). Sanger sequencing confirmed this mutation and showed that it was heterozygous in both of his affected sisters and absent in his unaffected niece (Figure 1). The patient was treated with topical and systemic retinoids, keratolytics, and mechanical removal to moderate effect, with noted improvement in the appearance and associated pain of the plantar keratoderma.

Phenotypic heterogeneity is common in PC, though PC due to KRT6A mutations demonstrates more severe nail disease with oral lesions, cysts, and follicular hyperkeratosis, while PC caused by KRT16 mutations generally presents with more extensive and painful PPK.⁴KRT16 mutations affecting p.R127 are frequent causes of PC, and genotype-phenotype correlations have been observed. Individuals with p.R127P mutations exhibit more severe disease with earlier age of onset, more extensive nail involvement and oral leukokeratosis, and greater impact on daily quality of life than in individuals with p.R127C mutations.⁵ Cases of PC with KRT16 p.R127S and p.R127G mutations also have been observed. The KRT16 c.380G>A, p.R127H mutation we documented has been reported in one kindred with PC who presented with PPK, oral leukokeratosis, toenail thickening, and pilosebaceous and follicular hyperkeratosis.⁶

Although patients with FPGK lack the thickening of fingernails and/or toenails considered a defining feature of PC, the disorders otherwise are phenotypically similar, suggesting the possibility of common pathogenesis. One linkage study of familial FPGK excluded genetic intervals containing type I and type II keratins but was limited to a single small kindred.² This study and our data together suggest that, similar to PC, there are multiple genes in which mutations cause FPGK.

Murine Krt16 knockouts show distinct phenotypes depending on the mouse strain in which they are propagated, ranging from perinatal lethality to differences in the severity of oral and PPK lesions.⁷ These observations provide evidence that additional genetic variants contribute to Krt16 phenotypes in mice and suggest the same could be true for humans.

We propose that some cases of FPGK are due to mutations in KRT16 and thus share a genetic pathogenesis with PC, underscoring the utility of whole exome sequencing in providing genetic diagnoses for disorders that are genetically and clinically heterogeneous. Further biologic investigation of phenotypes caused by KRT16 mutation may reveal respective contributions of additional genetic variation and environmental effects to the variable clinical presentations.

To the Editor:

Focal palmoplantar keratoderma and gingival keratosis (FPGK)(Online Mendelian Inheritance in Man [OMIM] 148730) is a rare autosomal-dominant syndrome featuring focal, pressure-related, painful palmoplantar keratoderma and gingival hyperkeratosis presenting as leukokeratosis. Focal palmoplantar keratoderma and gingival keratosis was first defined by Gorlin¹ in 1976. Since then, only a few cases have been reported, but no causative mutations have been identified.²

Focal pressure-related palmoplantar keratoderma (PPK) and oral hyperkeratosis also are seen in pachyonychia congenita (PC)(OMIM 167200, 615726, 615728, 167210), a rare autosomal-dominant disorder of keratinization characterized by PPK and nail dystrophy. Patients with PC often present with plantar pain; more variable features include oral leukokeratosis, follicular hyperkeratosis, pilosebaceous and epidermal inclusion cysts, hoarseness, hyperhidrosis, and natal teeth. Pachyonychia congenita is caused by mutation in keratin genes KRT6A, KRT6B, KRT16, or KRT17.

Focal palmoplantar keratoderma and gingival keratosis as well as PC are distinct from other forms of PPK with gingival involvement such as Papillon-Lefèvre syndrome (OMIM 245000) and Olmsted syndrome (OMIM 614594). Papillon-Lefèvre syndrome is a rare autosomal-recessive disorder caused by mutations in the cathepsin C, CTSC, gene that exhibits erythematous, diffuse, transgradient PPK and early severe periodontitis. Olmsted syndrome is caused by autosomal-dominant gene mutations in transient receptor potential cation channel, subfamily V, member 3, TRPV3, and is characterized by severe bilateral transgradient PPK with leukoplakia of the tongue and buccal mucosa but also usually exhibits marked periorificial keratotic plaques, which facilitate exclusion of other phenotypically similar syndromes.³

Despite the common features of FPGK and PC, they are considered distinct disorders due to absence of nail changes in FPGK and no prior evidence of a common genetic cause. We present a patient with familial FPGK found by whole exome sequencing to be caused by a mutation in KRT16.

The proband was a 57-year-old man born to unrelated parents (Figure 1). He had no skin problems at birth, and his development was normal. He had painful focal keratoderma since childhood that were most prominent at pressure points on the soles and toes (Figure 2A), in addition to gingival hyperkeratosis and oral leukokeratosis (Figure 2B). He had no associated abnormalities of the skin, hair, or teeth and no nail findings (Figure 2C). He reported that his father and 2 of his 3 sisters were affected with similar symptoms. A punch biopsy of the right fifth toe was consistent with verrucous epidermal hyperplasia with perinuclear keratinization in the spinous layer (Figure 3A). A gingival biopsy showed perinuclear eosinophilic globules and basophilic stranding in the cytoplasm (Figure 3B). His older sister had more severe and painful focal keratoderma of the soles, punctate keratoderma of the palms, gingival hyperkeratosis, and leukokeratosis of the tongue.

Whole exome sequencing of the proband revealed a heterozygous missense mutation in KRT16 (c.380G>A, p.R127H, rs57424749). Sanger sequencing confirmed this mutation and showed that it was heterozygous in both of his affected sisters and absent in his unaffected niece (Figure 1). The patient was treated with topical and systemic retinoids, keratolytics, and mechanical removal to moderate effect, with noted improvement in the appearance and associated pain of the plantar keratoderma.

Phenotypic heterogeneity is common in PC, though PC due to KRT6A mutations demonstrates more severe nail disease with oral lesions, cysts, and follicular hyperkeratosis, while PC caused by KRT16 mutations generally presents with more extensive and painful PPK.⁴KRT16 mutations affecting p.R127 are frequent causes of PC, and genotype-phenotype correlations have been observed. Individuals with p.R127P mutations exhibit more severe disease with earlier age of onset, more extensive nail involvement and oral leukokeratosis, and greater impact on daily quality of life than in individuals with p.R127C mutations.⁵ Cases of PC with KRT16 p.R127S and p.R127G mutations also have been observed. The KRT16 c.380G>A, p.R127H mutation we documented has been reported in one kindred with PC who presented with PPK, oral leukokeratosis, toenail thickening, and pilosebaceous and follicular hyperkeratosis.⁶

Although patients with FPGK lack the thickening of fingernails and/or toenails considered a defining feature of PC, the disorders otherwise are phenotypically similar, suggesting the possibility of common pathogenesis. One linkage study of familial FPGK excluded genetic intervals containing type I and type II keratins but was limited to a single small kindred.² This study and our data together suggest that, similar to PC, there are multiple genes in which mutations cause FPGK.

Murine Krt16 knockouts show distinct phenotypes depending on the mouse strain in which they are propagated, ranging from perinatal lethality to differences in the severity of oral and PPK lesions.⁷ These observations provide evidence that additional genetic variants contribute to Krt16 phenotypes in mice and suggest the same could be true for humans.

We propose that some cases of FPGK are due to mutations in KRT16 and thus share a genetic pathogenesis with PC, underscoring the utility of whole exome sequencing in providing genetic diagnoses for disorders that are genetically and clinically heterogeneous. Further biologic investigation of phenotypes caused by KRT16 mutation may reveal respective contributions of additional genetic variation and environmental effects to the variable clinical presentations.

To the Editor:

Focal palmoplantar keratoderma and gingival keratosis (FPGK)(Online Mendelian Inheritance in Man [OMIM] 148730) is a rare autosomal-dominant syndrome featuring focal, pressure-related, painful palmoplantar keratoderma and gingival hyperkeratosis presenting as leukokeratosis. Focal palmoplantar keratoderma and gingival keratosis was first defined by Gorlin¹ in 1976. Since then, only a few cases have been reported, but no causative mutations have been identified.²

Focal pressure-related palmoplantar keratoderma (PPK) and oral hyperkeratosis also are seen in pachyonychia congenita (PC)(OMIM 167200, 615726, 615728, 167210), a rare autosomal-dominant disorder of keratinization characterized by PPK and nail dystrophy. Patients with PC often present with plantar pain; more variable features include oral leukokeratosis, follicular hyperkeratosis, pilosebaceous and epidermal inclusion cysts, hoarseness, hyperhidrosis, and natal teeth. Pachyonychia congenita is caused by mutation in keratin genes KRT6A, KRT6B, KRT16, or KRT17.

Focal palmoplantar keratoderma and gingival keratosis as well as PC are distinct from other forms of PPK with gingival involvement such as Papillon-Lefèvre syndrome (OMIM 245000) and Olmsted syndrome (OMIM 614594). Papillon-Lefèvre syndrome is a rare autosomal-recessive disorder caused by mutations in the cathepsin C, CTSC, gene that exhibits erythematous, diffuse, transgradient PPK and early severe periodontitis. Olmsted syndrome is caused by autosomal-dominant gene mutations in transient receptor potential cation channel, subfamily V, member 3, TRPV3, and is characterized by severe bilateral transgradient PPK with leukoplakia of the tongue and buccal mucosa but also usually exhibits marked periorificial keratotic plaques, which facilitate exclusion of other phenotypically similar syndromes.³

Despite the common features of FPGK and PC, they are considered distinct disorders due to absence of nail changes in FPGK and no prior evidence of a common genetic cause. We present a patient with familial FPGK found by whole exome sequencing to be caused by a mutation in KRT16.

The proband was a 57-year-old man born to unrelated parents (Figure 1). He had no skin problems at birth, and his development was normal. He had painful focal keratoderma since childhood that were most prominent at pressure points on the soles and toes (Figure 2A), in addition to gingival hyperkeratosis and oral leukokeratosis (Figure 2B). He had no associated abnormalities of the skin, hair, or teeth and no nail findings (Figure 2C). He reported that his father and 2 of his 3 sisters were affected with similar symptoms. A punch biopsy of the right fifth toe was consistent with verrucous epidermal hyperplasia with perinuclear keratinization in the spinous layer (Figure 3A). A gingival biopsy showed perinuclear eosinophilic globules and basophilic stranding in the cytoplasm (Figure 3B). His older sister had more severe and painful focal keratoderma of the soles, punctate keratoderma of the palms, gingival hyperkeratosis, and leukokeratosis of the tongue.

Whole exome sequencing of the proband revealed a heterozygous missense mutation in KRT16 (c.380G>A, p.R127H, rs57424749). Sanger sequencing confirmed this mutation and showed that it was heterozygous in both of his affected sisters and absent in his unaffected niece (Figure 1). The patient was treated with topical and systemic retinoids, keratolytics, and mechanical removal to moderate effect, with noted improvement in the appearance and associated pain of the plantar keratoderma.

Phenotypic heterogeneity is common in PC, though PC due to KRT6A mutations demonstrates more severe nail disease with oral lesions, cysts, and follicular hyperkeratosis, while PC caused by KRT16 mutations generally presents with more extensive and painful PPK.⁴KRT16 mutations affecting p.R127 are frequent causes of PC, and genotype-phenotype correlations have been observed. Individuals with p.R127P mutations exhibit more severe disease with earlier age of onset, more extensive nail involvement and oral leukokeratosis, and greater impact on daily quality of life than in individuals with p.R127C mutations.⁵ Cases of PC with KRT16 p.R127S and p.R127G mutations also have been observed. The KRT16 c.380G>A, p.R127H mutation we documented has been reported in one kindred with PC who presented with PPK, oral leukokeratosis, toenail thickening, and pilosebaceous and follicular hyperkeratosis.⁶

Although patients with FPGK lack the thickening of fingernails and/or toenails considered a defining feature of PC, the disorders otherwise are phenotypically similar, suggesting the possibility of common pathogenesis. One linkage study of familial FPGK excluded genetic intervals containing type I and type II keratins but was limited to a single small kindred.² This study and our data together suggest that, similar to PC, there are multiple genes in which mutations cause FPGK.

Murine Krt16 knockouts show distinct phenotypes depending on the mouse strain in which they are propagated, ranging from perinatal lethality to differences in the severity of oral and PPK lesions.⁷ These observations provide evidence that additional genetic variants contribute to Krt16 phenotypes in mice and suggest the same could be true for humans.

We propose that some cases of FPGK are due to mutations in KRT16 and thus share a genetic pathogenesis with PC, underscoring the utility of whole exome sequencing in providing genetic diagnoses for disorders that are genetically and clinically heterogeneous. Further biologic investigation of phenotypes caused by KRT16 mutation may reveal respective contributions of additional genetic variation and environmental effects to the variable clinical presentations.

The Diagnosis: Cutaneous Blastomycosis

A skin biopsy and fungal cultures confirmed the diagnosis of cutaneous blastomycosis. Grocott- Gomori methenamine-silver staining highlighted fungal organisms with refractile walls and broad-based budding consistent with cutaneous blastomycosis (Figure 1). The histopathologic specimen also demonstrated marked pseudoepitheliomatous hyperplasia (Figure 2A) with neutrophilic microabscesses (Figure 2B). Acid-fast bacillus and Fite staining were negative for bacterial organisms. A fungal culture was positive for Blastomyces dermatitidis. Urine and serum blastomycosis antigen were positive. Although Histoplasma serum antigen also was positive, this likely was from cross-reactivity. Chest radiography was negative for lung involvement, and the patient displayed no neurologic symptoms. He was started on oral itraconazole therapy for the treatment of cutaneous blastomycosis.

Blastomyces dermatitidis, the causative organism of blastomycosis, is endemic to the Ohio and Mississippi River valleys, Great Lakes region, and southeastern United States. It is a thermally dimorphic fungus found in soils that grows as a mold at 25 °C and yeast at 37 °C. Primary infection of the lungs—blastomycosis pneumonia—often is the only clinical manifestation¹; however, subsequent hematogenous dissemination to extrapulmonary sites such as the skin, bones, and genitourinary system can occur. Cutaneous blastomycosis, the most common extrapulmonary manifestation, typically follows pulmonary infection. In rare cases, it can occur from direct inoculation.^2,3 Skin lesions can occur anywhere but frequently are found on exposed surfaces of the head, neck, and extremities. Lesions classically present as verrucous crusting plaques with draining microabscesses. Violaceous nodules, ulcers, and pustules also may occur.¹

Diagnosis involves obtaining a thorough history of possible environmental exposures such as the patient’s geographic area of residence, occupation, and outdoor activities involving soil or decaying wood. Because blastomycosis can remain latent, remote exposures are relevant. Definitive diagnosis of cutaneous blastomycosis involves skin biopsy of the lesion with fungal culture, but the yeast’s distinctive thick wall and broad-based budding seen with periodic acid–Schiff or Grocott-Gomori methenamine-silver staining provides a rapid presumptive diagnosis.³ Pseudoepitheliomatous hyperplasia and microabscesses also are characteristic features.² Urine antigen testing for a component of the polysaccharide cell wall has a sensitivity of 93% but a lower specificity of 79% due to cross-reactivity with histoplasmosis.⁴ Treatment consists of itraconazole for mild to moderate blastomycosis or amphotericin B for those with severe disease or central nervous system involvement or those who are immunosuppressed.¹

The differential diagnosis for our patient’s lesion included infectious vs neoplastic etiologies. Histoplasma capsulatum, the dimorphic fungus that causes histoplasmosis, also is endemic to the Ohio and Mississippi River valleys. It is found in soil and droppings of some bats and birds such as chickens and pigeons. Similar to blastomycosis, the primary infection site most commonly is the lungs. It subsequently may disseminate to the skin or less commonly via direct inoculation of injured skin. It can present as papules, plaques, ulcers, purpura, or abscesses. Unlike blastomycosis, tissue biopsy of a cutaneous lesion reveals granuloma formation and distinctive oval, narrow-based budding yeast.⁵ Atypical mycobacteria are another source of infection to consider. For example, cutaneous Mycobacterium kansasii may present as papules and pustules forming verrucous or granulomatous plaques and ulceration. Histopathologic findings distinguishing mycobacterial infection from blastomycosis include granulomas and acid-fast bacilli in histiocytes.⁶

Noninfectious etiologies in the differential may include cutaneous squamous cell carcinoma or pemphigus vegetans. Squamous cell carcinoma may present with a broad range of clinical features—papules, plaques, or nodules with smooth, scaly, verrucous, or ulcerative secondary features all are possible presentations.⁷ Fairskinned individuals, such as our patient, would be at a higher risk in sun-damaged skin. Histologically, cutaneous squamous cell carcinoma is defined as an invasion of the dermis by neoplastic squamous epithelial cells in the form of cords, sheets, individual cells, nodules, or cystic structures.⁷ Pemphigus vegetans is the rarest variant of a group of autoimmune vesiculobullous diseases known as pemphigus. It can be differentiated from the most common variant—pemphigus vulgaris—by the presence of vegetative plaques in intertriginous areas. However, these verrucous vegetations can be misleading and make clinical diagnosis difficult. Histopathologic findings of hyperkeratosis, pseudoepitheliomatous hyperplasia, papillomatosis, and acantholysis with a suprabasal cleft would confirm the diagnosis.⁸

In summary, cutaneous blastomycosis classically presents as verrucous crusting plaques, as seen in our patient. It is important to conduct a thorough history for environmental exposures, but definitive diagnosis of cutaneous blastomycosis involves skin biopsy with fungal culture. Treatment depends on the severity of disease and organ involvement. Itraconazole would be appropriate for mild to moderate blastomycosis.

The Diagnosis: Cutaneous Blastomycosis

A skin biopsy and fungal cultures confirmed the diagnosis of cutaneous blastomycosis. Grocott- Gomori methenamine-silver staining highlighted fungal organisms with refractile walls and broad-based budding consistent with cutaneous blastomycosis (Figure 1). The histopathologic specimen also demonstrated marked pseudoepitheliomatous hyperplasia (Figure 2A) with neutrophilic microabscesses (Figure 2B). Acid-fast bacillus and Fite staining were negative for bacterial organisms. A fungal culture was positive for Blastomyces dermatitidis. Urine and serum blastomycosis antigen were positive. Although Histoplasma serum antigen also was positive, this likely was from cross-reactivity. Chest radiography was negative for lung involvement, and the patient displayed no neurologic symptoms. He was started on oral itraconazole therapy for the treatment of cutaneous blastomycosis.

Blastomyces dermatitidis, the causative organism of blastomycosis, is endemic to the Ohio and Mississippi River valleys, Great Lakes region, and southeastern United States. It is a thermally dimorphic fungus found in soils that grows as a mold at 25 °C and yeast at 37 °C. Primary infection of the lungs—blastomycosis pneumonia—often is the only clinical manifestation¹; however, subsequent hematogenous dissemination to extrapulmonary sites such as the skin, bones, and genitourinary system can occur. Cutaneous blastomycosis, the most common extrapulmonary manifestation, typically follows pulmonary infection. In rare cases, it can occur from direct inoculation.^2,3 Skin lesions can occur anywhere but frequently are found on exposed surfaces of the head, neck, and extremities. Lesions classically present as verrucous crusting plaques with draining microabscesses. Violaceous nodules, ulcers, and pustules also may occur.¹

Diagnosis involves obtaining a thorough history of possible environmental exposures such as the patient’s geographic area of residence, occupation, and outdoor activities involving soil or decaying wood. Because blastomycosis can remain latent, remote exposures are relevant. Definitive diagnosis of cutaneous blastomycosis involves skin biopsy of the lesion with fungal culture, but the yeast’s distinctive thick wall and broad-based budding seen with periodic acid–Schiff or Grocott-Gomori methenamine-silver staining provides a rapid presumptive diagnosis.³ Pseudoepitheliomatous hyperplasia and microabscesses also are characteristic features.² Urine antigen testing for a component of the polysaccharide cell wall has a sensitivity of 93% but a lower specificity of 79% due to cross-reactivity with histoplasmosis.⁴ Treatment consists of itraconazole for mild to moderate blastomycosis or amphotericin B for those with severe disease or central nervous system involvement or those who are immunosuppressed.¹

The differential diagnosis for our patient’s lesion included infectious vs neoplastic etiologies. Histoplasma capsulatum, the dimorphic fungus that causes histoplasmosis, also is endemic to the Ohio and Mississippi River valleys. It is found in soil and droppings of some bats and birds such as chickens and pigeons. Similar to blastomycosis, the primary infection site most commonly is the lungs. It subsequently may disseminate to the skin or less commonly via direct inoculation of injured skin. It can present as papules, plaques, ulcers, purpura, or abscesses. Unlike blastomycosis, tissue biopsy of a cutaneous lesion reveals granuloma formation and distinctive oval, narrow-based budding yeast.⁵ Atypical mycobacteria are another source of infection to consider. For example, cutaneous Mycobacterium kansasii may present as papules and pustules forming verrucous or granulomatous plaques and ulceration. Histopathologic findings distinguishing mycobacterial infection from blastomycosis include granulomas and acid-fast bacilli in histiocytes.⁶

Noninfectious etiologies in the differential may include cutaneous squamous cell carcinoma or pemphigus vegetans. Squamous cell carcinoma may present with a broad range of clinical features—papules, plaques, or nodules with smooth, scaly, verrucous, or ulcerative secondary features all are possible presentations.⁷ Fairskinned individuals, such as our patient, would be at a higher risk in sun-damaged skin. Histologically, cutaneous squamous cell carcinoma is defined as an invasion of the dermis by neoplastic squamous epithelial cells in the form of cords, sheets, individual cells, nodules, or cystic structures.⁷ Pemphigus vegetans is the rarest variant of a group of autoimmune vesiculobullous diseases known as pemphigus. It can be differentiated from the most common variant—pemphigus vulgaris—by the presence of vegetative plaques in intertriginous areas. However, these verrucous vegetations can be misleading and make clinical diagnosis difficult. Histopathologic findings of hyperkeratosis, pseudoepitheliomatous hyperplasia, papillomatosis, and acantholysis with a suprabasal cleft would confirm the diagnosis.⁸

In summary, cutaneous blastomycosis classically presents as verrucous crusting plaques, as seen in our patient. It is important to conduct a thorough history for environmental exposures, but definitive diagnosis of cutaneous blastomycosis involves skin biopsy with fungal culture. Treatment depends on the severity of disease and organ involvement. Itraconazole would be appropriate for mild to moderate blastomycosis.

The Diagnosis: Cutaneous Blastomycosis

A skin biopsy and fungal cultures confirmed the diagnosis of cutaneous blastomycosis. Grocott- Gomori methenamine-silver staining highlighted fungal organisms with refractile walls and broad-based budding consistent with cutaneous blastomycosis (Figure 1). The histopathologic specimen also demonstrated marked pseudoepitheliomatous hyperplasia (Figure 2A) with neutrophilic microabscesses (Figure 2B). Acid-fast bacillus and Fite staining were negative for bacterial organisms. A fungal culture was positive for Blastomyces dermatitidis. Urine and serum blastomycosis antigen were positive. Although Histoplasma serum antigen also was positive, this likely was from cross-reactivity. Chest radiography was negative for lung involvement, and the patient displayed no neurologic symptoms. He was started on oral itraconazole therapy for the treatment of cutaneous blastomycosis.

Blastomyces dermatitidis, the causative organism of blastomycosis, is endemic to the Ohio and Mississippi River valleys, Great Lakes region, and southeastern United States. It is a thermally dimorphic fungus found in soils that grows as a mold at 25 °C and yeast at 37 °C. Primary infection of the lungs—blastomycosis pneumonia—often is the only clinical manifestation¹; however, subsequent hematogenous dissemination to extrapulmonary sites such as the skin, bones, and genitourinary system can occur. Cutaneous blastomycosis, the most common extrapulmonary manifestation, typically follows pulmonary infection. In rare cases, it can occur from direct inoculation.^2,3 Skin lesions can occur anywhere but frequently are found on exposed surfaces of the head, neck, and extremities. Lesions classically present as verrucous crusting plaques with draining microabscesses. Violaceous nodules, ulcers, and pustules also may occur.¹

Diagnosis involves obtaining a thorough history of possible environmental exposures such as the patient’s geographic area of residence, occupation, and outdoor activities involving soil or decaying wood. Because blastomycosis can remain latent, remote exposures are relevant. Definitive diagnosis of cutaneous blastomycosis involves skin biopsy of the lesion with fungal culture, but the yeast’s distinctive thick wall and broad-based budding seen with periodic acid–Schiff or Grocott-Gomori methenamine-silver staining provides a rapid presumptive diagnosis.³ Pseudoepitheliomatous hyperplasia and microabscesses also are characteristic features.² Urine antigen testing for a component of the polysaccharide cell wall has a sensitivity of 93% but a lower specificity of 79% due to cross-reactivity with histoplasmosis.⁴ Treatment consists of itraconazole for mild to moderate blastomycosis or amphotericin B for those with severe disease or central nervous system involvement or those who are immunosuppressed.¹

The differential diagnosis for our patient’s lesion included infectious vs neoplastic etiologies. Histoplasma capsulatum, the dimorphic fungus that causes histoplasmosis, also is endemic to the Ohio and Mississippi River valleys. It is found in soil and droppings of some bats and birds such as chickens and pigeons. Similar to blastomycosis, the primary infection site most commonly is the lungs. It subsequently may disseminate to the skin or less commonly via direct inoculation of injured skin. It can present as papules, plaques, ulcers, purpura, or abscesses. Unlike blastomycosis, tissue biopsy of a cutaneous lesion reveals granuloma formation and distinctive oval, narrow-based budding yeast.⁵ Atypical mycobacteria are another source of infection to consider. For example, cutaneous Mycobacterium kansasii may present as papules and pustules forming verrucous or granulomatous plaques and ulceration. Histopathologic findings distinguishing mycobacterial infection from blastomycosis include granulomas and acid-fast bacilli in histiocytes.⁶

Noninfectious etiologies in the differential may include cutaneous squamous cell carcinoma or pemphigus vegetans. Squamous cell carcinoma may present with a broad range of clinical features—papules, plaques, or nodules with smooth, scaly, verrucous, or ulcerative secondary features all are possible presentations.⁷ Fairskinned individuals, such as our patient, would be at a higher risk in sun-damaged skin. Histologically, cutaneous squamous cell carcinoma is defined as an invasion of the dermis by neoplastic squamous epithelial cells in the form of cords, sheets, individual cells, nodules, or cystic structures.⁷ Pemphigus vegetans is the rarest variant of a group of autoimmune vesiculobullous diseases known as pemphigus. It can be differentiated from the most common variant—pemphigus vulgaris—by the presence of vegetative plaques in intertriginous areas. However, these verrucous vegetations can be misleading and make clinical diagnosis difficult. Histopathologic findings of hyperkeratosis, pseudoepitheliomatous hyperplasia, papillomatosis, and acantholysis with a suprabasal cleft would confirm the diagnosis.⁸

In summary, cutaneous blastomycosis classically presents as verrucous crusting plaques, as seen in our patient. It is important to conduct a thorough history for environmental exposures, but definitive diagnosis of cutaneous blastomycosis involves skin biopsy with fungal culture. Treatment depends on the severity of disease and organ involvement. Itraconazole would be appropriate for mild to moderate blastomycosis.

The Diagnosis: Borrelial Lymphocytoma (Lymphocytoma Cutis)

A punch biopsy revealed an atypical lobular lymphoid infiltrate within the dermis and subcutaneous tissue with a mixed composition of CD3⁺ T cells and CD20⁺ B cells (quiz image, bottom). Immunohistochemical studies revealed a normal CD4:CD8 ratio with preservation of CD5 and CD7. CD30 was largely negative. CD21 failed to detect follicular dendritic cell networks, and κ/λ light chain staining confirmed a preserved ratio of polytypic plasma cells. There was limited staining with B-cell lymphoma (Bcl-2 and Bcl-6). Polymerase chain reaction studies for both T- and B-cell receptors were negative (polyclonal).

Lyme disease is the most frequently reported vectorborne infectious disease in the United States, and borrelial lymphocytoma (BL) is a rare clinical sequela. Borrelial lymphocytoma is a variant of lymphocytoma cutis (also known as benign reactive lymphoid hyperplasia), which is an inflammatory lesion that can mimic malignant lymphoma clinically and histologically. Lymphocytoma cutis is considered the prototypical example of cutaneous B-cell pseudolymphoma.¹ Due to suspicion for lymphocytoma cutis based on the histologic findings and characteristic location of the lesions in our patient, Lyme serologies were ordered and were positive for IgM antibodies against p23, p39, and p41 antigens in high titers. Our patient was treated with doxycycline 100 mg twice daily for 3 weeks with complete resolution of the lesions at 3-month follow-up.

Clinically, BL appears as erythematous papules, plaques, or nodules commonly on the lobules of the ears (quiz image, top). Most cases of lymphocytoma cutis are idiopathic but may be triggered by identifiable associated etiologies including Borrelia burgdorferi, Leishmania donovani, molluscum contagiosum, herpes zoster virus, vaccinations, tattoos, insect bites, and drugs. The main differential diagnosis of lymphocytoma cutis is cutaneous B-cell lymphoma. Pseudolymphoma of the skin can mimic nearly all immunohistochemical staining patterns of true B-cell lymphomas.²

Primary cutaneous follicle center lymphoma frequently occurs on the head and neck. This true lymphoma of the skin can demonstrate prominent follicle centers with centrocytes and fragmented germinal centers (Figure 1) or show a diffuse pattern.³ Most cases show conspicuous Bcl-6 staining, and IgH gene rearrangements can detect a clonal B-cell population in more than 50% of cases.⁴

Diffuse large B-cell lymphoma can occur as a primary cutaneous malignancy or as a manifestation of systemic disease.4 When arising in the skin, lesions tend to affect the extremities, and the disease is classified as diffuse large B-cell lymphoma, leg type. Histologically, sheets of large atypical lymphocytes with numerous mitoses are seen (Figure 2). These cells stain positively with Bcl-2 and frequently demonstrate Bcl-6 and MUM-1, none of which were seen in our case.4 Lymphomatoid papulosis (LyP) tends to present with relapsing erythematous papules. Patients occasionally develop LyP in association with mycosis fungoides or other lymphomas. Both LyP and primary cutaneous anaplastic large cell lymphoma demonstrate conspicuous CD30+ large cells that can be multinucleated or resemble the Reed-Sternberg cells seen in Hodgkin lymphoma (Figure 3).4 Arthropod bite reactions are common but may be confused with lymphomas and pseudolymphomas. The perivascular lymphocytic infiltrate seen in arthropod bite reactions may be dense and usually is associated with numerous eosinophils (Figure 4). Occasional plasma cells also can be seen, and if the infiltrate closely adheres to vascular structures, a diagnosis of erythema chronicum migrans also can be considered. Patients with chronic lymphocytic leukemia/lymphoma may demonstrate exaggerated or persistent arthropod bite reactions, and atypical lymphocytes can be detected admixed with the otherwise reactive infiltrate.⁴

Borrelia burgdorferi is primarily endemic to North America and Europe. It is a spirochete bacterium spread by the Ixodes tick that was first recognized as the etiologic agent in 1975 in Old Lyme, Connecticut, where it received its name.⁵ Most reported cases of Lyme disease occur in the northeastern United States, which correlates with this case given our patient’s place of residence.⁶ Borrelial lymphocytoma cutis occurs in areas endemic for the Ixodes tick in Europe and North America.⁷ When describing the genotyping of Borrelia seen in BL, the strain B burgdorferi previously was grouped with Borrelia afzelii and Borrelia garinii.² In the contemporary literature, however, B burgdorferi is referred to as sensu stricto when specifically talking about the strain B burgdorferi, and the term sensu lato is used when referencing the combination of strains (B burgdorferi, B afzelii, B garinii).

A 2016 study by Maraspin et al⁸ comprising 144 patients diagnosed with BL showed that the lesions mainly were located on the breast (106 patients [73.6%]) and the earlobe (27 patients [18.8%]), with the remaining cases occurring elsewhere on the body (11 patients [7.6%]). The Borrelia strains isolated from the BL lesions included B afzelii, Borrelia bissettii, and B garinii, with B afzelii being the most commonly identified (84.6% [11/13]).⁸

Borrelial lymphocytoma usually is categorized as a form of early disseminated Lyme disease and is treated as such. The treatment of choice for early disseminated Lyme disease is doxycycline 100 mg twice daily for 14 to 21 days. Ceftriaxone and azithromycin are reasonable treatment options for patients who have tetracycline allergies or who are pregnant.⁹

In conclusion, the presentation of red papules or nodules on the ears should prompt clinical suspicion of Lyme disease, particularly in endemic areas. Differentiating pseudolymphomas from true lymphomas and other reactive conditions can be challenging.

The Diagnosis: Borrelial Lymphocytoma (Lymphocytoma Cutis)

A punch biopsy revealed an atypical lobular lymphoid infiltrate within the dermis and subcutaneous tissue with a mixed composition of CD3⁺ T cells and CD20⁺ B cells (quiz image, bottom). Immunohistochemical studies revealed a normal CD4:CD8 ratio with preservation of CD5 and CD7. CD30 was largely negative. CD21 failed to detect follicular dendritic cell networks, and κ/λ light chain staining confirmed a preserved ratio of polytypic plasma cells. There was limited staining with B-cell lymphoma (Bcl-2 and Bcl-6). Polymerase chain reaction studies for both T- and B-cell receptors were negative (polyclonal).

Lyme disease is the most frequently reported vectorborne infectious disease in the United States, and borrelial lymphocytoma (BL) is a rare clinical sequela. Borrelial lymphocytoma is a variant of lymphocytoma cutis (also known as benign reactive lymphoid hyperplasia), which is an inflammatory lesion that can mimic malignant lymphoma clinically and histologically. Lymphocytoma cutis is considered the prototypical example of cutaneous B-cell pseudolymphoma.¹ Due to suspicion for lymphocytoma cutis based on the histologic findings and characteristic location of the lesions in our patient, Lyme serologies were ordered and were positive for IgM antibodies against p23, p39, and p41 antigens in high titers. Our patient was treated with doxycycline 100 mg twice daily for 3 weeks with complete resolution of the lesions at 3-month follow-up.

Clinically, BL appears as erythematous papules, plaques, or nodules commonly on the lobules of the ears (quiz image, top). Most cases of lymphocytoma cutis are idiopathic but may be triggered by identifiable associated etiologies including Borrelia burgdorferi, Leishmania donovani, molluscum contagiosum, herpes zoster virus, vaccinations, tattoos, insect bites, and drugs. The main differential diagnosis of lymphocytoma cutis is cutaneous B-cell lymphoma. Pseudolymphoma of the skin can mimic nearly all immunohistochemical staining patterns of true B-cell lymphomas.²

Primary cutaneous follicle center lymphoma frequently occurs on the head and neck. This true lymphoma of the skin can demonstrate prominent follicle centers with centrocytes and fragmented germinal centers (Figure 1) or show a diffuse pattern.³ Most cases show conspicuous Bcl-6 staining, and IgH gene rearrangements can detect a clonal B-cell population in more than 50% of cases.⁴

Diffuse large B-cell lymphoma can occur as a primary cutaneous malignancy or as a manifestation of systemic disease.4 When arising in the skin, lesions tend to affect the extremities, and the disease is classified as diffuse large B-cell lymphoma, leg type. Histologically, sheets of large atypical lymphocytes with numerous mitoses are seen (Figure 2). These cells stain positively with Bcl-2 and frequently demonstrate Bcl-6 and MUM-1, none of which were seen in our case.4 Lymphomatoid papulosis (LyP) tends to present with relapsing erythematous papules. Patients occasionally develop LyP in association with mycosis fungoides or other lymphomas. Both LyP and primary cutaneous anaplastic large cell lymphoma demonstrate conspicuous CD30+ large cells that can be multinucleated or resemble the Reed-Sternberg cells seen in Hodgkin lymphoma (Figure 3).4 Arthropod bite reactions are common but may be confused with lymphomas and pseudolymphomas. The perivascular lymphocytic infiltrate seen in arthropod bite reactions may be dense and usually is associated with numerous eosinophils (Figure 4). Occasional plasma cells also can be seen, and if the infiltrate closely adheres to vascular structures, a diagnosis of erythema chronicum migrans also can be considered. Patients with chronic lymphocytic leukemia/lymphoma may demonstrate exaggerated or persistent arthropod bite reactions, and atypical lymphocytes can be detected admixed with the otherwise reactive infiltrate.⁴

Borrelia burgdorferi is primarily endemic to North America and Europe. It is a spirochete bacterium spread by the Ixodes tick that was first recognized as the etiologic agent in 1975 in Old Lyme, Connecticut, where it received its name.⁵ Most reported cases of Lyme disease occur in the northeastern United States, which correlates with this case given our patient’s place of residence.⁶ Borrelial lymphocytoma cutis occurs in areas endemic for the Ixodes tick in Europe and North America.⁷ When describing the genotyping of Borrelia seen in BL, the strain B burgdorferi previously was grouped with Borrelia afzelii and Borrelia garinii.² In the contemporary literature, however, B burgdorferi is referred to as sensu stricto when specifically talking about the strain B burgdorferi, and the term sensu lato is used when referencing the combination of strains (B burgdorferi, B afzelii, B garinii).

A 2016 study by Maraspin et al⁸ comprising 144 patients diagnosed with BL showed that the lesions mainly were located on the breast (106 patients [73.6%]) and the earlobe (27 patients [18.8%]), with the remaining cases occurring elsewhere on the body (11 patients [7.6%]). The Borrelia strains isolated from the BL lesions included B afzelii, Borrelia bissettii, and B garinii, with B afzelii being the most commonly identified (84.6% [11/13]).⁸

Borrelial lymphocytoma usually is categorized as a form of early disseminated Lyme disease and is treated as such. The treatment of choice for early disseminated Lyme disease is doxycycline 100 mg twice daily for 14 to 21 days. Ceftriaxone and azithromycin are reasonable treatment options for patients who have tetracycline allergies or who are pregnant.⁹

In conclusion, the presentation of red papules or nodules on the ears should prompt clinical suspicion of Lyme disease, particularly in endemic areas. Differentiating pseudolymphomas from true lymphomas and other reactive conditions can be challenging.

The Diagnosis: Borrelial Lymphocytoma (Lymphocytoma Cutis)

A punch biopsy revealed an atypical lobular lymphoid infiltrate within the dermis and subcutaneous tissue with a mixed composition of CD3⁺ T cells and CD20⁺ B cells (quiz image, bottom). Immunohistochemical studies revealed a normal CD4:CD8 ratio with preservation of CD5 and CD7. CD30 was largely negative. CD21 failed to detect follicular dendritic cell networks, and κ/λ light chain staining confirmed a preserved ratio of polytypic plasma cells. There was limited staining with B-cell lymphoma (Bcl-2 and Bcl-6). Polymerase chain reaction studies for both T- and B-cell receptors were negative (polyclonal).

Lyme disease is the most frequently reported vectorborne infectious disease in the United States, and borrelial lymphocytoma (BL) is a rare clinical sequela. Borrelial lymphocytoma is a variant of lymphocytoma cutis (also known as benign reactive lymphoid hyperplasia), which is an inflammatory lesion that can mimic malignant lymphoma clinically and histologically. Lymphocytoma cutis is considered the prototypical example of cutaneous B-cell pseudolymphoma.¹ Due to suspicion for lymphocytoma cutis based on the histologic findings and characteristic location of the lesions in our patient, Lyme serologies were ordered and were positive for IgM antibodies against p23, p39, and p41 antigens in high titers. Our patient was treated with doxycycline 100 mg twice daily for 3 weeks with complete resolution of the lesions at 3-month follow-up.

Clinically, BL appears as erythematous papules, plaques, or nodules commonly on the lobules of the ears (quiz image, top). Most cases of lymphocytoma cutis are idiopathic but may be triggered by identifiable associated etiologies including Borrelia burgdorferi, Leishmania donovani, molluscum contagiosum, herpes zoster virus, vaccinations, tattoos, insect bites, and drugs. The main differential diagnosis of lymphocytoma cutis is cutaneous B-cell lymphoma. Pseudolymphoma of the skin can mimic nearly all immunohistochemical staining patterns of true B-cell lymphomas.²

Primary cutaneous follicle center lymphoma frequently occurs on the head and neck. This true lymphoma of the skin can demonstrate prominent follicle centers with centrocytes and fragmented germinal centers (Figure 1) or show a diffuse pattern.³ Most cases show conspicuous Bcl-6 staining, and IgH gene rearrangements can detect a clonal B-cell population in more than 50% of cases.⁴

Diffuse large B-cell lymphoma can occur as a primary cutaneous malignancy or as a manifestation of systemic disease.4 When arising in the skin, lesions tend to affect the extremities, and the disease is classified as diffuse large B-cell lymphoma, leg type. Histologically, sheets of large atypical lymphocytes with numerous mitoses are seen (Figure 2). These cells stain positively with Bcl-2 and frequently demonstrate Bcl-6 and MUM-1, none of which were seen in our case.4 Lymphomatoid papulosis (LyP) tends to present with relapsing erythematous papules. Patients occasionally develop LyP in association with mycosis fungoides or other lymphomas. Both LyP and primary cutaneous anaplastic large cell lymphoma demonstrate conspicuous CD30+ large cells that can be multinucleated or resemble the Reed-Sternberg cells seen in Hodgkin lymphoma (Figure 3).4 Arthropod bite reactions are common but may be confused with lymphomas and pseudolymphomas. The perivascular lymphocytic infiltrate seen in arthropod bite reactions may be dense and usually is associated with numerous eosinophils (Figure 4). Occasional plasma cells also can be seen, and if the infiltrate closely adheres to vascular structures, a diagnosis of erythema chronicum migrans also can be considered. Patients with chronic lymphocytic leukemia/lymphoma may demonstrate exaggerated or persistent arthropod bite reactions, and atypical lymphocytes can be detected admixed with the otherwise reactive infiltrate.⁴

Borrelia burgdorferi is primarily endemic to North America and Europe. It is a spirochete bacterium spread by the Ixodes tick that was first recognized as the etiologic agent in 1975 in Old Lyme, Connecticut, where it received its name.⁵ Most reported cases of Lyme disease occur in the northeastern United States, which correlates with this case given our patient’s place of residence.⁶ Borrelial lymphocytoma cutis occurs in areas endemic for the Ixodes tick in Europe and North America.⁷ When describing the genotyping of Borrelia seen in BL, the strain B burgdorferi previously was grouped with Borrelia afzelii and Borrelia garinii.² In the contemporary literature, however, B burgdorferi is referred to as sensu stricto when specifically talking about the strain B burgdorferi, and the term sensu lato is used when referencing the combination of strains (B burgdorferi, B afzelii, B garinii).

A 2016 study by Maraspin et al⁸ comprising 144 patients diagnosed with BL showed that the lesions mainly were located on the breast (106 patients [73.6%]) and the earlobe (27 patients [18.8%]), with the remaining cases occurring elsewhere on the body (11 patients [7.6%]). The Borrelia strains isolated from the BL lesions included B afzelii, Borrelia bissettii, and B garinii, with B afzelii being the most commonly identified (84.6% [11/13]).⁸

Borrelial lymphocytoma usually is categorized as a form of early disseminated Lyme disease and is treated as such. The treatment of choice for early disseminated Lyme disease is doxycycline 100 mg twice daily for 14 to 21 days. Ceftriaxone and azithromycin are reasonable treatment options for patients who have tetracycline allergies or who are pregnant.⁹

In conclusion, the presentation of red papules or nodules on the ears should prompt clinical suspicion of Lyme disease, particularly in endemic areas. Differentiating pseudolymphomas from true lymphomas and other reactive conditions can be challenging.

To the Editor:

A 57-year-old woman presented to an outpatient clinic with severe pruritus and burning of the skin as well as subjective fevers and chills. She had been discharged from a psychiatric hospital for attempted suicide 1 day prior. There were no recent changes in the medication regimen, which consisted of linaclotide, fluoxetine, lorazepam, and gabapentin. While admitted, the patient was started on the atypical antipsychotic cariprazine. Within 24 hours of the first dose, she developed severe facial erythema that progressed to diffuse erythema over more than 60% of the body surface area. The attending psychiatrist promptly discontinued cariprazine. During the next 24 hours, there were no reports of fever, leukocytosis, or signs of systemic organ involvement. Given the patient’s mental and medical stability, she was discharged with instructions to follow up with the outpatient dermatology clinic.

At the current presentation, physical examination revealed innumerable 1- to 4-mm pustules coalescing to lakes of pus on an erythematous base over more than 60% of the body surface area (Figure 1). The mucous membranes were clear of lesions, the Nikolsky sign was negative, and the patient’s temperature was 99.6 °F in the office. Complete blood cell count and complete metabolic panel results were within reference range.

A 4-mm abdominal punch biopsy showed subcorneal neutrophilic pustules, papillary dermal edema, and superficial dermal lymphohistiocytic inflammation with numerous neutrophils, eosinophils, and extravasated red blood cells, consistent with acute generalized exanthematous pustulosis (AGEP)(Figure 2). The patient was started on wet wraps with triamcinolone cream 0.1%.

Two days later, physical examination revealed the erythema noted on initial examination had notably decreased, and the patient no longer reported burning or pruritus. One week after initial presentation to the clinic, the patient’s rash had resolved, and only a few small areas of desquamation remained.

Acute generalized exanthematous pustulosis is a severe cutaneous adverse reaction characterized by the development of numerous nonfollicular sterile pustules on an edematous and erythematous base. In almost 90% of reported cases, the cause is related to use of antibiotics, antifungals, antimalarials, or diltiazem (a calcium channel blocker). This rare cutaneous reaction occurs in 1 to 5 patients per million per year¹; it carries a 1% to 2% mortality rate with proper supportive treatment.

The clinical symptoms of AGEP typically present 24 to 48 hours after drug initiation with the rapid development of dozens to thousands of 1- to 4-mm pustules, typically localized to the flexor surfaces and face. In the setting of AGEP, acute onset of fever and leukocytosis typically occur at the time of the cutaneous eruption. These features were absent in this patient. The eruption usually starts on the face and then migrates to the trunk and extremities, sparing the palms and soles. Systemic involvement most commonly presents as hepatic, renal, or pulmonary insufficiency, which has been seen in 20% of cases.²

The immunologic response associated with the reaction has been studied in vitro. Drug-specific CD8 T cells use perforin/granzyme B and Fas ligand mechanisms to induce apoptosis of the keratinocytes within the epidermis, leading to vesicle formation.³ During the very first stages of formation, vesicles mainly comprise CD8 T cells and keratinocytes. These cells then begin producing CXC-18, a potent neutrophil chemokine, leading to extensive chemotaxis of neutrophils into vesicles, which then rapidly transform to pustules.³ This rapid transformation leads to the lakes of pustules, a description often associated with AGEP.

Treatment of AGEP is mainly supportive and consists of discontinuing use of the causative agent. Topical corticosteroids can be used during the pustular phase for symptom management. There is no evidence that systemic steroids reduce the duration of the disease.² Other supportive measures such as application of wet wraps can be used to provide comfort.

Cutaneous adverse drug reactions commonly are associated with psychiatric pharmacotherapy, but first-and second-generation antipsychotics rarely are associated with these types of reactions. In this patient, the causative agent of the AGEP was cariprazine, an atypical antipsychotic that had no reported association with AGEP or cutaneous adverse drug reactions prior to this presentation.

To the Editor:

A 57-year-old woman presented to an outpatient clinic with severe pruritus and burning of the skin as well as subjective fevers and chills. She had been discharged from a psychiatric hospital for attempted suicide 1 day prior. There were no recent changes in the medication regimen, which consisted of linaclotide, fluoxetine, lorazepam, and gabapentin. While admitted, the patient was started on the atypical antipsychotic cariprazine. Within 24 hours of the first dose, she developed severe facial erythema that progressed to diffuse erythema over more than 60% of the body surface area. The attending psychiatrist promptly discontinued cariprazine. During the next 24 hours, there were no reports of fever, leukocytosis, or signs of systemic organ involvement. Given the patient’s mental and medical stability, she was discharged with instructions to follow up with the outpatient dermatology clinic.

At the current presentation, physical examination revealed innumerable 1- to 4-mm pustules coalescing to lakes of pus on an erythematous base over more than 60% of the body surface area (Figure 1). The mucous membranes were clear of lesions, the Nikolsky sign was negative, and the patient’s temperature was 99.6 °F in the office. Complete blood cell count and complete metabolic panel results were within reference range.

A 4-mm abdominal punch biopsy showed subcorneal neutrophilic pustules, papillary dermal edema, and superficial dermal lymphohistiocytic inflammation with numerous neutrophils, eosinophils, and extravasated red blood cells, consistent with acute generalized exanthematous pustulosis (AGEP)(Figure 2). The patient was started on wet wraps with triamcinolone cream 0.1%.

Two days later, physical examination revealed the erythema noted on initial examination had notably decreased, and the patient no longer reported burning or pruritus. One week after initial presentation to the clinic, the patient’s rash had resolved, and only a few small areas of desquamation remained.

Acute generalized exanthematous pustulosis is a severe cutaneous adverse reaction characterized by the development of numerous nonfollicular sterile pustules on an edematous and erythematous base. In almost 90% of reported cases, the cause is related to use of antibiotics, antifungals, antimalarials, or diltiazem (a calcium channel blocker). This rare cutaneous reaction occurs in 1 to 5 patients per million per year¹; it carries a 1% to 2% mortality rate with proper supportive treatment.

The clinical symptoms of AGEP typically present 24 to 48 hours after drug initiation with the rapid development of dozens to thousands of 1- to 4-mm pustules, typically localized to the flexor surfaces and face. In the setting of AGEP, acute onset of fever and leukocytosis typically occur at the time of the cutaneous eruption. These features were absent in this patient. The eruption usually starts on the face and then migrates to the trunk and extremities, sparing the palms and soles. Systemic involvement most commonly presents as hepatic, renal, or pulmonary insufficiency, which has been seen in 20% of cases.²

The immunologic response associated with the reaction has been studied in vitro. Drug-specific CD8 T cells use perforin/granzyme B and Fas ligand mechanisms to induce apoptosis of the keratinocytes within the epidermis, leading to vesicle formation.³ During the very first stages of formation, vesicles mainly comprise CD8 T cells and keratinocytes. These cells then begin producing CXC-18, a potent neutrophil chemokine, leading to extensive chemotaxis of neutrophils into vesicles, which then rapidly transform to pustules.³ This rapid transformation leads to the lakes of pustules, a description often associated with AGEP.

Treatment of AGEP is mainly supportive and consists of discontinuing use of the causative agent. Topical corticosteroids can be used during the pustular phase for symptom management. There is no evidence that systemic steroids reduce the duration of the disease.² Other supportive measures such as application of wet wraps can be used to provide comfort.

Cutaneous adverse drug reactions commonly are associated with psychiatric pharmacotherapy, but first-and second-generation antipsychotics rarely are associated with these types of reactions. In this patient, the causative agent of the AGEP was cariprazine, an atypical antipsychotic that had no reported association with AGEP or cutaneous adverse drug reactions prior to this presentation.

To the Editor:

A 57-year-old woman presented to an outpatient clinic with severe pruritus and burning of the skin as well as subjective fevers and chills. She had been discharged from a psychiatric hospital for attempted suicide 1 day prior. There were no recent changes in the medication regimen, which consisted of linaclotide, fluoxetine, lorazepam, and gabapentin. While admitted, the patient was started on the atypical antipsychotic cariprazine. Within 24 hours of the first dose, she developed severe facial erythema that progressed to diffuse erythema over more than 60% of the body surface area. The attending psychiatrist promptly discontinued cariprazine. During the next 24 hours, there were no reports of fever, leukocytosis, or signs of systemic organ involvement. Given the patient’s mental and medical stability, she was discharged with instructions to follow up with the outpatient dermatology clinic.

At the current presentation, physical examination revealed innumerable 1- to 4-mm pustules coalescing to lakes of pus on an erythematous base over more than 60% of the body surface area (Figure 1). The mucous membranes were clear of lesions, the Nikolsky sign was negative, and the patient’s temperature was 99.6 °F in the office. Complete blood cell count and complete metabolic panel results were within reference range.

A 4-mm abdominal punch biopsy showed subcorneal neutrophilic pustules, papillary dermal edema, and superficial dermal lymphohistiocytic inflammation with numerous neutrophils, eosinophils, and extravasated red blood cells, consistent with acute generalized exanthematous pustulosis (AGEP)(Figure 2). The patient was started on wet wraps with triamcinolone cream 0.1%.

Two days later, physical examination revealed the erythema noted on initial examination had notably decreased, and the patient no longer reported burning or pruritus. One week after initial presentation to the clinic, the patient’s rash had resolved, and only a few small areas of desquamation remained.

Acute generalized exanthematous pustulosis is a severe cutaneous adverse reaction characterized by the development of numerous nonfollicular sterile pustules on an edematous and erythematous base. In almost 90% of reported cases, the cause is related to use of antibiotics, antifungals, antimalarials, or diltiazem (a calcium channel blocker). This rare cutaneous reaction occurs in 1 to 5 patients per million per year¹; it carries a 1% to 2% mortality rate with proper supportive treatment.

The clinical symptoms of AGEP typically present 24 to 48 hours after drug initiation with the rapid development of dozens to thousands of 1- to 4-mm pustules, typically localized to the flexor surfaces and face. In the setting of AGEP, acute onset of fever and leukocytosis typically occur at the time of the cutaneous eruption. These features were absent in this patient. The eruption usually starts on the face and then migrates to the trunk and extremities, sparing the palms and soles. Systemic involvement most commonly presents as hepatic, renal, or pulmonary insufficiency, which has been seen in 20% of cases.²

The immunologic response associated with the reaction has been studied in vitro. Drug-specific CD8 T cells use perforin/granzyme B and Fas ligand mechanisms to induce apoptosis of the keratinocytes within the epidermis, leading to vesicle formation.³ During the very first stages of formation, vesicles mainly comprise CD8 T cells and keratinocytes. These cells then begin producing CXC-18, a potent neutrophil chemokine, leading to extensive chemotaxis of neutrophils into vesicles, which then rapidly transform to pustules.³ This rapid transformation leads to the lakes of pustules, a description often associated with AGEP.

Treatment of AGEP is mainly supportive and consists of discontinuing use of the causative agent. Topical corticosteroids can be used during the pustular phase for symptom management. There is no evidence that systemic steroids reduce the duration of the disease.² Other supportive measures such as application of wet wraps can be used to provide comfort.

Cutaneous adverse drug reactions commonly are associated with psychiatric pharmacotherapy, but first-and second-generation antipsychotics rarely are associated with these types of reactions. In this patient, the causative agent of the AGEP was cariprazine, an atypical antipsychotic that had no reported association with AGEP or cutaneous adverse drug reactions prior to this presentation.

The Diagnosis: Tinea Corporis Bullosa

At the time of presentation, a potassium hydroxide (KOH) preparation, fungal culture, and punch biopsy of the right ventral wrist was performed. The KOH preparation was positive for fungal hyphae characteristic of dermatophyte infections. Histologically, the biopsy showed intraepidermal and subepidermal blisters with neutrophil- and lymphocyte-rich contents (Figure 1). Fungal hyphae and spores were present within the stratum corneum and superficial epidermis (Figure 2), and fungal cultures grew Microsporum canis. The extent of the rash (upper and lower extremities, chest, and back), positive fungal culture, and KOH preparation all supported the diagnosis of tinea corporis bullosa, which was confirmed with biopsy. Oral prednisone use was discouraged and triamcinolone ointment was discontinued given that inappropriate treatment with steroids in the setting of fungal infection suppresses an inflammatory response and alters clinical appearance, obviating the persistent underlying infection.

Tinea corporis bullosa is a rare superficial dermatophyte fungal infection that often is acquired by close personto- person contact or contact with domestic animals. The infection begins as a circular pruritic plaque, generally with raised borders, which may be erythematous or hyperpigmented. By definition, tinea corporis occurs in sites other than the face, feet, hands, or groin area. Bullae formation is thought to be secondary to a delayed hypersensitivity reaction provoked by the presence of a dermatophyte antigen.¹

Linear IgA bullous dermatosis is an immunemediated disease characterized by IgA deposition at the dermoepidermal junction. Linear IgA bullous dermatosis classically presents as widespread tense vesicles in an arciform or annular pattern. Mucosal involvement is common and typically presents with erosions, ulcerations, and scarring.² Given the absence of mucosal involvement in our patient and a positive KOH preparation, linear IgA bullous dermatosis was an unlikely diagnosis.

Benign inoculation lymphoreticulosis, more commonly known as cat scratch disease (CSD), is a Bartonella henselae infection that results from a cat scratch or bite. Cat scratch disease can present as localized cutaneous and nodal involvement (lymphadenopathy) near the site of inoculation, or it may present as disseminated disease. Cutaneous lesions generally progress through vesicular, erythematous, and papular phases. Regional lymphadenopathy proximal to the inoculation site is the hallmark of CSD.³ Given the absence of lymphadenopathy in our patient as well as the sporadic distribution of lesions, CSD was an unlikely diagnosis.

Dermatitis herpetiformis (DH) is an autoimmune disorder with cutaneous manifestations of gluten sensitivity. Dermatitis herpetiformis presents as extremely pruritic papules and vesicles arranged in groups on areas such as the elbows, dorsal aspects of the forearms, knees, scalp, back, and buttocks. Most patients with DH have celiac disease or small bowel disease related to gluten sensitivity.4 Given our patient’s acute presentation in adulthood and lack of gluten sensitivity, DH was an unlikely diagnosis.

Bullous fixed drug reaction is a cutaneous eruption that typically presents in the setting of exposure to an offending drug/agent. Drug reactions can have various cutaneous presentations, with the most common being pigmented macules that progress into plaques.⁵ Given the isolated nature of our patient’s episode and apparent lack of association with medication, bullous fixed drug reaction was an unlikely diagnosis.

Tinea corporis bullosa is a rare clinical variant of tinea corporis that has only been reported in patients with a history of contact with different animals. There are many causative organisms related to tinea corporis; Trichophyton rubrum is the most common etiology of tinea corporis, while tinea corporis due to close contact with domesticated animals often is caused by M canis.⁶ The immunoinhibitory properties of the mannans in the fungal cell wall allow the organisms to adhere to the skin prior to invasion. Cutaneous invasion into dead cornified layers of the skin is credited to the proteases, subtilisinlike proteases (subtilases), and keratinases produced by the fungus.¹ There are many different clinical presentations of tinea corporis due to the variability of causative organisms. An annular (ring-shaped) lesion with a central plaque and advancing border is the most typical presentation. Tinea corporis bullosa is characterized by the presence of bullae or vesicles in the borders of the scaly plaque. Rupture of the bullae subsequently leads to erosions and crusts over the plaque.

The diagnosis of tinea corporis bullosa often is clinical if the lesion is typical and can be confirmed using KOH preparation and fungal culture. Once the diagnosis is confirmed, topical antifungals are the standard treatment approach for localized superficial tinea corporis. Systemic antifungal treatment can be initiated if the lesion is extensive, recurrent, chronic, or unresponsive to topical treatment.¹ Given our patient’s characteristic presentation, she was managed with an over-the-counter topical antifungal (terbinafine). The patient’s lesions dramatically improved, rendering oral therapy unnecessary. At 1-month follow-up, the rash had nearly resolved.

The Diagnosis: Tinea Corporis Bullosa

At the time of presentation, a potassium hydroxide (KOH) preparation, fungal culture, and punch biopsy of the right ventral wrist was performed. The KOH preparation was positive for fungal hyphae characteristic of dermatophyte infections. Histologically, the biopsy showed intraepidermal and subepidermal blisters with neutrophil- and lymphocyte-rich contents (Figure 1). Fungal hyphae and spores were present within the stratum corneum and superficial epidermis (Figure 2), and fungal cultures grew Microsporum canis. The extent of the rash (upper and lower extremities, chest, and back), positive fungal culture, and KOH preparation all supported the diagnosis of tinea corporis bullosa, which was confirmed with biopsy. Oral prednisone use was discouraged and triamcinolone ointment was discontinued given that inappropriate treatment with steroids in the setting of fungal infection suppresses an inflammatory response and alters clinical appearance, obviating the persistent underlying infection.

Tinea corporis bullosa is a rare superficial dermatophyte fungal infection that often is acquired by close personto- person contact or contact with domestic animals. The infection begins as a circular pruritic plaque, generally with raised borders, which may be erythematous or hyperpigmented. By definition, tinea corporis occurs in sites other than the face, feet, hands, or groin area. Bullae formation is thought to be secondary to a delayed hypersensitivity reaction provoked by the presence of a dermatophyte antigen.¹

Linear IgA bullous dermatosis is an immunemediated disease characterized by IgA deposition at the dermoepidermal junction. Linear IgA bullous dermatosis classically presents as widespread tense vesicles in an arciform or annular pattern. Mucosal involvement is common and typically presents with erosions, ulcerations, and scarring.² Given the absence of mucosal involvement in our patient and a positive KOH preparation, linear IgA bullous dermatosis was an unlikely diagnosis.

Benign inoculation lymphoreticulosis, more commonly known as cat scratch disease (CSD), is a Bartonella henselae infection that results from a cat scratch or bite. Cat scratch disease can present as localized cutaneous and nodal involvement (lymphadenopathy) near the site of inoculation, or it may present as disseminated disease. Cutaneous lesions generally progress through vesicular, erythematous, and papular phases. Regional lymphadenopathy proximal to the inoculation site is the hallmark of CSD.³ Given the absence of lymphadenopathy in our patient as well as the sporadic distribution of lesions, CSD was an unlikely diagnosis.

Dermatitis herpetiformis (DH) is an autoimmune disorder with cutaneous manifestations of gluten sensitivity. Dermatitis herpetiformis presents as extremely pruritic papules and vesicles arranged in groups on areas such as the elbows, dorsal aspects of the forearms, knees, scalp, back, and buttocks. Most patients with DH have celiac disease or small bowel disease related to gluten sensitivity.4 Given our patient’s acute presentation in adulthood and lack of gluten sensitivity, DH was an unlikely diagnosis.

Bullous fixed drug reaction is a cutaneous eruption that typically presents in the setting of exposure to an offending drug/agent. Drug reactions can have various cutaneous presentations, with the most common being pigmented macules that progress into plaques.⁵ Given the isolated nature of our patient’s episode and apparent lack of association with medication, bullous fixed drug reaction was an unlikely diagnosis.

Tinea corporis bullosa is a rare clinical variant of tinea corporis that has only been reported in patients with a history of contact with different animals. There are many causative organisms related to tinea corporis; Trichophyton rubrum is the most common etiology of tinea corporis, while tinea corporis due to close contact with domesticated animals often is caused by M canis.⁶ The immunoinhibitory properties of the mannans in the fungal cell wall allow the organisms to adhere to the skin prior to invasion. Cutaneous invasion into dead cornified layers of the skin is credited to the proteases, subtilisinlike proteases (subtilases), and keratinases produced by the fungus.¹ There are many different clinical presentations of tinea corporis due to the variability of causative organisms. An annular (ring-shaped) lesion with a central plaque and advancing border is the most typical presentation. Tinea corporis bullosa is characterized by the presence of bullae or vesicles in the borders of the scaly plaque. Rupture of the bullae subsequently leads to erosions and crusts over the plaque.

The diagnosis of tinea corporis bullosa often is clinical if the lesion is typical and can be confirmed using KOH preparation and fungal culture. Once the diagnosis is confirmed, topical antifungals are the standard treatment approach for localized superficial tinea corporis. Systemic antifungal treatment can be initiated if the lesion is extensive, recurrent, chronic, or unresponsive to topical treatment.¹ Given our patient’s characteristic presentation, she was managed with an over-the-counter topical antifungal (terbinafine). The patient’s lesions dramatically improved, rendering oral therapy unnecessary. At 1-month follow-up, the rash had nearly resolved.

The Diagnosis: Tinea Corporis Bullosa

At the time of presentation, a potassium hydroxide (KOH) preparation, fungal culture, and punch biopsy of the right ventral wrist was performed. The KOH preparation was positive for fungal hyphae characteristic of dermatophyte infections. Histologically, the biopsy showed intraepidermal and subepidermal blisters with neutrophil- and lymphocyte-rich contents (Figure 1). Fungal hyphae and spores were present within the stratum corneum and superficial epidermis (Figure 2), and fungal cultures grew Microsporum canis. The extent of the rash (upper and lower extremities, chest, and back), positive fungal culture, and KOH preparation all supported the diagnosis of tinea corporis bullosa, which was confirmed with biopsy. Oral prednisone use was discouraged and triamcinolone ointment was discontinued given that inappropriate treatment with steroids in the setting of fungal infection suppresses an inflammatory response and alters clinical appearance, obviating the persistent underlying infection.

Tinea corporis bullosa is a rare superficial dermatophyte fungal infection that often is acquired by close personto- person contact or contact with domestic animals. The infection begins as a circular pruritic plaque, generally with raised borders, which may be erythematous or hyperpigmented. By definition, tinea corporis occurs in sites other than the face, feet, hands, or groin area. Bullae formation is thought to be secondary to a delayed hypersensitivity reaction provoked by the presence of a dermatophyte antigen.¹

Linear IgA bullous dermatosis is an immunemediated disease characterized by IgA deposition at the dermoepidermal junction. Linear IgA bullous dermatosis classically presents as widespread tense vesicles in an arciform or annular pattern. Mucosal involvement is common and typically presents with erosions, ulcerations, and scarring.² Given the absence of mucosal involvement in our patient and a positive KOH preparation, linear IgA bullous dermatosis was an unlikely diagnosis.

Benign inoculation lymphoreticulosis, more commonly known as cat scratch disease (CSD), is a Bartonella henselae infection that results from a cat scratch or bite. Cat scratch disease can present as localized cutaneous and nodal involvement (lymphadenopathy) near the site of inoculation, or it may present as disseminated disease. Cutaneous lesions generally progress through vesicular, erythematous, and papular phases. Regional lymphadenopathy proximal to the inoculation site is the hallmark of CSD.³ Given the absence of lymphadenopathy in our patient as well as the sporadic distribution of lesions, CSD was an unlikely diagnosis.

Dermatitis herpetiformis (DH) is an autoimmune disorder with cutaneous manifestations of gluten sensitivity. Dermatitis herpetiformis presents as extremely pruritic papules and vesicles arranged in groups on areas such as the elbows, dorsal aspects of the forearms, knees, scalp, back, and buttocks. Most patients with DH have celiac disease or small bowel disease related to gluten sensitivity.4 Given our patient’s acute presentation in adulthood and lack of gluten sensitivity, DH was an unlikely diagnosis.

Bullous fixed drug reaction is a cutaneous eruption that typically presents in the setting of exposure to an offending drug/agent. Drug reactions can have various cutaneous presentations, with the most common being pigmented macules that progress into plaques.⁵ Given the isolated nature of our patient’s episode and apparent lack of association with medication, bullous fixed drug reaction was an unlikely diagnosis.

Tinea corporis bullosa is a rare clinical variant of tinea corporis that has only been reported in patients with a history of contact with different animals. There are many causative organisms related to tinea corporis; Trichophyton rubrum is the most common etiology of tinea corporis, while tinea corporis due to close contact with domesticated animals often is caused by M canis.⁶ The immunoinhibitory properties of the mannans in the fungal cell wall allow the organisms to adhere to the skin prior to invasion. Cutaneous invasion into dead cornified layers of the skin is credited to the proteases, subtilisinlike proteases (subtilases), and keratinases produced by the fungus.¹ There are many different clinical presentations of tinea corporis due to the variability of causative organisms. An annular (ring-shaped) lesion with a central plaque and advancing border is the most typical presentation. Tinea corporis bullosa is characterized by the presence of bullae or vesicles in the borders of the scaly plaque. Rupture of the bullae subsequently leads to erosions and crusts over the plaque.

The diagnosis of tinea corporis bullosa often is clinical if the lesion is typical and can be confirmed using KOH preparation and fungal culture. Once the diagnosis is confirmed, topical antifungals are the standard treatment approach for localized superficial tinea corporis. Systemic antifungal treatment can be initiated if the lesion is extensive, recurrent, chronic, or unresponsive to topical treatment.¹ Given our patient’s characteristic presentation, she was managed with an over-the-counter topical antifungal (terbinafine). The patient’s lesions dramatically improved, rendering oral therapy unnecessary. At 1-month follow-up, the rash had nearly resolved.

The Diagnosis: Lymphomatoid Papulosis

At the time of the initial visit, a punch biopsy was performed on the posterior shoulder girdle. Histopathology revealed mild epidermal spongiosis and acanthosis with associated parakeratosis and a dermal lymphocytic infiltrate with extravasated erythrocytes consistent with pityriasis rosea (Figure 1). Two weeks after the biopsy, the patient returned for suture removal and to discuss the biopsy results. The patient reported more evolving lesions despite completing the prescribed course of dicloxacillin. At this time, physical examination revealed the persistence of several reddishbrown papules along with new nodular lesions on the arms and thighs, some with central ulceration and crusting (Figure 2). A second biopsy of a nodular lesion on the right distal forearm was performed at this visit along with a superficial tissue culture, which was negative for bacterial or fungal elements. The biopsy revealed an atypical CD30⁺ lymphoid proliferation (Figure 3). These cells were strongly PD-L1 positive and also positive for CD3, CD4, and granzyme-B. Ki67 showed a high proliferation rate, and T-cell gene rearrangement studies were positive. Given these histologic findings and the clinical context of rapidly evolving skin lesions from small papules to nodular skin tumors, a diagnosis of lymphomatoid papulosis (LyP) was established.

Because of the notable pathologic discordance between the 2 biopsy specimens, re-evaluation of the initial specimen was requested. The initial biopsy was subsequently found to be CD30⁺ with an identical peak on gene rearrangement studies as the second biopsy, further validating the diagnosis of LyP (Figure 4). Our patient was offered low-dose methotrexate therapy but declined the treatment plan, as the skin lesions had begun to resolve.

Lymphomatoid papulosis is a chronic CD30⁺ lymphoproliferative disorder with a characteristic recurrent and self-remitting disease course.^1,2 Although it typically has a benign clinical course, it is histologically malignant and considered a low-grade variant of cutaneous T-cell lymphoma. ^2,3 The classic clinical presentation of LyP involves the presence of reddish-brown papules and nodules typically measuring less than 2.0 cm, which may show evidence of central ulceration, hemorrhage, necrosis, and/or crust formation.^1-5 It is characteristic that a patient may present with these skin lesions in different stages of evolution and that biopsies of these lesions may reflect different histologic features depending on the age of the lesion, making a definitive diagnosis more difficult to obtain if not clinically correlated.^1,2 Any part of the body may be involved; however, there appears to be a predilection for the trunk and extremities in most cases.^1-3,5 The skin eruptions usually are asymptomatic, but pruritus is a commonly associated concern.^1,2,4,5

Lymphomatoid papulosis can have a localized, clustered, or generalized distribution pattern and typically will spontaneously regress without treatment within 3 to 12 weeks of symptom onset.^2,3 Lymphomatoid papulosis has a slight male predominance with a male to female ratio of 1.5:1. It occurs most commonly between 35 and 45 years of age, though it can present at any age. The overall duration of the disease can range from months to decades.^2,3 Lymphomatoid papulosis makes up approximately 15% of all cutaneous T-cell lymphomas.^2,3 Although the overall prognosis is excellent, patients with LyP are at an increased risk of developing cutaneous or systemic lymphoma, most commonly mycosis fungoides, anaplastic large cell lymphoma, or Hodgkin lymphoma.^1-3 This increased lifelong risk is the reason that patients with LyP must be followed long-term every 6 to 12 months for surveillance of emerging malignancy.^1,2,6

The pathogenesis of LyP remains unknown. Some have hypothesized a possible viral trigger; however, there is insufficient data to support this theory.^2,6 A diagnostic hallmark of LyP is its CD30 positivity, which is a known marker for T-cell activation.6 The spontaneous regression of skin lesions that is characteristic of LyP is believed to involve the interactions between CD30 and its ligand (CD30L), which may contribute to apoptosis of neoplastic T cells.^2,3,6 With regards to the possible mechanisms contributing to tumor progression in LyP, a mutation in the transforming growth factor β receptor gene on CD30+ tumor cells within LyP lesions may allow for these cells to evade growth regulation and progress to lymphoma.^2,6 A large percentage of LyP biopsy specimens show evidence of T-cell receptor gene monoclonal rearrangement, which can aid in establishing a diagnosis.^1,2

The histologic features of LyP can vary greatly depending on the age of the lesion sampled.^1,2 Histologic subtypes of LyP have been established, with type A being the most common (approximately 75% of cases), displaying a wedge-shaped infiltrate of scattered or clustered, large, atypical CD30+ T cells.^1,2 Types B through E vary in histologic features, with the exception that all subtypes contain a CD30+ lymphocytic infiltrate.^2,3

Treatment of LyP depends on the symptom/disease burden that the patient is experiencing. For patients with a limited number of nonscarring skin lesions in areas that are not cosmetically sensitive, observation is recommended. ^1-3 For symptomatic patients with an extensive number of lesions, particularly those that may be scarring and/or in cosmetically sensitive areas, low-dose oral methotrexate therapy is considered first-line treatment.^1-4 A methotrexate dose of 5 to 20 mg weekly can be effective in reducing the number and severity of lesions, with duration of treatment depending on clinical response.^1,2 For patients who have contraindications to or who cannot tolerate oral methotrexate, phototherapy using psoralen plus UVA twice weekly for 6 to 8 weeks is another treatment option.^1,2 Topical corticosteroids also can be used in children or for patients experiencing substantial pruritus.^1,2,4 Oral or topical retinoids, topical carmustine or mechlorethamine, and brentuximab (an anti-CD30 monoclonal antibody) are all alternative therapies that have shown some beneficial effects.^1,2 In the event that any of the skin lesions do not spontaneously regress within a 3- to 12-week time frame, surgical excision or radiotherapy can be performed on those lesions.²

Primary cutaneous anaplastic large cell lymphoma (C-ALCL) is another CD30+ lymphoproliferative disorder with overlapping clinical and histopathological features of LyP. Recurrent crops of multiple lesions favor a diagnosis of LyP, whereas solitary lesions favor C-ALCL; however, multifocal C-ALCL cases may occur.² Mycosis fungoides is the most common type of cutaneous T-cell lymphoma that characteristically presents in a patch, plaque, tumor progression. Although mycosis fungoides eventually may transform into a CD30⁺ lymphoma, our patient did not display the characteristic clinical progression to suggest this diagnosis. Pityriasis lichenoides et varioliformis acuta and pityriasis lichenoides chronica also fall into the spectrum of clonal T-cell cutaneous disorders that more commonly affect the pediatric population. Pityriasis lichenoides et varioliformis acuta has a marked CD8⁺ lymphocyte infiltrate, whereas pityriasis lichenoides chronica has more CD4⁺ lymphocytes. These disorders typically do not stain positive for CD30.²

All patients with a diagnosis of LyP should maintain lifelong, regular, 6- to 12-month follow-up visits to monitor disease status and screen for any evidence of developing malignancy.^1,2,6 A thorough review of clinical history, complete skin examination, and physical examination with a particular focus on detection of lymphadenopathy and hepatosplenomegaly should be included at every followup visit.1 Systemic symptoms such as fever, night sweats, or weight loss are not typical features of LyP; therefore, patients who begin to develop these symptoms should be promptly evaluated for systemic lymphoma.¹

The Diagnosis: Lymphomatoid Papulosis

At the time of the initial visit, a punch biopsy was performed on the posterior shoulder girdle. Histopathology revealed mild epidermal spongiosis and acanthosis with associated parakeratosis and a dermal lymphocytic infiltrate with extravasated erythrocytes consistent with pityriasis rosea (Figure 1). Two weeks after the biopsy, the patient returned for suture removal and to discuss the biopsy results. The patient reported more evolving lesions despite completing the prescribed course of dicloxacillin. At this time, physical examination revealed the persistence of several reddishbrown papules along with new nodular lesions on the arms and thighs, some with central ulceration and crusting (Figure 2). A second biopsy of a nodular lesion on the right distal forearm was performed at this visit along with a superficial tissue culture, which was negative for bacterial or fungal elements. The biopsy revealed an atypical CD30⁺ lymphoid proliferation (Figure 3). These cells were strongly PD-L1 positive and also positive for CD3, CD4, and granzyme-B. Ki67 showed a high proliferation rate, and T-cell gene rearrangement studies were positive. Given these histologic findings and the clinical context of rapidly evolving skin lesions from small papules to nodular skin tumors, a diagnosis of lymphomatoid papulosis (LyP) was established.

Because of the notable pathologic discordance between the 2 biopsy specimens, re-evaluation of the initial specimen was requested. The initial biopsy was subsequently found to be CD30⁺ with an identical peak on gene rearrangement studies as the second biopsy, further validating the diagnosis of LyP (Figure 4). Our patient was offered low-dose methotrexate therapy but declined the treatment plan, as the skin lesions had begun to resolve.

Lymphomatoid papulosis is a chronic CD30⁺ lymphoproliferative disorder with a characteristic recurrent and self-remitting disease course.^1,2 Although it typically has a benign clinical course, it is histologically malignant and considered a low-grade variant of cutaneous T-cell lymphoma. ^2,3 The classic clinical presentation of LyP involves the presence of reddish-brown papules and nodules typically measuring less than 2.0 cm, which may show evidence of central ulceration, hemorrhage, necrosis, and/or crust formation.^1-5 It is characteristic that a patient may present with these skin lesions in different stages of evolution and that biopsies of these lesions may reflect different histologic features depending on the age of the lesion, making a definitive diagnosis more difficult to obtain if not clinically correlated.^1,2 Any part of the body may be involved; however, there appears to be a predilection for the trunk and extremities in most cases.^1-3,5 The skin eruptions usually are asymptomatic, but pruritus is a commonly associated concern.^1,2,4,5

Lymphomatoid papulosis can have a localized, clustered, or generalized distribution pattern and typically will spontaneously regress without treatment within 3 to 12 weeks of symptom onset.^2,3 Lymphomatoid papulosis has a slight male predominance with a male to female ratio of 1.5:1. It occurs most commonly between 35 and 45 years of age, though it can present at any age. The overall duration of the disease can range from months to decades.^2,3 Lymphomatoid papulosis makes up approximately 15% of all cutaneous T-cell lymphomas.^2,3 Although the overall prognosis is excellent, patients with LyP are at an increased risk of developing cutaneous or systemic lymphoma, most commonly mycosis fungoides, anaplastic large cell lymphoma, or Hodgkin lymphoma.^1-3 This increased lifelong risk is the reason that patients with LyP must be followed long-term every 6 to 12 months for surveillance of emerging malignancy.^1,2,6

The pathogenesis of LyP remains unknown. Some have hypothesized a possible viral trigger; however, there is insufficient data to support this theory.^2,6 A diagnostic hallmark of LyP is its CD30 positivity, which is a known marker for T-cell activation.6 The spontaneous regression of skin lesions that is characteristic of LyP is believed to involve the interactions between CD30 and its ligand (CD30L), which may contribute to apoptosis of neoplastic T cells.^2,3,6 With regards to the possible mechanisms contributing to tumor progression in LyP, a mutation in the transforming growth factor β receptor gene on CD30+ tumor cells within LyP lesions may allow for these cells to evade growth regulation and progress to lymphoma.^2,6 A large percentage of LyP biopsy specimens show evidence of T-cell receptor gene monoclonal rearrangement, which can aid in establishing a diagnosis.^1,2

The histologic features of LyP can vary greatly depending on the age of the lesion sampled.^1,2 Histologic subtypes of LyP have been established, with type A being the most common (approximately 75% of cases), displaying a wedge-shaped infiltrate of scattered or clustered, large, atypical CD30+ T cells.^1,2 Types B through E vary in histologic features, with the exception that all subtypes contain a CD30+ lymphocytic infiltrate.^2,3

Treatment of LyP depends on the symptom/disease burden that the patient is experiencing. For patients with a limited number of nonscarring skin lesions in areas that are not cosmetically sensitive, observation is recommended. ^1-3 For symptomatic patients with an extensive number of lesions, particularly those that may be scarring and/or in cosmetically sensitive areas, low-dose oral methotrexate therapy is considered first-line treatment.^1-4 A methotrexate dose of 5 to 20 mg weekly can be effective in reducing the number and severity of lesions, with duration of treatment depending on clinical response.^1,2 For patients who have contraindications to or who cannot tolerate oral methotrexate, phototherapy using psoralen plus UVA twice weekly for 6 to 8 weeks is another treatment option.^1,2 Topical corticosteroids also can be used in children or for patients experiencing substantial pruritus.^1,2,4 Oral or topical retinoids, topical carmustine or mechlorethamine, and brentuximab (an anti-CD30 monoclonal antibody) are all alternative therapies that have shown some beneficial effects.^1,2 In the event that any of the skin lesions do not spontaneously regress within a 3- to 12-week time frame, surgical excision or radiotherapy can be performed on those lesions.²

Primary cutaneous anaplastic large cell lymphoma (C-ALCL) is another CD30+ lymphoproliferative disorder with overlapping clinical and histopathological features of LyP. Recurrent crops of multiple lesions favor a diagnosis of LyP, whereas solitary lesions favor C-ALCL; however, multifocal C-ALCL cases may occur.² Mycosis fungoides is the most common type of cutaneous T-cell lymphoma that characteristically presents in a patch, plaque, tumor progression. Although mycosis fungoides eventually may transform into a CD30⁺ lymphoma, our patient did not display the characteristic clinical progression to suggest this diagnosis. Pityriasis lichenoides et varioliformis acuta and pityriasis lichenoides chronica also fall into the spectrum of clonal T-cell cutaneous disorders that more commonly affect the pediatric population. Pityriasis lichenoides et varioliformis acuta has a marked CD8⁺ lymphocyte infiltrate, whereas pityriasis lichenoides chronica has more CD4⁺ lymphocytes. These disorders typically do not stain positive for CD30.²

All patients with a diagnosis of LyP should maintain lifelong, regular, 6- to 12-month follow-up visits to monitor disease status and screen for any evidence of developing malignancy.^1,2,6 A thorough review of clinical history, complete skin examination, and physical examination with a particular focus on detection of lymphadenopathy and hepatosplenomegaly should be included at every followup visit.1 Systemic symptoms such as fever, night sweats, or weight loss are not typical features of LyP; therefore, patients who begin to develop these symptoms should be promptly evaluated for systemic lymphoma.¹

The Diagnosis: Lymphomatoid Papulosis

At the time of the initial visit, a punch biopsy was performed on the posterior shoulder girdle. Histopathology revealed mild epidermal spongiosis and acanthosis with associated parakeratosis and a dermal lymphocytic infiltrate with extravasated erythrocytes consistent with pityriasis rosea (Figure 1). Two weeks after the biopsy, the patient returned for suture removal and to discuss the biopsy results. The patient reported more evolving lesions despite completing the prescribed course of dicloxacillin. At this time, physical examination revealed the persistence of several reddishbrown papules along with new nodular lesions on the arms and thighs, some with central ulceration and crusting (Figure 2). A second biopsy of a nodular lesion on the right distal forearm was performed at this visit along with a superficial tissue culture, which was negative for bacterial or fungal elements. The biopsy revealed an atypical CD30⁺ lymphoid proliferation (Figure 3). These cells were strongly PD-L1 positive and also positive for CD3, CD4, and granzyme-B. Ki67 showed a high proliferation rate, and T-cell gene rearrangement studies were positive. Given these histologic findings and the clinical context of rapidly evolving skin lesions from small papules to nodular skin tumors, a diagnosis of lymphomatoid papulosis (LyP) was established.

Because of the notable pathologic discordance between the 2 biopsy specimens, re-evaluation of the initial specimen was requested. The initial biopsy was subsequently found to be CD30⁺ with an identical peak on gene rearrangement studies as the second biopsy, further validating the diagnosis of LyP (Figure 4). Our patient was offered low-dose methotrexate therapy but declined the treatment plan, as the skin lesions had begun to resolve.

Lymphomatoid papulosis is a chronic CD30⁺ lymphoproliferative disorder with a characteristic recurrent and self-remitting disease course.^1,2 Although it typically has a benign clinical course, it is histologically malignant and considered a low-grade variant of cutaneous T-cell lymphoma. ^2,3 The classic clinical presentation of LyP involves the presence of reddish-brown papules and nodules typically measuring less than 2.0 cm, which may show evidence of central ulceration, hemorrhage, necrosis, and/or crust formation.^1-5 It is characteristic that a patient may present with these skin lesions in different stages of evolution and that biopsies of these lesions may reflect different histologic features depending on the age of the lesion, making a definitive diagnosis more difficult to obtain if not clinically correlated.^1,2 Any part of the body may be involved; however, there appears to be a predilection for the trunk and extremities in most cases.^1-3,5 The skin eruptions usually are asymptomatic, but pruritus is a commonly associated concern.^1,2,4,5

Lymphomatoid papulosis can have a localized, clustered, or generalized distribution pattern and typically will spontaneously regress without treatment within 3 to 12 weeks of symptom onset.^2,3 Lymphomatoid papulosis has a slight male predominance with a male to female ratio of 1.5:1. It occurs most commonly between 35 and 45 years of age, though it can present at any age. The overall duration of the disease can range from months to decades.^2,3 Lymphomatoid papulosis makes up approximately 15% of all cutaneous T-cell lymphomas.^2,3 Although the overall prognosis is excellent, patients with LyP are at an increased risk of developing cutaneous or systemic lymphoma, most commonly mycosis fungoides, anaplastic large cell lymphoma, or Hodgkin lymphoma.^1-3 This increased lifelong risk is the reason that patients with LyP must be followed long-term every 6 to 12 months for surveillance of emerging malignancy.^1,2,6

The pathogenesis of LyP remains unknown. Some have hypothesized a possible viral trigger; however, there is insufficient data to support this theory.^2,6 A diagnostic hallmark of LyP is its CD30 positivity, which is a known marker for T-cell activation.6 The spontaneous regression of skin lesions that is characteristic of LyP is believed to involve the interactions between CD30 and its ligand (CD30L), which may contribute to apoptosis of neoplastic T cells.^2,3,6 With regards to the possible mechanisms contributing to tumor progression in LyP, a mutation in the transforming growth factor β receptor gene on CD30+ tumor cells within LyP lesions may allow for these cells to evade growth regulation and progress to lymphoma.^2,6 A large percentage of LyP biopsy specimens show evidence of T-cell receptor gene monoclonal rearrangement, which can aid in establishing a diagnosis.^1,2

The histologic features of LyP can vary greatly depending on the age of the lesion sampled.^1,2 Histologic subtypes of LyP have been established, with type A being the most common (approximately 75% of cases), displaying a wedge-shaped infiltrate of scattered or clustered, large, atypical CD30+ T cells.^1,2 Types B through E vary in histologic features, with the exception that all subtypes contain a CD30+ lymphocytic infiltrate.^2,3

Treatment of LyP depends on the symptom/disease burden that the patient is experiencing. For patients with a limited number of nonscarring skin lesions in areas that are not cosmetically sensitive, observation is recommended. ^1-3 For symptomatic patients with an extensive number of lesions, particularly those that may be scarring and/or in cosmetically sensitive areas, low-dose oral methotrexate therapy is considered first-line treatment.^1-4 A methotrexate dose of 5 to 20 mg weekly can be effective in reducing the number and severity of lesions, with duration of treatment depending on clinical response.^1,2 For patients who have contraindications to or who cannot tolerate oral methotrexate, phototherapy using psoralen plus UVA twice weekly for 6 to 8 weeks is another treatment option.^1,2 Topical corticosteroids also can be used in children or for patients experiencing substantial pruritus.^1,2,4 Oral or topical retinoids, topical carmustine or mechlorethamine, and brentuximab (an anti-CD30 monoclonal antibody) are all alternative therapies that have shown some beneficial effects.^1,2 In the event that any of the skin lesions do not spontaneously regress within a 3- to 12-week time frame, surgical excision or radiotherapy can be performed on those lesions.²

Primary cutaneous anaplastic large cell lymphoma (C-ALCL) is another CD30+ lymphoproliferative disorder with overlapping clinical and histopathological features of LyP. Recurrent crops of multiple lesions favor a diagnosis of LyP, whereas solitary lesions favor C-ALCL; however, multifocal C-ALCL cases may occur.² Mycosis fungoides is the most common type of cutaneous T-cell lymphoma that characteristically presents in a patch, plaque, tumor progression. Although mycosis fungoides eventually may transform into a CD30⁺ lymphoma, our patient did not display the characteristic clinical progression to suggest this diagnosis. Pityriasis lichenoides et varioliformis acuta and pityriasis lichenoides chronica also fall into the spectrum of clonal T-cell cutaneous disorders that more commonly affect the pediatric population. Pityriasis lichenoides et varioliformis acuta has a marked CD8⁺ lymphocyte infiltrate, whereas pityriasis lichenoides chronica has more CD4⁺ lymphocytes. These disorders typically do not stain positive for CD30.²

All patients with a diagnosis of LyP should maintain lifelong, regular, 6- to 12-month follow-up visits to monitor disease status and screen for any evidence of developing malignancy.^1,2,6 A thorough review of clinical history, complete skin examination, and physical examination with a particular focus on detection of lymphadenopathy and hepatosplenomegaly should be included at every followup visit.1 Systemic symptoms such as fever, night sweats, or weight loss are not typical features of LyP; therefore, patients who begin to develop these symptoms should be promptly evaluated for systemic lymphoma.¹

To the Editor:

Intravascular large cell lymphoma (ILCL) is a rare B-cell lymphoma that is defined by the presence of large neoplastic B cells in the lumen of blood vessels.¹ At least 3 variants of ILCL have been described based on case reports and a small case series: classic, cutaneous, and hemophagocytic. The classic variant presents in elderly patients as nonspecific constitutional symptoms (fever or pain, or less frequently weight loss) or as signs of multiorgan failure (most commonly of the central nervous system). Skin involvement, which is present in nearly half of these patients, can take on multiple morphologies, including retiform purpura, ulcerated nodules, or pseudocellulitis. The cutaneous variant typically presents in middle-aged women with normal hematologic studies. Systemic involvement is less common in this variant of disease than the classic variant, which may partly explain why overall survival is superior in this variant. The hemophagocytic variant manifests as intravascular lymphoma accompanied by hemophagocytic syndrome (fever, hepatosplenomegaly, thrombocytopenia, and bone marrow involvement). Of the 3 variants, the hemophagocytic variant presents with the most rapid, aggressive decline, primarily in patients in Asian countries.¹ We describe a fatal case of classic ILCL, highlighting the importance of maintaining a high index of suspicion with false-negative biopsies.

A 69-year-old man presented to the emergency department for failure to thrive and nonhealing wounds of 1 year’s duration. His medical history was notable for poorly controlled diabetes mellitus, progressive multifocal ischemic and hemorrhagic cerebral infarcts, and bilateral deep venous thromboses. Physical examination revealed large purpuric to brown plaques in a retiform configuration with central necrotic eschars on the thighs and abdomen (Figure 1). There was no palpable lymphadenopathy. Laboratory tests revealed normocytic anemia with a hemoglobin level of 10.5 g/dL (reference range, 12–18 g/dL), elevated lactate dehydrogenase level of 525 U/L (reference range, 118–242 U/L), elevated erythrocyte sedimentation rate of 73 mm/h (reference range, <20 mm/h), antinuclear antibody (ANA) titer of 1:2560 (reference range, <1:80), and polyclonal hypergammaglobulinemia. The patient’s white blood cell and platelet counts, creatinine level, and liver function tests were within reference range. Cryoglobulins, coagulation studies, and cardiolipin antibodies were negative. Chest and abdominal imaging also were negative. An incisional skin biopsy and skin punch biopsy showed thrombotic coagulopathy and dilated vessels. A bone marrow biopsy revealed a hypercellular marrow but no plasma cell neoplasm. A repeat incisional skin biopsy demonstrated large CD20⁺ and CD45⁺ atypical lymphocytes within the small capillaries of the deep dermis and subcutaneous fat (Figure 2), which confirmed ILCL. Too deconditioned to tolerate chemotherapy, the patient opted for palliative care and died 18 months after initial presentation.

The diagnosis of ILCL often is delayed for several reasons.² Patients can present with a variety of signs and symptoms related to small vessel occlusion that can be misattributed to other conditions.^3,4 In our case, the patient’s recurrent infarcts were thought to be due to his poorly controlled diabetes mellitus, which was diagnosed a few weeks prior, and a positive ANA, even though the workup for antiphospholipid syndrome was negative. Interestingly, a positive ANA (without signs or symptoms of lupus or other autoimmune conditions) has been reported in patients with lymphoma.³ A positive antineutrophil cytoplasmic antibody level (without symptoms or other signs of vasculitis) has been reported in patients with ILCL.^4,5 Therefore, distractors are common.

Multiple incisional skin biopsies in the absence of clinical findings (ie, random skin biopsy) are moderately sensitive (77.8%) for the diagnosis of ILCL.² In a study by Matsue et al,² 111 suspected cases of ILCL underwent 3 incisional biopsies of fat-containing areas of the skin, such as the thigh, abdomen, and upper arm. Intravascular large cell lymphoma was confirmed in 26 cases. Seven additional cases were diagnosed as ILCL, 2 by additional skin biopsies (1 by a second round and 1 by a third round) and 5 by internal organ biopsy (4 bone marrow and 1 adrenal gland). The remaining cases ultimately were found to be a diagnostic mimicker of ILCL, including non-ILCL.² Although random skin biopsies are reasonably sensitive for ILCL, multiple biopsies are needed, and in some cases, sampling of an internal organ may be required to establish the diagnosis of ILCL.

The prognosis of ILCL is poor; the 3-year overall survival rate for classic and cutaneous variants is 22% and 56%, respectively.⁶ Anthracycline-based chemotherapy, such as CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone), is considered first-line treatment, and the addition of rituximab to the CHOP regimen may improve remission rates and survival.⁷

To the Editor:

Intravascular large cell lymphoma (ILCL) is a rare B-cell lymphoma that is defined by the presence of large neoplastic B cells in the lumen of blood vessels.¹ At least 3 variants of ILCL have been described based on case reports and a small case series: classic, cutaneous, and hemophagocytic. The classic variant presents in elderly patients as nonspecific constitutional symptoms (fever or pain, or less frequently weight loss) or as signs of multiorgan failure (most commonly of the central nervous system). Skin involvement, which is present in nearly half of these patients, can take on multiple morphologies, including retiform purpura, ulcerated nodules, or pseudocellulitis. The cutaneous variant typically presents in middle-aged women with normal hematologic studies. Systemic involvement is less common in this variant of disease than the classic variant, which may partly explain why overall survival is superior in this variant. The hemophagocytic variant manifests as intravascular lymphoma accompanied by hemophagocytic syndrome (fever, hepatosplenomegaly, thrombocytopenia, and bone marrow involvement). Of the 3 variants, the hemophagocytic variant presents with the most rapid, aggressive decline, primarily in patients in Asian countries.¹ We describe a fatal case of classic ILCL, highlighting the importance of maintaining a high index of suspicion with false-negative biopsies.

A 69-year-old man presented to the emergency department for failure to thrive and nonhealing wounds of 1 year’s duration. His medical history was notable for poorly controlled diabetes mellitus, progressive multifocal ischemic and hemorrhagic cerebral infarcts, and bilateral deep venous thromboses. Physical examination revealed large purpuric to brown plaques in a retiform configuration with central necrotic eschars on the thighs and abdomen (Figure 1). There was no palpable lymphadenopathy. Laboratory tests revealed normocytic anemia with a hemoglobin level of 10.5 g/dL (reference range, 12–18 g/dL), elevated lactate dehydrogenase level of 525 U/L (reference range, 118–242 U/L), elevated erythrocyte sedimentation rate of 73 mm/h (reference range, <20 mm/h), antinuclear antibody (ANA) titer of 1:2560 (reference range, <1:80), and polyclonal hypergammaglobulinemia. The patient’s white blood cell and platelet counts, creatinine level, and liver function tests were within reference range. Cryoglobulins, coagulation studies, and cardiolipin antibodies were negative. Chest and abdominal imaging also were negative. An incisional skin biopsy and skin punch biopsy showed thrombotic coagulopathy and dilated vessels. A bone marrow biopsy revealed a hypercellular marrow but no plasma cell neoplasm. A repeat incisional skin biopsy demonstrated large CD20⁺ and CD45⁺ atypical lymphocytes within the small capillaries of the deep dermis and subcutaneous fat (Figure 2), which confirmed ILCL. Too deconditioned to tolerate chemotherapy, the patient opted for palliative care and died 18 months after initial presentation.

The diagnosis of ILCL often is delayed for several reasons.² Patients can present with a variety of signs and symptoms related to small vessel occlusion that can be misattributed to other conditions.^3,4 In our case, the patient’s recurrent infarcts were thought to be due to his poorly controlled diabetes mellitus, which was diagnosed a few weeks prior, and a positive ANA, even though the workup for antiphospholipid syndrome was negative. Interestingly, a positive ANA (without signs or symptoms of lupus or other autoimmune conditions) has been reported in patients with lymphoma.³ A positive antineutrophil cytoplasmic antibody level (without symptoms or other signs of vasculitis) has been reported in patients with ILCL.^4,5 Therefore, distractors are common.

Multiple incisional skin biopsies in the absence of clinical findings (ie, random skin biopsy) are moderately sensitive (77.8%) for the diagnosis of ILCL.² In a study by Matsue et al,² 111 suspected cases of ILCL underwent 3 incisional biopsies of fat-containing areas of the skin, such as the thigh, abdomen, and upper arm. Intravascular large cell lymphoma was confirmed in 26 cases. Seven additional cases were diagnosed as ILCL, 2 by additional skin biopsies (1 by a second round and 1 by a third round) and 5 by internal organ biopsy (4 bone marrow and 1 adrenal gland). The remaining cases ultimately were found to be a diagnostic mimicker of ILCL, including non-ILCL.² Although random skin biopsies are reasonably sensitive for ILCL, multiple biopsies are needed, and in some cases, sampling of an internal organ may be required to establish the diagnosis of ILCL.

The prognosis of ILCL is poor; the 3-year overall survival rate for classic and cutaneous variants is 22% and 56%, respectively.⁶ Anthracycline-based chemotherapy, such as CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone), is considered first-line treatment, and the addition of rituximab to the CHOP regimen may improve remission rates and survival.⁷

To the Editor:

Intravascular large cell lymphoma (ILCL) is a rare B-cell lymphoma that is defined by the presence of large neoplastic B cells in the lumen of blood vessels.¹ At least 3 variants of ILCL have been described based on case reports and a small case series: classic, cutaneous, and hemophagocytic. The classic variant presents in elderly patients as nonspecific constitutional symptoms (fever or pain, or less frequently weight loss) or as signs of multiorgan failure (most commonly of the central nervous system). Skin involvement, which is present in nearly half of these patients, can take on multiple morphologies, including retiform purpura, ulcerated nodules, or pseudocellulitis. The cutaneous variant typically presents in middle-aged women with normal hematologic studies. Systemic involvement is less common in this variant of disease than the classic variant, which may partly explain why overall survival is superior in this variant. The hemophagocytic variant manifests as intravascular lymphoma accompanied by hemophagocytic syndrome (fever, hepatosplenomegaly, thrombocytopenia, and bone marrow involvement). Of the 3 variants, the hemophagocytic variant presents with the most rapid, aggressive decline, primarily in patients in Asian countries.¹ We describe a fatal case of classic ILCL, highlighting the importance of maintaining a high index of suspicion with false-negative biopsies.

A 69-year-old man presented to the emergency department for failure to thrive and nonhealing wounds of 1 year’s duration. His medical history was notable for poorly controlled diabetes mellitus, progressive multifocal ischemic and hemorrhagic cerebral infarcts, and bilateral deep venous thromboses. Physical examination revealed large purpuric to brown plaques in a retiform configuration with central necrotic eschars on the thighs and abdomen (Figure 1). There was no palpable lymphadenopathy. Laboratory tests revealed normocytic anemia with a hemoglobin level of 10.5 g/dL (reference range, 12–18 g/dL), elevated lactate dehydrogenase level of 525 U/L (reference range, 118–242 U/L), elevated erythrocyte sedimentation rate of 73 mm/h (reference range, <20 mm/h), antinuclear antibody (ANA) titer of 1:2560 (reference range, <1:80), and polyclonal hypergammaglobulinemia. The patient’s white blood cell and platelet counts, creatinine level, and liver function tests were within reference range. Cryoglobulins, coagulation studies, and cardiolipin antibodies were negative. Chest and abdominal imaging also were negative. An incisional skin biopsy and skin punch biopsy showed thrombotic coagulopathy and dilated vessels. A bone marrow biopsy revealed a hypercellular marrow but no plasma cell neoplasm. A repeat incisional skin biopsy demonstrated large CD20⁺ and CD45⁺ atypical lymphocytes within the small capillaries of the deep dermis and subcutaneous fat (Figure 2), which confirmed ILCL. Too deconditioned to tolerate chemotherapy, the patient opted for palliative care and died 18 months after initial presentation.

The diagnosis of ILCL often is delayed for several reasons.² Patients can present with a variety of signs and symptoms related to small vessel occlusion that can be misattributed to other conditions.^3,4 In our case, the patient’s recurrent infarcts were thought to be due to his poorly controlled diabetes mellitus, which was diagnosed a few weeks prior, and a positive ANA, even though the workup for antiphospholipid syndrome was negative. Interestingly, a positive ANA (without signs or symptoms of lupus or other autoimmune conditions) has been reported in patients with lymphoma.³ A positive antineutrophil cytoplasmic antibody level (without symptoms or other signs of vasculitis) has been reported in patients with ILCL.^4,5 Therefore, distractors are common.

Multiple incisional skin biopsies in the absence of clinical findings (ie, random skin biopsy) are moderately sensitive (77.8%) for the diagnosis of ILCL.² In a study by Matsue et al,² 111 suspected cases of ILCL underwent 3 incisional biopsies of fat-containing areas of the skin, such as the thigh, abdomen, and upper arm. Intravascular large cell lymphoma was confirmed in 26 cases. Seven additional cases were diagnosed as ILCL, 2 by additional skin biopsies (1 by a second round and 1 by a third round) and 5 by internal organ biopsy (4 bone marrow and 1 adrenal gland). The remaining cases ultimately were found to be a diagnostic mimicker of ILCL, including non-ILCL.² Although random skin biopsies are reasonably sensitive for ILCL, multiple biopsies are needed, and in some cases, sampling of an internal organ may be required to establish the diagnosis of ILCL.

The prognosis of ILCL is poor; the 3-year overall survival rate for classic and cutaneous variants is 22% and 56%, respectively.⁶ Anthracycline-based chemotherapy, such as CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone), is considered first-line treatment, and the addition of rituximab to the CHOP regimen may improve remission rates and survival.⁷

To the Editor:

Tumor necrosis factor α (TNF-α) inhibitor–induced lupuslike syndrome (TAILS) is a newly described entity that refers to the onset of subacute cutaneous lupus erythematosus (SCLE) during drug therapy with TNF-α antagonists. The condition is unique because it is thought to occur via a separate pathophysiologic mechanism than all other agents implicated in the development of drug-induced lupus erythematosus (DILE). Infliximab and etanercept are the 2 most common TNF-α antagonists associated with TAILS. Although rare, adalimumab, golimumab, and certolizumab pegol have been reported to induce this state of autoimmunity. We report an uncommon presentation of TAILS in a patient taking certolizumab pegol with a brief discussion of the pathogenesis underlying TAILS.

A 71-year-old woman presented to the dermatology clinic with a rash located on the arms, face, and trunk that she reported as having been present for months. She had a medical history of rheumatoid arthritis and currently was receiving certolizumab pegol injections. Physical examination revealed erythematous patches and plaques with overlying scaling and evidence of atrophic scarring on sun-exposed areas of the body. The lesions predominantly were in a symmetrical distribution across the extensor surfaces of both outer arms as well as the posterior superior thoracic region extending anteriorly along the bilateral supraclavicular area (Figures 1 and 2). A 4-mm punch biopsy was obtained and sent for histologic analysis, along with a sample of the patient’s serum for antinuclear antibody (ANA) testing.

Hematoxylin and eosin–stained tissue sections of the right superior thoracic lesions revealed epidermal atrophy, hyperkeratosis, and vacuolar alteration of the basal layer with apoptosis, consistent with a lichenoid tissue reaction. In addition, both superficial and deep perivascular and periadnexal lymphocytic infiltrates were observed as well as increased dermal mucin. Serologic testing was performed with a comprehensive ANA panel of the patient’s serum (Table). Of note, there was a speckled ANA pattern (1:1280), with elevated anti–double-stranded DNA (anti-dsDNA) and anti–Sjögren syndrome–related antigen A (anti-SSA)(also called anti-Ro antibodies) levels. The patient’s rheumatologist was consulted; certolizumab pegol was removed from the current drug regimen and switched to a daily regimen of hydroxychloroquine and prednisone. Seven weeks after discontinuation of certolizumab pegol, the patient was symptom free and without any cutaneous involvement. Based on the histologic analysis, presence of anti-SSA (Ro) autoantibodies, and the resolution of symptoms following withdrawal of anti–TNF-α therapy, a diagnosis of TAILS was made.

Subacute cutaneous lupus erythematosus, the most common subset of DILE, typically presents with annular polycyclic or papulosquamous skin eruptions on the legs; patients often test positive for anti-SSA/Ro and/or anti–Sjögren syndrome–related antigen B (also called anti-La) antibodies. Pharmaceutical agents linked to the development of SCLE are calcium channel blockers, angiotensin-converting enzyme inhibitors, thiazide diuretics, terbinafine, the chemotherapeutic agent gemcitabine, and TNF-α antagonists.^1,2 Tumor necrosis factor α antagonists are biologic agents that commonly are used in the management of systemic inflammatory diseases such as ulcerative colitis, Crohn disease, seronegative spondyloarthropathies, and rheumatoid arthritis. Among this family of therapeutics includes adalimumab (humanized monoclonal antibody), infliximab (chimeric monoclonal TNF-α antagonist), etanercept (soluble receptor fusion protein), certolizumab pegol (Fab fraction of a human IgG monoclonal antibody), and golimumab (humanized monoclonal antibody).

Tumor necrosis factor α inhibitor–induced lupuslike syndrome most commonly occurs in women in the fifth decade of life, and it is seen more often in those using infliximab or entanercept.³ Although reports do exist, TAILS rarely complicates treatment with adalimumab, golimumab, or certolizumab.^4,5 Due to the lack of reports, there are no diagnostic criteria nor an acceptable theory regarding the pathogenesis. In one study in France, the estimated incidence was thought to be 0.19% for infliximab and 0.18% for etanercept.⁶ Tumor necrosis factor α inhibitor–induced lupuslike syndrome is unique in that it is thought to occur by a different mechanism than that of other known offending agents in the development of DILE. Molecular mimicry, direct cytotoxicity, altered T-cell gene expression, and disruption of central immune tolerance have all been hypothesized to cause drug-induced systemic lupus erythematosus, SCLE, and chronic cutaneous lupus erythematosus. Tumor necrosis factor α inhibitors, are postulated to cause the induction of SCLE via an independent route separate from not only other drugs that cause SCLE but also all forms of DILE as a whole, making it a distinctive player within the realm of agents known to cause a lupuslike syndrome. The following hypotheses may explain this occurrence:

1. Increased humoral autoimmunity: Under normal circumstances, TNF-α activation leads to upregulation in the production of cytotoxic CD8⁺ T lymphocytes. The upregulation of CD8⁺ T lymphocytes concurrently leads to a simultaneous suppression of B lymphocytes. Inhibiting the effects of TNF-α on the other hand promotes cytotoxic T-lymphocyte suppression, leading to an increased synthesis of B cells and subsequently a state of increased humoral autoimmunity.⁷

2. Infection: The immunosuppressive effects of TNF-α inhibitors are well known, and the propensity to develop microbial infections, such as tuberculosis, is markedly increased on the use of these agents. Infections brought on by TNF-α inhibitor usage are hypothesized to induce a widespread activation of polyclonal B lymphocytes, eventually leading to the formation of antibodies against these polyclonal B lymphocytes and subsequently SCLE.⁸

3. Helper T cell (TH2) response: The inhibition of T_H1 CD4⁺ lymphocytes by TNF-α inversely leads to an increased production of T_H2 CD4⁺ lymphocytes. This increase in the levels of circulating T_H2 CD4⁺ lymphocytes brought on by the action of anti–TNF-α agents is thought to promote the development of SCLE.^9,10

4. Apoptosis theory: Molecules of TNF-α inhibitors are capable of binding to TNF-α receptors on the cell surface. In doing so, cellular apoptosis is triggered, resulting in the release of nucleosomal autoantigens from the apoptotic cells. In susceptible individuals, autoantibodies then begin to form against the nucleosomal autoantigens, leading to an autoimmune reaction that is characterized by SCLE.^11,12

Major histone compatibility (MHC) antigen testing performed by Sontheimer et al¹² established the presence of the HLA class I, HLA-B8, and/or HLA-DR3 haplotypes in patients with SCLE.^13,14 Furthermore, there is a well-known association between the antinuclear profile of known SCLE patients and the presence of anti-SSA (Ro) antibodies.¹³ Therefore, we propose that in susceptible individuals, such as those with the HLA class I, HLA-B8, or HLA-DR3 haplotypes, the initiation of a TNF-α inhibitor causes cellular apoptosis with the subsequent release of nucleosomal and cytoplasmic components (namely that of the Ro autoantigens), inducing a state of autoimmunity. An ensuing immunogenic response is then initiated in predisposed individuals for which anti-SSA (Ro) autoantibodies are produced against these previously mentioned autoantigens.

Drug-induced SCLE is most common in females (71%), with a median age of 58 years. The most common site of cutaneous manifestations is the legs.¹⁵ Although our patient was in the eighth decade of life with predominant cutaneous involvement of the upper extremity, the erythematous plaques with a symmetric, annular, polycyclic appearance in photosensitive regions raised a heightened suspicion for lupus erythematosus. Histology classically involves an interface dermatitis with vacuolar or hydropic change and lymphocytic infiltrates,¹⁶ consistent with the analysis of tissue sections from our patient. Moreover, the speckled ANA profile with positive anti-dsDNA and anti-SSA (Ro) antibodies in the absence of a negative rheumatoid factor and anticyclic citrullinated peptide antibodies strongly favored the diagnosis of SCLE over alternative diagnoses.²

The supraclavicular rash in our patient raises clinical suspicion for the shawl sign of dermatomyositis, which also is associated with musculoskeletal pain and photosensitivity. In addition, skin biopsy revealed vacuolar alteration of the basement membrane zoneand dermal mucin in both lupus erythematosus and dermatomyositis; therefore, skin biopsy is of little use in distinguishing the 2 conditions, and antibody testing must be performed. Although anti-SSA (Ro) antibodies commonly are associated with SCLE, there are reports involving positivity for the extractable nuclear antigen in cases of dermatomyositis.¹⁷ Based on our patient’s current drug regimen, including that of a known offending agent for SCLE, a presumptive diagnosis of TAILS was made. Following withdrawal of certolizumab pegol injections and subsequent resolution of the skin lesions, our patient was given a definitive diagnosis of TAILS based on clinical and pathological assessments.

The clinical diagnosis of TAILS should be made according to the triad of at least 1 serologic and 1 nonserologic American College of Rheumatology criteria, such as anti-SSA (Ro) antibodies and a photosensitive rash, respectively, as well as a relationship between the onset of symptoms and TNF-α inhibitor therapy.¹⁸ Both the definitive diagnosis and the treatment of TAILS can be made via withdrawal of the TNF-α inhibitor, which was true in our case whereby chronologically the onset of use with a TNF-α inhibitor was associated with disease onset. Furthermore, withdrawal led to complete improvement of all signs and symptoms, collectively supporting a diagnosis of TAILS. Notably, switching to a different TNF-α inhibitor has been shown to be safe and effective.¹⁹

To the Editor:

Tumor necrosis factor α (TNF-α) inhibitor–induced lupuslike syndrome (TAILS) is a newly described entity that refers to the onset of subacute cutaneous lupus erythematosus (SCLE) during drug therapy with TNF-α antagonists. The condition is unique because it is thought to occur via a separate pathophysiologic mechanism than all other agents implicated in the development of drug-induced lupus erythematosus (DILE). Infliximab and etanercept are the 2 most common TNF-α antagonists associated with TAILS. Although rare, adalimumab, golimumab, and certolizumab pegol have been reported to induce this state of autoimmunity. We report an uncommon presentation of TAILS in a patient taking certolizumab pegol with a brief discussion of the pathogenesis underlying TAILS.

A 71-year-old woman presented to the dermatology clinic with a rash located on the arms, face, and trunk that she reported as having been present for months. She had a medical history of rheumatoid arthritis and currently was receiving certolizumab pegol injections. Physical examination revealed erythematous patches and plaques with overlying scaling and evidence of atrophic scarring on sun-exposed areas of the body. The lesions predominantly were in a symmetrical distribution across the extensor surfaces of both outer arms as well as the posterior superior thoracic region extending anteriorly along the bilateral supraclavicular area (Figures 1 and 2). A 4-mm punch biopsy was obtained and sent for histologic analysis, along with a sample of the patient’s serum for antinuclear antibody (ANA) testing.

Hematoxylin and eosin–stained tissue sections of the right superior thoracic lesions revealed epidermal atrophy, hyperkeratosis, and vacuolar alteration of the basal layer with apoptosis, consistent with a lichenoid tissue reaction. In addition, both superficial and deep perivascular and periadnexal lymphocytic infiltrates were observed as well as increased dermal mucin. Serologic testing was performed with a comprehensive ANA panel of the patient’s serum (Table). Of note, there was a speckled ANA pattern (1:1280), with elevated anti–double-stranded DNA (anti-dsDNA) and anti–Sjögren syndrome–related antigen A (anti-SSA)(also called anti-Ro antibodies) levels. The patient’s rheumatologist was consulted; certolizumab pegol was removed from the current drug regimen and switched to a daily regimen of hydroxychloroquine and prednisone. Seven weeks after discontinuation of certolizumab pegol, the patient was symptom free and without any cutaneous involvement. Based on the histologic analysis, presence of anti-SSA (Ro) autoantibodies, and the resolution of symptoms following withdrawal of anti–TNF-α therapy, a diagnosis of TAILS was made.

Subacute cutaneous lupus erythematosus, the most common subset of DILE, typically presents with annular polycyclic or papulosquamous skin eruptions on the legs; patients often test positive for anti-SSA/Ro and/or anti–Sjögren syndrome–related antigen B (also called anti-La) antibodies. Pharmaceutical agents linked to the development of SCLE are calcium channel blockers, angiotensin-converting enzyme inhibitors, thiazide diuretics, terbinafine, the chemotherapeutic agent gemcitabine, and TNF-α antagonists.^1,2 Tumor necrosis factor α antagonists are biologic agents that commonly are used in the management of systemic inflammatory diseases such as ulcerative colitis, Crohn disease, seronegative spondyloarthropathies, and rheumatoid arthritis. Among this family of therapeutics includes adalimumab (humanized monoclonal antibody), infliximab (chimeric monoclonal TNF-α antagonist), etanercept (soluble receptor fusion protein), certolizumab pegol (Fab fraction of a human IgG monoclonal antibody), and golimumab (humanized monoclonal antibody).

Tumor necrosis factor α inhibitor–induced lupuslike syndrome most commonly occurs in women in the fifth decade of life, and it is seen more often in those using infliximab or entanercept.³ Although reports do exist, TAILS rarely complicates treatment with adalimumab, golimumab, or certolizumab.^4,5 Due to the lack of reports, there are no diagnostic criteria nor an acceptable theory regarding the pathogenesis. In one study in France, the estimated incidence was thought to be 0.19% for infliximab and 0.18% for etanercept.⁶ Tumor necrosis factor α inhibitor–induced lupuslike syndrome is unique in that it is thought to occur by a different mechanism than that of other known offending agents in the development of DILE. Molecular mimicry, direct cytotoxicity, altered T-cell gene expression, and disruption of central immune tolerance have all been hypothesized to cause drug-induced systemic lupus erythematosus, SCLE, and chronic cutaneous lupus erythematosus. Tumor necrosis factor α inhibitors, are postulated to cause the induction of SCLE via an independent route separate from not only other drugs that cause SCLE but also all forms of DILE as a whole, making it a distinctive player within the realm of agents known to cause a lupuslike syndrome. The following hypotheses may explain this occurrence:

1. Increased humoral autoimmunity: Under normal circumstances, TNF-α activation leads to upregulation in the production of cytotoxic CD8⁺ T lymphocytes. The upregulation of CD8⁺ T lymphocytes concurrently leads to a simultaneous suppression of B lymphocytes. Inhibiting the effects of TNF-α on the other hand promotes cytotoxic T-lymphocyte suppression, leading to an increased synthesis of B cells and subsequently a state of increased humoral autoimmunity.⁷

2. Infection: The immunosuppressive effects of TNF-α inhibitors are well known, and the propensity to develop microbial infections, such as tuberculosis, is markedly increased on the use of these agents. Infections brought on by TNF-α inhibitor usage are hypothesized to induce a widespread activation of polyclonal B lymphocytes, eventually leading to the formation of antibodies against these polyclonal B lymphocytes and subsequently SCLE.⁸

3. Helper T cell (TH2) response: The inhibition of T_H1 CD4⁺ lymphocytes by TNF-α inversely leads to an increased production of T_H2 CD4⁺ lymphocytes. This increase in the levels of circulating T_H2 CD4⁺ lymphocytes brought on by the action of anti–TNF-α agents is thought to promote the development of SCLE.^9,10

4. Apoptosis theory: Molecules of TNF-α inhibitors are capable of binding to TNF-α receptors on the cell surface. In doing so, cellular apoptosis is triggered, resulting in the release of nucleosomal autoantigens from the apoptotic cells. In susceptible individuals, autoantibodies then begin to form against the nucleosomal autoantigens, leading to an autoimmune reaction that is characterized by SCLE.^11,12

Major histone compatibility (MHC) antigen testing performed by Sontheimer et al¹² established the presence of the HLA class I, HLA-B8, and/or HLA-DR3 haplotypes in patients with SCLE.^13,14 Furthermore, there is a well-known association between the antinuclear profile of known SCLE patients and the presence of anti-SSA (Ro) antibodies.¹³ Therefore, we propose that in susceptible individuals, such as those with the HLA class I, HLA-B8, or HLA-DR3 haplotypes, the initiation of a TNF-α inhibitor causes cellular apoptosis with the subsequent release of nucleosomal and cytoplasmic components (namely that of the Ro autoantigens), inducing a state of autoimmunity. An ensuing immunogenic response is then initiated in predisposed individuals for which anti-SSA (Ro) autoantibodies are produced against these previously mentioned autoantigens.

Drug-induced SCLE is most common in females (71%), with a median age of 58 years. The most common site of cutaneous manifestations is the legs.¹⁵ Although our patient was in the eighth decade of life with predominant cutaneous involvement of the upper extremity, the erythematous plaques with a symmetric, annular, polycyclic appearance in photosensitive regions raised a heightened suspicion for lupus erythematosus. Histology classically involves an interface dermatitis with vacuolar or hydropic change and lymphocytic infiltrates,¹⁶ consistent with the analysis of tissue sections from our patient. Moreover, the speckled ANA profile with positive anti-dsDNA and anti-SSA (Ro) antibodies in the absence of a negative rheumatoid factor and anticyclic citrullinated peptide antibodies strongly favored the diagnosis of SCLE over alternative diagnoses.²

The supraclavicular rash in our patient raises clinical suspicion for the shawl sign of dermatomyositis, which also is associated with musculoskeletal pain and photosensitivity. In addition, skin biopsy revealed vacuolar alteration of the basement membrane zoneand dermal mucin in both lupus erythematosus and dermatomyositis; therefore, skin biopsy is of little use in distinguishing the 2 conditions, and antibody testing must be performed. Although anti-SSA (Ro) antibodies commonly are associated with SCLE, there are reports involving positivity for the extractable nuclear antigen in cases of dermatomyositis.¹⁷ Based on our patient’s current drug regimen, including that of a known offending agent for SCLE, a presumptive diagnosis of TAILS was made. Following withdrawal of certolizumab pegol injections and subsequent resolution of the skin lesions, our patient was given a definitive diagnosis of TAILS based on clinical and pathological assessments.

The clinical diagnosis of TAILS should be made according to the triad of at least 1 serologic and 1 nonserologic American College of Rheumatology criteria, such as anti-SSA (Ro) antibodies and a photosensitive rash, respectively, as well as a relationship between the onset of symptoms and TNF-α inhibitor therapy.¹⁸ Both the definitive diagnosis and the treatment of TAILS can be made via withdrawal of the TNF-α inhibitor, which was true in our case whereby chronologically the onset of use with a TNF-α inhibitor was associated with disease onset. Furthermore, withdrawal led to complete improvement of all signs and symptoms, collectively supporting a diagnosis of TAILS. Notably, switching to a different TNF-α inhibitor has been shown to be safe and effective.¹⁹

To the Editor:

Tumor necrosis factor α (TNF-α) inhibitor–induced lupuslike syndrome (TAILS) is a newly described entity that refers to the onset of subacute cutaneous lupus erythematosus (SCLE) during drug therapy with TNF-α antagonists. The condition is unique because it is thought to occur via a separate pathophysiologic mechanism than all other agents implicated in the development of drug-induced lupus erythematosus (DILE). Infliximab and etanercept are the 2 most common TNF-α antagonists associated with TAILS. Although rare, adalimumab, golimumab, and certolizumab pegol have been reported to induce this state of autoimmunity. We report an uncommon presentation of TAILS in a patient taking certolizumab pegol with a brief discussion of the pathogenesis underlying TAILS.

A 71-year-old woman presented to the dermatology clinic with a rash located on the arms, face, and trunk that she reported as having been present for months. She had a medical history of rheumatoid arthritis and currently was receiving certolizumab pegol injections. Physical examination revealed erythematous patches and plaques with overlying scaling and evidence of atrophic scarring on sun-exposed areas of the body. The lesions predominantly were in a symmetrical distribution across the extensor surfaces of both outer arms as well as the posterior superior thoracic region extending anteriorly along the bilateral supraclavicular area (Figures 1 and 2). A 4-mm punch biopsy was obtained and sent for histologic analysis, along with a sample of the patient’s serum for antinuclear antibody (ANA) testing.

Hematoxylin and eosin–stained tissue sections of the right superior thoracic lesions revealed epidermal atrophy, hyperkeratosis, and vacuolar alteration of the basal layer with apoptosis, consistent with a lichenoid tissue reaction. In addition, both superficial and deep perivascular and periadnexal lymphocytic infiltrates were observed as well as increased dermal mucin. Serologic testing was performed with a comprehensive ANA panel of the patient’s serum (Table). Of note, there was a speckled ANA pattern (1:1280), with elevated anti–double-stranded DNA (anti-dsDNA) and anti–Sjögren syndrome–related antigen A (anti-SSA)(also called anti-Ro antibodies) levels. The patient’s rheumatologist was consulted; certolizumab pegol was removed from the current drug regimen and switched to a daily regimen of hydroxychloroquine and prednisone. Seven weeks after discontinuation of certolizumab pegol, the patient was symptom free and without any cutaneous involvement. Based on the histologic analysis, presence of anti-SSA (Ro) autoantibodies, and the resolution of symptoms following withdrawal of anti–TNF-α therapy, a diagnosis of TAILS was made.

Subacute cutaneous lupus erythematosus, the most common subset of DILE, typically presents with annular polycyclic or papulosquamous skin eruptions on the legs; patients often test positive for anti-SSA/Ro and/or anti–Sjögren syndrome–related antigen B (also called anti-La) antibodies. Pharmaceutical agents linked to the development of SCLE are calcium channel blockers, angiotensin-converting enzyme inhibitors, thiazide diuretics, terbinafine, the chemotherapeutic agent gemcitabine, and TNF-α antagonists.^1,2 Tumor necrosis factor α antagonists are biologic agents that commonly are used in the management of systemic inflammatory diseases such as ulcerative colitis, Crohn disease, seronegative spondyloarthropathies, and rheumatoid arthritis. Among this family of therapeutics includes adalimumab (humanized monoclonal antibody), infliximab (chimeric monoclonal TNF-α antagonist), etanercept (soluble receptor fusion protein), certolizumab pegol (Fab fraction of a human IgG monoclonal antibody), and golimumab (humanized monoclonal antibody).

Tumor necrosis factor α inhibitor–induced lupuslike syndrome most commonly occurs in women in the fifth decade of life, and it is seen more often in those using infliximab or entanercept.³ Although reports do exist, TAILS rarely complicates treatment with adalimumab, golimumab, or certolizumab.^4,5 Due to the lack of reports, there are no diagnostic criteria nor an acceptable theory regarding the pathogenesis. In one study in France, the estimated incidence was thought to be 0.19% for infliximab and 0.18% for etanercept.⁶ Tumor necrosis factor α inhibitor–induced lupuslike syndrome is unique in that it is thought to occur by a different mechanism than that of other known offending agents in the development of DILE. Molecular mimicry, direct cytotoxicity, altered T-cell gene expression, and disruption of central immune tolerance have all been hypothesized to cause drug-induced systemic lupus erythematosus, SCLE, and chronic cutaneous lupus erythematosus. Tumor necrosis factor α inhibitors, are postulated to cause the induction of SCLE via an independent route separate from not only other drugs that cause SCLE but also all forms of DILE as a whole, making it a distinctive player within the realm of agents known to cause a lupuslike syndrome. The following hypotheses may explain this occurrence:

1. Increased humoral autoimmunity: Under normal circumstances, TNF-α activation leads to upregulation in the production of cytotoxic CD8⁺ T lymphocytes. The upregulation of CD8⁺ T lymphocytes concurrently leads to a simultaneous suppression of B lymphocytes. Inhibiting the effects of TNF-α on the other hand promotes cytotoxic T-lymphocyte suppression, leading to an increased synthesis of B cells and subsequently a state of increased humoral autoimmunity.⁷

2. Infection: The immunosuppressive effects of TNF-α inhibitors are well known, and the propensity to develop microbial infections, such as tuberculosis, is markedly increased on the use of these agents. Infections brought on by TNF-α inhibitor usage are hypothesized to induce a widespread activation of polyclonal B lymphocytes, eventually leading to the formation of antibodies against these polyclonal B lymphocytes and subsequently SCLE.⁸

3. Helper T cell (TH2) response: The inhibition of T_H1 CD4⁺ lymphocytes by TNF-α inversely leads to an increased production of T_H2 CD4⁺ lymphocytes. This increase in the levels of circulating T_H2 CD4⁺ lymphocytes brought on by the action of anti–TNF-α agents is thought to promote the development of SCLE.^9,10

4. Apoptosis theory: Molecules of TNF-α inhibitors are capable of binding to TNF-α receptors on the cell surface. In doing so, cellular apoptosis is triggered, resulting in the release of nucleosomal autoantigens from the apoptotic cells. In susceptible individuals, autoantibodies then begin to form against the nucleosomal autoantigens, leading to an autoimmune reaction that is characterized by SCLE.^11,12

Major histone compatibility (MHC) antigen testing performed by Sontheimer et al¹² established the presence of the HLA class I, HLA-B8, and/or HLA-DR3 haplotypes in patients with SCLE.^13,14 Furthermore, there is a well-known association between the antinuclear profile of known SCLE patients and the presence of anti-SSA (Ro) antibodies.¹³ Therefore, we propose that in susceptible individuals, such as those with the HLA class I, HLA-B8, or HLA-DR3 haplotypes, the initiation of a TNF-α inhibitor causes cellular apoptosis with the subsequent release of nucleosomal and cytoplasmic components (namely that of the Ro autoantigens), inducing a state of autoimmunity. An ensuing immunogenic response is then initiated in predisposed individuals for which anti-SSA (Ro) autoantibodies are produced against these previously mentioned autoantigens.

Drug-induced SCLE is most common in females (71%), with a median age of 58 years. The most common site of cutaneous manifestations is the legs.¹⁵ Although our patient was in the eighth decade of life with predominant cutaneous involvement of the upper extremity, the erythematous plaques with a symmetric, annular, polycyclic appearance in photosensitive regions raised a heightened suspicion for lupus erythematosus. Histology classically involves an interface dermatitis with vacuolar or hydropic change and lymphocytic infiltrates,¹⁶ consistent with the analysis of tissue sections from our patient. Moreover, the speckled ANA profile with positive anti-dsDNA and anti-SSA (Ro) antibodies in the absence of a negative rheumatoid factor and anticyclic citrullinated peptide antibodies strongly favored the diagnosis of SCLE over alternative diagnoses.²

The supraclavicular rash in our patient raises clinical suspicion for the shawl sign of dermatomyositis, which also is associated with musculoskeletal pain and photosensitivity. In addition, skin biopsy revealed vacuolar alteration of the basement membrane zoneand dermal mucin in both lupus erythematosus and dermatomyositis; therefore, skin biopsy is of little use in distinguishing the 2 conditions, and antibody testing must be performed. Although anti-SSA (Ro) antibodies commonly are associated with SCLE, there are reports involving positivity for the extractable nuclear antigen in cases of dermatomyositis.¹⁷ Based on our patient’s current drug regimen, including that of a known offending agent for SCLE, a presumptive diagnosis of TAILS was made. Following withdrawal of certolizumab pegol injections and subsequent resolution of the skin lesions, our patient was given a definitive diagnosis of TAILS based on clinical and pathological assessments.

The clinical diagnosis of TAILS should be made according to the triad of at least 1 serologic and 1 nonserologic American College of Rheumatology criteria, such as anti-SSA (Ro) antibodies and a photosensitive rash, respectively, as well as a relationship between the onset of symptoms and TNF-α inhibitor therapy.¹⁸ Both the definitive diagnosis and the treatment of TAILS can be made via withdrawal of the TNF-α inhibitor, which was true in our case whereby chronologically the onset of use with a TNF-α inhibitor was associated with disease onset. Furthermore, withdrawal led to complete improvement of all signs and symptoms, collectively supporting a diagnosis of TAILS. Notably, switching to a different TNF-α inhibitor has been shown to be safe and effective.¹⁹

The Diagnosis: Granuloma Annulare

A biopsy of a lesion on the right flank demonstrated granulomatous inflammation and interstitial mucin (Figure), characteristic of granuloma annulare (GA).^1,2 Granuloma annulare is a relatively common skin disorder with an unknown etiology. It typically presents as smooth, annular, erythematous plaques.¹ The most common variants of GA are localized, generalized, and subcutaneous. Our case demonstrated Wolf isotopic response, an unrelated skin disease that forms at the same location as a previously healed skin lesion.² It is important to be aware of this phenomenon so that it is not confused with a recurrence of herpes zoster virus (HZV).

Although relatively infrequent, GA is the most common isotopic response following HZV infections.^3-5 Other postherpetic isotopic eruptions include cutaneous malignancies, lichen planus, sarcoidosis, morphea, reactive perforating collagenosis, psoriasis, and infections, among others.^3,5,6 The time between HZV infection and GA can be variable, ranging from a few weeks to many years apart.³

Oftentimes GA will spontaneously resolve within 2 years; however, recurrence is common.^7-9 There currently are no standard treatment guidelines. The most promising treatment options include intralesional or topical glucocorticoids for localized GA as well as phototherapy or hydroxychloroquine for widespread disease.^8,10  

Annular elastolytic giant cell granuloma (also called actinic granuloma) is a rare idiopathic inflammatory skin disease. It is characterized by erythematous annular papules or plaques mainly found on sun-exposed skin, such as the backs of the hands, forearms, or face.^11,12 Therefore, based on the distribution of our patient’s lesions, annular elastolytic giant cell granuloma was an unlikely diagnosis. Furthermore, it is not a known postherpetic isotopic reaction. Annular elastolytic giant cell granuloma can appear histologically similar to GA. Differentiating histologic features include a nonpalisading granuloma as well as the absence of mucin and necrobiosis.¹²

Annular lichen planus is a long-recognized but uncommon clinical variant of lichen planus that typically presents as pruritic, purple, annular plaques on the penis, scrotum, or intertriginous areas.¹³ The violaceous coloring is more characteristic of lichen planus. Histology is helpful in differentiating from GA.

Nummular eczema presents as scattered, welldefined, pruritic, erythematous, coin-shaped, coin-sized plaques in patients with diffusely dry skin.¹⁴ The scaling and serous crusting as well as more prominent pruritus help distinguish it from GA. The appearance of nummular eczema is quite characteristic; therefore, a biopsy typically is unnecessary for diagnosis. However, a potassium hydroxide wet mount examination of a skin scraping should be performed if tinea corporis also is suspected.

Superficial erythema annulare centrifugum classically presents as an annular or arciform pruritic lesion with an advancing outer erythematous edge with an inner rim of scale that most commonly occurs on the lower extremities. ¹⁵ The presence of pruritus and trailing scale helps distinguish this lesion from GA. Histologically, there are epidermal changes of hyperplasia, spongiosis, and parakeratosis, as well as lymphohistiocytic infiltrate surrounding the superficial dermal vessels^.16

We report this case to highlight GA as the most common postherpetic isotopic response. It should be on the differential diagnosis when a patient presents with erythematous, smooth, annular plaques occurring in the distribution of a resolved case of HZV.

The Diagnosis: Granuloma Annulare

A biopsy of a lesion on the right flank demonstrated granulomatous inflammation and interstitial mucin (Figure), characteristic of granuloma annulare (GA).^1,2 Granuloma annulare is a relatively common skin disorder with an unknown etiology. It typically presents as smooth, annular, erythematous plaques.¹ The most common variants of GA are localized, generalized, and subcutaneous. Our case demonstrated Wolf isotopic response, an unrelated skin disease that forms at the same location as a previously healed skin lesion.² It is important to be aware of this phenomenon so that it is not confused with a recurrence of herpes zoster virus (HZV).

Although relatively infrequent, GA is the most common isotopic response following HZV infections.^3-5 Other postherpetic isotopic eruptions include cutaneous malignancies, lichen planus, sarcoidosis, morphea, reactive perforating collagenosis, psoriasis, and infections, among others.^3,5,6 The time between HZV infection and GA can be variable, ranging from a few weeks to many years apart.³

Oftentimes GA will spontaneously resolve within 2 years; however, recurrence is common.^7-9 There currently are no standard treatment guidelines. The most promising treatment options include intralesional or topical glucocorticoids for localized GA as well as phototherapy or hydroxychloroquine for widespread disease.^8,10  

Annular elastolytic giant cell granuloma (also called actinic granuloma) is a rare idiopathic inflammatory skin disease. It is characterized by erythematous annular papules or plaques mainly found on sun-exposed skin, such as the backs of the hands, forearms, or face.^11,12 Therefore, based on the distribution of our patient’s lesions, annular elastolytic giant cell granuloma was an unlikely diagnosis. Furthermore, it is not a known postherpetic isotopic reaction. Annular elastolytic giant cell granuloma can appear histologically similar to GA. Differentiating histologic features include a nonpalisading granuloma as well as the absence of mucin and necrobiosis.¹²

Annular lichen planus is a long-recognized but uncommon clinical variant of lichen planus that typically presents as pruritic, purple, annular plaques on the penis, scrotum, or intertriginous areas.¹³ The violaceous coloring is more characteristic of lichen planus. Histology is helpful in differentiating from GA.

Nummular eczema presents as scattered, welldefined, pruritic, erythematous, coin-shaped, coin-sized plaques in patients with diffusely dry skin.¹⁴ The scaling and serous crusting as well as more prominent pruritus help distinguish it from GA. The appearance of nummular eczema is quite characteristic; therefore, a biopsy typically is unnecessary for diagnosis. However, a potassium hydroxide wet mount examination of a skin scraping should be performed if tinea corporis also is suspected.

Superficial erythema annulare centrifugum classically presents as an annular or arciform pruritic lesion with an advancing outer erythematous edge with an inner rim of scale that most commonly occurs on the lower extremities. ¹⁵ The presence of pruritus and trailing scale helps distinguish this lesion from GA. Histologically, there are epidermal changes of hyperplasia, spongiosis, and parakeratosis, as well as lymphohistiocytic infiltrate surrounding the superficial dermal vessels^.16

We report this case to highlight GA as the most common postherpetic isotopic response. It should be on the differential diagnosis when a patient presents with erythematous, smooth, annular plaques occurring in the distribution of a resolved case of HZV.

The Diagnosis: Granuloma Annulare

A biopsy of a lesion on the right flank demonstrated granulomatous inflammation and interstitial mucin (Figure), characteristic of granuloma annulare (GA).^1,2 Granuloma annulare is a relatively common skin disorder with an unknown etiology. It typically presents as smooth, annular, erythematous plaques.¹ The most common variants of GA are localized, generalized, and subcutaneous. Our case demonstrated Wolf isotopic response, an unrelated skin disease that forms at the same location as a previously healed skin lesion.² It is important to be aware of this phenomenon so that it is not confused with a recurrence of herpes zoster virus (HZV).

Although relatively infrequent, GA is the most common isotopic response following HZV infections.^3-5 Other postherpetic isotopic eruptions include cutaneous malignancies, lichen planus, sarcoidosis, morphea, reactive perforating collagenosis, psoriasis, and infections, among others.^3,5,6 The time between HZV infection and GA can be variable, ranging from a few weeks to many years apart.³

Oftentimes GA will spontaneously resolve within 2 years; however, recurrence is common.^7-9 There currently are no standard treatment guidelines. The most promising treatment options include intralesional or topical glucocorticoids for localized GA as well as phototherapy or hydroxychloroquine for widespread disease.^8,10  

Annular elastolytic giant cell granuloma (also called actinic granuloma) is a rare idiopathic inflammatory skin disease. It is characterized by erythematous annular papules or plaques mainly found on sun-exposed skin, such as the backs of the hands, forearms, or face.^11,12 Therefore, based on the distribution of our patient’s lesions, annular elastolytic giant cell granuloma was an unlikely diagnosis. Furthermore, it is not a known postherpetic isotopic reaction. Annular elastolytic giant cell granuloma can appear histologically similar to GA. Differentiating histologic features include a nonpalisading granuloma as well as the absence of mucin and necrobiosis.¹²

Annular lichen planus is a long-recognized but uncommon clinical variant of lichen planus that typically presents as pruritic, purple, annular plaques on the penis, scrotum, or intertriginous areas.¹³ The violaceous coloring is more characteristic of lichen planus. Histology is helpful in differentiating from GA.

Nummular eczema presents as scattered, welldefined, pruritic, erythematous, coin-shaped, coin-sized plaques in patients with diffusely dry skin.¹⁴ The scaling and serous crusting as well as more prominent pruritus help distinguish it from GA. The appearance of nummular eczema is quite characteristic; therefore, a biopsy typically is unnecessary for diagnosis. However, a potassium hydroxide wet mount examination of a skin scraping should be performed if tinea corporis also is suspected.

Superficial erythema annulare centrifugum classically presents as an annular or arciform pruritic lesion with an advancing outer erythematous edge with an inner rim of scale that most commonly occurs on the lower extremities. ¹⁵ The presence of pruritus and trailing scale helps distinguish this lesion from GA. Histologically, there are epidermal changes of hyperplasia, spongiosis, and parakeratosis, as well as lymphohistiocytic infiltrate surrounding the superficial dermal vessels^.16

We report this case to highlight GA as the most common postherpetic isotopic response. It should be on the differential diagnosis when a patient presents with erythematous, smooth, annular plaques occurring in the distribution of a resolved case of HZV.

The Diagnosis: Proximal-Type Epithelioid Sarcoma

Proximal-type epithelioid sarcoma (PES) is a rare high-grade sarcoma of uncertain histogenesis that may present with a benign clinical appearance. Proximal-type epithelioid sarcoma peaks at 20 to 40 years of age and has a slight male predominance. This tumor exhibits aggressive behavior with both local recurrence and metastasis.¹ The average overall survival is poor; however, tumor size less than 5 cm and complete excision with tumor-free margin status improves the prognosis.² Proximal-type epithelioid sarcoma should not be confused with distal-type epithelioid sarcoma, which has a better prognosis and occurs in younger patients.¹ Treatment of PES is wide excision, and chemotherapy trials with tazemetostat are ongoing.³

The deceptively banal clinical appearance of PES may delay appropriate diagnosis and treatment. Proximal-type epithelioid sarcoma often grows in sheets (quiz image [top] inset) and loose nests1 but also may take on a more corded appearance mimicking myoepithelial carcinoma. The cells themselves are plump dyscohesive epithelioid cells (quiz image [top]) with large nucleoli and eosinophilic cytoplasm or hyaline globules1 (quiz image [bottom]), but cells also may be focally spindled. Myxoid stroma, hemorrhage, and necrosis often are prominent features. Epithelioid sarcomas characteristically demonstrate positive immunostaining for both epithelial and mesenchymal markers (pan-cytokeratin and vimentin),¹ with the majority having loss of expression of integrase interactor 1 (INI-1).² Histology in this case was positive for cytokeratin monoclonal antibodies CAM5.2 and OSCAR, epithelial membrane antigen, and vimentin; it showed loss of INI-1 staining (quiz image [bottom]). Negative stains included S-100, p63, cytokeratins 7 and 20, CD34, CD31, ERG, glial fibrillary acidic protein, transducin-like enhancer of split 1, CD117, myogenin, synaptophysin, chromogranin, CD10, inhibin, CD99, and estrogen receptor.

The differential diagnosis of PES includes poorly differentiated squamous cell carcinoma (Figure 1 [inset]), melanoma, myoepithelial carcinoma, and epithelioid angiosarcoma. Primary squamous cell carcinoma of the vulva presents as an endophytic or exophytic mass with raised borders. Vulvar cancer is uncommon among gynecologic malignancies, with squamous cell carcinoma being the most commonly encountered.⁴ Vulvar intraepithelial neoplasia (VIN) is increasing in incidence, while the occurrence of invasive squamous cell carcinoma remains stable.⁵ Human papillomavirus–related VIN (usual-type VIN) is less likely to progress to squamous cell carcinoma than differentiated VIN (d-VIN), a dysplasia that is unrelated to human papillomavirus that frequently harbors p53 mutations.⁴ The presence of histologic epidermal involvement can help distinguish squamous cell carcinoma from PES (Figure 1). As opposed to PES, metastatic squamous cell carcinoma is characterized by intercellular bridges and often at least focal keratinization (Figure 1). Squamous cell carcinoma demonstrates positivity with p63 and p40 immunohistochemical stains, while PES rarely stains for either.⁶

Melanoma is the second most common vulvar malignancy. Vulvar melanoma tends to occur in women of advanced age but has been reported in girls as young as 10 years old.⁷ There is some evidence that patients with lichen sclerosus may be at an increased risk for the development of vulvar melanoma.⁸ Compared to PES, primary vulvar melanoma usually demonstrates epidermal involvement as well as clinical findings of a pigmented lesion (Figure 2). A notable minority of vulvar melanomas are amelanotic.⁹ Melanoma may be distinguished from PES with a panel of melanocytic markers—human melanoma black 45, Melan-A, SRY-box transcription factor 10, S-100, and microphthalmia transcription factor—that rarely are expressed in the latter. Both PES and rhabdoid melanoma have eosinophilic and tinctorial cytoplasmic inclusions.¹⁰ Melanin pigment and more cohesive nests are helpful clues that may point to melanoma when present.

Myoepithelial carcinoma of the vulva is rare.¹¹ Myoepithelial carcinoma of soft tissue is more aggressive than its benign counterpart, with up to a 50% metastasis rate.¹² The presence of prominent corded or trabecular growth in a myxoid or hyaline background may point to the diagnosis (Figure 3). Similar to PES, myoepithelial carcinoma may lose expression of nuclear INI-1, while myoepithelial carcinoma is more likely to express S-100 and glial fibrillary acidic protein.¹³ Rearrangements of EWS RNA binding protein 1, EWSR1, have been found in half of myoepithelial neoplasms.¹²

Angiosarcomas represent 5% of cutaneous sarcomas and rarely have been reported in the vulva, primarily occurring in the setting of long-standing lymphedema and radiation.¹⁴ Angiosarcoma more often occurs on the head and neck, breasts, or extremities. Additional risk factors for the development of angiosarcoma include toxin exposure (eg, polyvinyl chloride, thorium dioxide, arsenic), anabolic steroids, and filariasis, as well as genetic disorders (eg, neurofibromatosis type 1, BRCA gene mutations, Maffucci syndrome).¹⁵ Epithelioid angiosarcoma is an infiltrative tumor composed of irregular anastomosing vascular channels with extravasated erythrocytes (Figure 4). Solid growth and necrosis may be present in more aggressive tumors. The cells themselves are pleomorphic endothelial cells with vesicular chromatin and prominent nucleoli. Epithelioid angiosarcoma may resemble carcinoma and have focal keratin expression. However, the characteristic eosinophilic cytoplasm seen in PES should not be identified in epithelioid angiosarcoma. Unlike PES, epithelioid angiosarcoma is positive for CD31 and has retained expression for INI-1. Both angiosarcoma and proximal-type epithelioid sarcoma may express vascular markers CD34 and FLI-1¹⁶; thus an expanded panel of immunohistochemical studies may be of utility.

The Diagnosis: Proximal-Type Epithelioid Sarcoma

Proximal-type epithelioid sarcoma (PES) is a rare high-grade sarcoma of uncertain histogenesis that may present with a benign clinical appearance. Proximal-type epithelioid sarcoma peaks at 20 to 40 years of age and has a slight male predominance. This tumor exhibits aggressive behavior with both local recurrence and metastasis.¹ The average overall survival is poor; however, tumor size less than 5 cm and complete excision with tumor-free margin status improves the prognosis.² Proximal-type epithelioid sarcoma should not be confused with distal-type epithelioid sarcoma, which has a better prognosis and occurs in younger patients.¹ Treatment of PES is wide excision, and chemotherapy trials with tazemetostat are ongoing.³

The deceptively banal clinical appearance of PES may delay appropriate diagnosis and treatment. Proximal-type epithelioid sarcoma often grows in sheets (quiz image [top] inset) and loose nests1 but also may take on a more corded appearance mimicking myoepithelial carcinoma. The cells themselves are plump dyscohesive epithelioid cells (quiz image [top]) with large nucleoli and eosinophilic cytoplasm or hyaline globules1 (quiz image [bottom]), but cells also may be focally spindled. Myxoid stroma, hemorrhage, and necrosis often are prominent features. Epithelioid sarcomas characteristically demonstrate positive immunostaining for both epithelial and mesenchymal markers (pan-cytokeratin and vimentin),¹ with the majority having loss of expression of integrase interactor 1 (INI-1).² Histology in this case was positive for cytokeratin monoclonal antibodies CAM5.2 and OSCAR, epithelial membrane antigen, and vimentin; it showed loss of INI-1 staining (quiz image [bottom]). Negative stains included S-100, p63, cytokeratins 7 and 20, CD34, CD31, ERG, glial fibrillary acidic protein, transducin-like enhancer of split 1, CD117, myogenin, synaptophysin, chromogranin, CD10, inhibin, CD99, and estrogen receptor.

The differential diagnosis of PES includes poorly differentiated squamous cell carcinoma (Figure 1 [inset]), melanoma, myoepithelial carcinoma, and epithelioid angiosarcoma. Primary squamous cell carcinoma of the vulva presents as an endophytic or exophytic mass with raised borders. Vulvar cancer is uncommon among gynecologic malignancies, with squamous cell carcinoma being the most commonly encountered.⁴ Vulvar intraepithelial neoplasia (VIN) is increasing in incidence, while the occurrence of invasive squamous cell carcinoma remains stable.⁵ Human papillomavirus–related VIN (usual-type VIN) is less likely to progress to squamous cell carcinoma than differentiated VIN (d-VIN), a dysplasia that is unrelated to human papillomavirus that frequently harbors p53 mutations.⁴ The presence of histologic epidermal involvement can help distinguish squamous cell carcinoma from PES (Figure 1). As opposed to PES, metastatic squamous cell carcinoma is characterized by intercellular bridges and often at least focal keratinization (Figure 1). Squamous cell carcinoma demonstrates positivity with p63 and p40 immunohistochemical stains, while PES rarely stains for either.⁶

Melanoma is the second most common vulvar malignancy. Vulvar melanoma tends to occur in women of advanced age but has been reported in girls as young as 10 years old.⁷ There is some evidence that patients with lichen sclerosus may be at an increased risk for the development of vulvar melanoma.⁸ Compared to PES, primary vulvar melanoma usually demonstrates epidermal involvement as well as clinical findings of a pigmented lesion (Figure 2). A notable minority of vulvar melanomas are amelanotic.⁹ Melanoma may be distinguished from PES with a panel of melanocytic markers—human melanoma black 45, Melan-A, SRY-box transcription factor 10, S-100, and microphthalmia transcription factor—that rarely are expressed in the latter. Both PES and rhabdoid melanoma have eosinophilic and tinctorial cytoplasmic inclusions.¹⁰ Melanin pigment and more cohesive nests are helpful clues that may point to melanoma when present.

Myoepithelial carcinoma of the vulva is rare.¹¹ Myoepithelial carcinoma of soft tissue is more aggressive than its benign counterpart, with up to a 50% metastasis rate.¹² The presence of prominent corded or trabecular growth in a myxoid or hyaline background may point to the diagnosis (Figure 3). Similar to PES, myoepithelial carcinoma may lose expression of nuclear INI-1, while myoepithelial carcinoma is more likely to express S-100 and glial fibrillary acidic protein.¹³ Rearrangements of EWS RNA binding protein 1, EWSR1, have been found in half of myoepithelial neoplasms.¹²

Angiosarcomas represent 5% of cutaneous sarcomas and rarely have been reported in the vulva, primarily occurring in the setting of long-standing lymphedema and radiation.¹⁴ Angiosarcoma more often occurs on the head and neck, breasts, or extremities. Additional risk factors for the development of angiosarcoma include toxin exposure (eg, polyvinyl chloride, thorium dioxide, arsenic), anabolic steroids, and filariasis, as well as genetic disorders (eg, neurofibromatosis type 1, BRCA gene mutations, Maffucci syndrome).¹⁵ Epithelioid angiosarcoma is an infiltrative tumor composed of irregular anastomosing vascular channels with extravasated erythrocytes (Figure 4). Solid growth and necrosis may be present in more aggressive tumors. The cells themselves are pleomorphic endothelial cells with vesicular chromatin and prominent nucleoli. Epithelioid angiosarcoma may resemble carcinoma and have focal keratin expression. However, the characteristic eosinophilic cytoplasm seen in PES should not be identified in epithelioid angiosarcoma. Unlike PES, epithelioid angiosarcoma is positive for CD31 and has retained expression for INI-1. Both angiosarcoma and proximal-type epithelioid sarcoma may express vascular markers CD34 and FLI-1¹⁶; thus an expanded panel of immunohistochemical studies may be of utility.

The Diagnosis: Proximal-Type Epithelioid Sarcoma

Proximal-type epithelioid sarcoma (PES) is a rare high-grade sarcoma of uncertain histogenesis that may present with a benign clinical appearance. Proximal-type epithelioid sarcoma peaks at 20 to 40 years of age and has a slight male predominance. This tumor exhibits aggressive behavior with both local recurrence and metastasis.¹ The average overall survival is poor; however, tumor size less than 5 cm and complete excision with tumor-free margin status improves the prognosis.² Proximal-type epithelioid sarcoma should not be confused with distal-type epithelioid sarcoma, which has a better prognosis and occurs in younger patients.¹ Treatment of PES is wide excision, and chemotherapy trials with tazemetostat are ongoing.³

The deceptively banal clinical appearance of PES may delay appropriate diagnosis and treatment. Proximal-type epithelioid sarcoma often grows in sheets (quiz image [top] inset) and loose nests1 but also may take on a more corded appearance mimicking myoepithelial carcinoma. The cells themselves are plump dyscohesive epithelioid cells (quiz image [top]) with large nucleoli and eosinophilic cytoplasm or hyaline globules1 (quiz image [bottom]), but cells also may be focally spindled. Myxoid stroma, hemorrhage, and necrosis often are prominent features. Epithelioid sarcomas characteristically demonstrate positive immunostaining for both epithelial and mesenchymal markers (pan-cytokeratin and vimentin),¹ with the majority having loss of expression of integrase interactor 1 (INI-1).² Histology in this case was positive for cytokeratin monoclonal antibodies CAM5.2 and OSCAR, epithelial membrane antigen, and vimentin; it showed loss of INI-1 staining (quiz image [bottom]). Negative stains included S-100, p63, cytokeratins 7 and 20, CD34, CD31, ERG, glial fibrillary acidic protein, transducin-like enhancer of split 1, CD117, myogenin, synaptophysin, chromogranin, CD10, inhibin, CD99, and estrogen receptor.

The differential diagnosis of PES includes poorly differentiated squamous cell carcinoma (Figure 1 [inset]), melanoma, myoepithelial carcinoma, and epithelioid angiosarcoma. Primary squamous cell carcinoma of the vulva presents as an endophytic or exophytic mass with raised borders. Vulvar cancer is uncommon among gynecologic malignancies, with squamous cell carcinoma being the most commonly encountered.⁴ Vulvar intraepithelial neoplasia (VIN) is increasing in incidence, while the occurrence of invasive squamous cell carcinoma remains stable.⁵ Human papillomavirus–related VIN (usual-type VIN) is less likely to progress to squamous cell carcinoma than differentiated VIN (d-VIN), a dysplasia that is unrelated to human papillomavirus that frequently harbors p53 mutations.⁴ The presence of histologic epidermal involvement can help distinguish squamous cell carcinoma from PES (Figure 1). As opposed to PES, metastatic squamous cell carcinoma is characterized by intercellular bridges and often at least focal keratinization (Figure 1). Squamous cell carcinoma demonstrates positivity with p63 and p40 immunohistochemical stains, while PES rarely stains for either.⁶

Melanoma is the second most common vulvar malignancy. Vulvar melanoma tends to occur in women of advanced age but has been reported in girls as young as 10 years old.⁷ There is some evidence that patients with lichen sclerosus may be at an increased risk for the development of vulvar melanoma.⁸ Compared to PES, primary vulvar melanoma usually demonstrates epidermal involvement as well as clinical findings of a pigmented lesion (Figure 2). A notable minority of vulvar melanomas are amelanotic.⁹ Melanoma may be distinguished from PES with a panel of melanocytic markers—human melanoma black 45, Melan-A, SRY-box transcription factor 10, S-100, and microphthalmia transcription factor—that rarely are expressed in the latter. Both PES and rhabdoid melanoma have eosinophilic and tinctorial cytoplasmic inclusions.¹⁰ Melanin pigment and more cohesive nests are helpful clues that may point to melanoma when present.

Myoepithelial carcinoma of the vulva is rare.¹¹ Myoepithelial carcinoma of soft tissue is more aggressive than its benign counterpart, with up to a 50% metastasis rate.¹² The presence of prominent corded or trabecular growth in a myxoid or hyaline background may point to the diagnosis (Figure 3). Similar to PES, myoepithelial carcinoma may lose expression of nuclear INI-1, while myoepithelial carcinoma is more likely to express S-100 and glial fibrillary acidic protein.¹³ Rearrangements of EWS RNA binding protein 1, EWSR1, have been found in half of myoepithelial neoplasms.¹²

Angiosarcomas represent 5% of cutaneous sarcomas and rarely have been reported in the vulva, primarily occurring in the setting of long-standing lymphedema and radiation.¹⁴ Angiosarcoma more often occurs on the head and neck, breasts, or extremities. Additional risk factors for the development of angiosarcoma include toxin exposure (eg, polyvinyl chloride, thorium dioxide, arsenic), anabolic steroids, and filariasis, as well as genetic disorders (eg, neurofibromatosis type 1, BRCA gene mutations, Maffucci syndrome).¹⁵ Epithelioid angiosarcoma is an infiltrative tumor composed of irregular anastomosing vascular channels with extravasated erythrocytes (Figure 4). Solid growth and necrosis may be present in more aggressive tumors. The cells themselves are pleomorphic endothelial cells with vesicular chromatin and prominent nucleoli. Epithelioid angiosarcoma may resemble carcinoma and have focal keratin expression. However, the characteristic eosinophilic cytoplasm seen in PES should not be identified in epithelioid angiosarcoma. Unlike PES, epithelioid angiosarcoma is positive for CD31 and has retained expression for INI-1. Both angiosarcoma and proximal-type epithelioid sarcoma may express vascular markers CD34 and FLI-1¹⁶; thus an expanded panel of immunohistochemical studies may be of utility.