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The Diagnosis: Cutaneous Angiosarcoma 

Biopsy revealed a cellular neoplasm consisting of atypical polygonal cells with a hobnailed appearance, vasoformative characteristics, and rare extravasated erythrocytes. The tumor had an infiltrative growth pattern as demonstrated by dissecting dermal collagen and a poorly defined border with adjacent normal tissue (Figure 1). Immunohistochemistry revealed that the lesion was positive for CD31 and D2-40 (Figure 2) but negative for cytokeratin, CD10, CD68, human herpesvirus 8, CD34, and Melan A, thus confirming the endothelial origin of the tumor cells and the diagnosis of cutaneous angiosarcoma (CAS). The patient was treated with extended surgical excision and radiation therapy. No recurrence or metastasis was found throughout 2 years of follow-up.  

Radical resection with a negative margin is considered the first-line treatment of choice. Although there is a paucity of studies assessing the specific width of surgical margins, application of no less than a 3-cm peripheral margin as well as a clear deep margin is recommended.⁵ Adjuvant radiation therapy also is essential to prevent local recurrence. Patients receiving combination therapy have a superior overall survival rate when compared to those undergoing surgery or radiation therapy alone.⁴  

Cutaneous follicle center lymphoma also may present as 1 or more localized erythematous papules, plaques, and/or nodules, commonly arising on the scalp/forehead or trunk of middle-aged men. Despite being a low-grade lymphoma with a favorable prognosis, it may have a relatively fast growth and locally aggressive course if left untreated. The distinguishing histologic feature is a dense proliferation of neoplastic infiltrates in the dermis, which is separated from the epidermis by the grenz zone.⁶ 

The clinical presentation of cutaneous metastatic carcinomas varies greatly, with 1 or multiple localized or widespread lesions commonly involving the abdominal wall, scalp, and face. The lesions also may mimic benign dermatologic conditions, thus potentially resulting in erroneous clinical diagnosis and delayed therapy of the primary malignancy. Obtaining clinical history is crucial; however, a precise diagnosis may require histologic examination.⁷ 

Atypical fibroxanthoma is a rare superficial cutaneous sarcoma that typically occurs on the head and neck in sun-damaged elderly individuals. Clinically, AFX presents as well-circumscribed red or pink nodules or plaques with or without ulceration, crust, or scale.⁸ Atypical fibroxanthoma lesions usually are small, with a median diameter of 1 cm, while those greater than 2 cm reportedly account for less than 5% of cases.⁹ Atypical fibroxanthoma typically grows rapidly with no pain or discomfort. Histologically, AFX is characterized by a well-circumscribed dermal nodule consisting of pleomorphic spindle cells and multinucleated giant cells that can stain positively for CD10 and procollagen 1.¹⁰ 

Cutaneous pseudolymphoma is a benign inflammatory response process that stimulates polyclonal T- or B-cell lymphoproliferation. The clinical presentation may appear as localized or disseminated flesh-colored or red papules, infiltrated plaques, and nodules.¹¹ Histopathology will show mixtures of B and T cells along with dendritic cells and macrophages, but irregular vascular structure and dissecting dermal collagen are not involved. 

We present an unusual case of CAS with multiple pink nodules on the scalp. Early biopsy of these lesions is important to reach a correct diagnosis and to initiate appropriate treatment. 

The Diagnosis: Cutaneous Angiosarcoma 

Biopsy revealed a cellular neoplasm consisting of atypical polygonal cells with a hobnailed appearance, vasoformative characteristics, and rare extravasated erythrocytes. The tumor had an infiltrative growth pattern as demonstrated by dissecting dermal collagen and a poorly defined border with adjacent normal tissue (Figure 1). Immunohistochemistry revealed that the lesion was positive for CD31 and D2-40 (Figure 2) but negative for cytokeratin, CD10, CD68, human herpesvirus 8, CD34, and Melan A, thus confirming the endothelial origin of the tumor cells and the diagnosis of cutaneous angiosarcoma (CAS). The patient was treated with extended surgical excision and radiation therapy. No recurrence or metastasis was found throughout 2 years of follow-up.  

Radical resection with a negative margin is considered the first-line treatment of choice. Although there is a paucity of studies assessing the specific width of surgical margins, application of no less than a 3-cm peripheral margin as well as a clear deep margin is recommended.⁵ Adjuvant radiation therapy also is essential to prevent local recurrence. Patients receiving combination therapy have a superior overall survival rate when compared to those undergoing surgery or radiation therapy alone.⁴  

Cutaneous follicle center lymphoma also may present as 1 or more localized erythematous papules, plaques, and/or nodules, commonly arising on the scalp/forehead or trunk of middle-aged men. Despite being a low-grade lymphoma with a favorable prognosis, it may have a relatively fast growth and locally aggressive course if left untreated. The distinguishing histologic feature is a dense proliferation of neoplastic infiltrates in the dermis, which is separated from the epidermis by the grenz zone.⁶ 

The clinical presentation of cutaneous metastatic carcinomas varies greatly, with 1 or multiple localized or widespread lesions commonly involving the abdominal wall, scalp, and face. The lesions also may mimic benign dermatologic conditions, thus potentially resulting in erroneous clinical diagnosis and delayed therapy of the primary malignancy. Obtaining clinical history is crucial; however, a precise diagnosis may require histologic examination.⁷ 

Atypical fibroxanthoma is a rare superficial cutaneous sarcoma that typically occurs on the head and neck in sun-damaged elderly individuals. Clinically, AFX presents as well-circumscribed red or pink nodules or plaques with or without ulceration, crust, or scale.⁸ Atypical fibroxanthoma lesions usually are small, with a median diameter of 1 cm, while those greater than 2 cm reportedly account for less than 5% of cases.⁹ Atypical fibroxanthoma typically grows rapidly with no pain or discomfort. Histologically, AFX is characterized by a well-circumscribed dermal nodule consisting of pleomorphic spindle cells and multinucleated giant cells that can stain positively for CD10 and procollagen 1.¹⁰ 

Cutaneous pseudolymphoma is a benign inflammatory response process that stimulates polyclonal T- or B-cell lymphoproliferation. The clinical presentation may appear as localized or disseminated flesh-colored or red papules, infiltrated plaques, and nodules.¹¹ Histopathology will show mixtures of B and T cells along with dendritic cells and macrophages, but irregular vascular structure and dissecting dermal collagen are not involved. 

We present an unusual case of CAS with multiple pink nodules on the scalp. Early biopsy of these lesions is important to reach a correct diagnosis and to initiate appropriate treatment. 

The Diagnosis: Cutaneous Angiosarcoma 

Biopsy revealed a cellular neoplasm consisting of atypical polygonal cells with a hobnailed appearance, vasoformative characteristics, and rare extravasated erythrocytes. The tumor had an infiltrative growth pattern as demonstrated by dissecting dermal collagen and a poorly defined border with adjacent normal tissue (Figure 1). Immunohistochemistry revealed that the lesion was positive for CD31 and D2-40 (Figure 2) but negative for cytokeratin, CD10, CD68, human herpesvirus 8, CD34, and Melan A, thus confirming the endothelial origin of the tumor cells and the diagnosis of cutaneous angiosarcoma (CAS). The patient was treated with extended surgical excision and radiation therapy. No recurrence or metastasis was found throughout 2 years of follow-up.  

Radical resection with a negative margin is considered the first-line treatment of choice. Although there is a paucity of studies assessing the specific width of surgical margins, application of no less than a 3-cm peripheral margin as well as a clear deep margin is recommended.⁵ Adjuvant radiation therapy also is essential to prevent local recurrence. Patients receiving combination therapy have a superior overall survival rate when compared to those undergoing surgery or radiation therapy alone.⁴  

Cutaneous follicle center lymphoma also may present as 1 or more localized erythematous papules, plaques, and/or nodules, commonly arising on the scalp/forehead or trunk of middle-aged men. Despite being a low-grade lymphoma with a favorable prognosis, it may have a relatively fast growth and locally aggressive course if left untreated. The distinguishing histologic feature is a dense proliferation of neoplastic infiltrates in the dermis, which is separated from the epidermis by the grenz zone.⁶ 

The clinical presentation of cutaneous metastatic carcinomas varies greatly, with 1 or multiple localized or widespread lesions commonly involving the abdominal wall, scalp, and face. The lesions also may mimic benign dermatologic conditions, thus potentially resulting in erroneous clinical diagnosis and delayed therapy of the primary malignancy. Obtaining clinical history is crucial; however, a precise diagnosis may require histologic examination.⁷ 

Atypical fibroxanthoma is a rare superficial cutaneous sarcoma that typically occurs on the head and neck in sun-damaged elderly individuals. Clinically, AFX presents as well-circumscribed red or pink nodules or plaques with or without ulceration, crust, or scale.⁸ Atypical fibroxanthoma lesions usually are small, with a median diameter of 1 cm, while those greater than 2 cm reportedly account for less than 5% of cases.⁹ Atypical fibroxanthoma typically grows rapidly with no pain or discomfort. Histologically, AFX is characterized by a well-circumscribed dermal nodule consisting of pleomorphic spindle cells and multinucleated giant cells that can stain positively for CD10 and procollagen 1.¹⁰ 

Cutaneous pseudolymphoma is a benign inflammatory response process that stimulates polyclonal T- or B-cell lymphoproliferation. The clinical presentation may appear as localized or disseminated flesh-colored or red papules, infiltrated plaques, and nodules.¹¹ Histopathology will show mixtures of B and T cells along with dendritic cells and macrophages, but irregular vascular structure and dissecting dermal collagen are not involved. 

We present an unusual case of CAS with multiple pink nodules on the scalp. Early biopsy of these lesions is important to reach a correct diagnosis and to initiate appropriate treatment. 

Congenital onychodysplasia of the index finger (COIF), or Iso-Kikuchi syndrome, is a rare disorder characterized by malformation of one or both nails of the index fingers. The various anomalies described are anonychia, micronychia, polyonychia, malalignment, or hemi-onychogryphosis. It may be associated with abnormalities of the underlying phalangeal bone, the most masked being bifurcation of the terminal phalange.¹ Initially thought to be nonhereditary and nonfamilial,² it is now known that COIF can be inherited in an autosomal-dominant fashion.³ Millman and Strier³ described a family of 9 patients with COIF. It rarely is described outside of Japan. Padmavathy et al⁴ described a case in an Indian patient with COIF that was associated with the absence of a ring finger in addition to anomalies of the metacarpal bones.

Congenital onychodysplasia of the index finger has a broad spectrum regarding its etiology and clinical features.⁵ The pathogenesis of COIF still is poorly understood. Deficient circulation in digital arteries is thought to be a putative mechanism for developing a deformed nail. The nail is affected on the radial side of the index finger, likely because of the smaller caliber of the artery on that side.⁵ Hereditary as well as nonhereditary sporadic cases have been reported. In addition to the various fingernail anomalies, skeletal abnormalities also have been reported. Baran and Stroud⁶ have reported deformed lunulae as a manifestation of COIF.

The Diagnosis: Congenital Onychodysplasia of the Index Finger

The differential diagnosis of COIF includes hidrotic ectodermal dysplasia, nail-patella syndrome, Poland syndrome, and DOOR syndrome. Hidrotic ectodermal dysplasia exhibits onychodystrophy, generalized hypotrichosis, palmoplantar keratoderma, and dental anomalies.⁷ Nail-patella syndrome presents with hypoplasia of the fingernails and toenails, triangular nail lunulae, absent or hypoplastic patellae, and elbow and iliac horn dysplasia. Poland syndrome is distinguished from COIF by the congenital absence of the pectoralis major muscle on the ipsilateral side of the involved digits. The DOOR syndrome tetrad is comprised of deafness, onychodystrophy, osteodystrophy, and mental retardation.⁸ Unlike these conditions, COIF does not involve systems other than the nails and phalanges.

Treatment of this condition is mainly conservative, as patients typically do not have symptoms.⁹ Surgical interventions can be considered for cosmetic concerns. Knowledge of this congenital entity and its clinical findings is essential to prevent unnecessary procedures and workup.

Congenital onychodysplasia of the index finger (COIF), or Iso-Kikuchi syndrome, is a rare disorder characterized by malformation of one or both nails of the index fingers. The various anomalies described are anonychia, micronychia, polyonychia, malalignment, or hemi-onychogryphosis. It may be associated with abnormalities of the underlying phalangeal bone, the most masked being bifurcation of the terminal phalange.¹ Initially thought to be nonhereditary and nonfamilial,² it is now known that COIF can be inherited in an autosomal-dominant fashion.³ Millman and Strier³ described a family of 9 patients with COIF. It rarely is described outside of Japan. Padmavathy et al⁴ described a case in an Indian patient with COIF that was associated with the absence of a ring finger in addition to anomalies of the metacarpal bones.

Congenital onychodysplasia of the index finger has a broad spectrum regarding its etiology and clinical features.⁵ The pathogenesis of COIF still is poorly understood. Deficient circulation in digital arteries is thought to be a putative mechanism for developing a deformed nail. The nail is affected on the radial side of the index finger, likely because of the smaller caliber of the artery on that side.⁵ Hereditary as well as nonhereditary sporadic cases have been reported. In addition to the various fingernail anomalies, skeletal abnormalities also have been reported. Baran and Stroud⁶ have reported deformed lunulae as a manifestation of COIF.

The Diagnosis: Congenital Onychodysplasia of the Index Finger

The differential diagnosis of COIF includes hidrotic ectodermal dysplasia, nail-patella syndrome, Poland syndrome, and DOOR syndrome. Hidrotic ectodermal dysplasia exhibits onychodystrophy, generalized hypotrichosis, palmoplantar keratoderma, and dental anomalies.⁷ Nail-patella syndrome presents with hypoplasia of the fingernails and toenails, triangular nail lunulae, absent or hypoplastic patellae, and elbow and iliac horn dysplasia. Poland syndrome is distinguished from COIF by the congenital absence of the pectoralis major muscle on the ipsilateral side of the involved digits. The DOOR syndrome tetrad is comprised of deafness, onychodystrophy, osteodystrophy, and mental retardation.⁸ Unlike these conditions, COIF does not involve systems other than the nails and phalanges.

Treatment of this condition is mainly conservative, as patients typically do not have symptoms.⁹ Surgical interventions can be considered for cosmetic concerns. Knowledge of this congenital entity and its clinical findings is essential to prevent unnecessary procedures and workup.

Congenital onychodysplasia of the index finger (COIF), or Iso-Kikuchi syndrome, is a rare disorder characterized by malformation of one or both nails of the index fingers. The various anomalies described are anonychia, micronychia, polyonychia, malalignment, or hemi-onychogryphosis. It may be associated with abnormalities of the underlying phalangeal bone, the most masked being bifurcation of the terminal phalange.¹ Initially thought to be nonhereditary and nonfamilial,² it is now known that COIF can be inherited in an autosomal-dominant fashion.³ Millman and Strier³ described a family of 9 patients with COIF. It rarely is described outside of Japan. Padmavathy et al⁴ described a case in an Indian patient with COIF that was associated with the absence of a ring finger in addition to anomalies of the metacarpal bones.

Congenital onychodysplasia of the index finger has a broad spectrum regarding its etiology and clinical features.⁵ The pathogenesis of COIF still is poorly understood. Deficient circulation in digital arteries is thought to be a putative mechanism for developing a deformed nail. The nail is affected on the radial side of the index finger, likely because of the smaller caliber of the artery on that side.⁵ Hereditary as well as nonhereditary sporadic cases have been reported. In addition to the various fingernail anomalies, skeletal abnormalities also have been reported. Baran and Stroud⁶ have reported deformed lunulae as a manifestation of COIF.

The Diagnosis: Congenital Onychodysplasia of the Index Finger

The differential diagnosis of COIF includes hidrotic ectodermal dysplasia, nail-patella syndrome, Poland syndrome, and DOOR syndrome. Hidrotic ectodermal dysplasia exhibits onychodystrophy, generalized hypotrichosis, palmoplantar keratoderma, and dental anomalies.⁷ Nail-patella syndrome presents with hypoplasia of the fingernails and toenails, triangular nail lunulae, absent or hypoplastic patellae, and elbow and iliac horn dysplasia. Poland syndrome is distinguished from COIF by the congenital absence of the pectoralis major muscle on the ipsilateral side of the involved digits. The DOOR syndrome tetrad is comprised of deafness, onychodystrophy, osteodystrophy, and mental retardation.⁸ Unlike these conditions, COIF does not involve systems other than the nails and phalanges.

Treatment of this condition is mainly conservative, as patients typically do not have symptoms.⁹ Surgical interventions can be considered for cosmetic concerns. Knowledge of this congenital entity and its clinical findings is essential to prevent unnecessary procedures and workup.

The Diagnosis: Dowling-Degos Disease

Histopathology demonstrated elongation of the epidermal rete ridges with increased basal pigmentation, suprapapillary epithelial thinning, dermal melanophages, and a mild lymphocytic infiltrate (Figure). Given the clinical and histologic findings, a diagnosis of Dowling-Degos disease (DDD) was made. The patient was counseled on the increased risk for her children developing DDD. Treatment with the erbium:YAG (Er:YAG) laser subsequently was initiated.

Dowling-Degos disease (also known as reticulate pigmented anomaly of the flexures) is an uncommon autosomal-dominant condition characterized by reticular hyperpigmentation involving the flexural and intertriginous sites. Classic DDD commonly is caused by lossof-function mutations in the keratin 5 gene, KRT5¹; however, DDD also may result from loss-of-function mutations in the protein O-fucosyltransferase 1, POFUT1, and protein O-glucosyltransferase 1, POGLUT1, genes.²

Rare cases of DDD associated with hidradenitis suppurativa are caused by mutations in the presenilin enhancer protein 2 gene, PSENEN.³

Of note, a missense mutation in KRT5 is implicated in epidermolysis bullosa simplex with mottled pigmentation. Onset of DDD typically occurs during the third to fourth decades of life. Reticulated hyperpigmented macules initially occur in the axillae and groin and progressively increase over time to involve the neck, inframammary folds, trunk, and flexural surfaces of the arms and thighs. Patients additionally may present with pitted perioral scars, comedolike lesions on the back and neck, epidermoid cysts, and hidradenitis suppurativa. Keratoacanthoma and squamous cell carcinoma rarely have been reported in association with classic DDD.^4,5

Dowling-Degos disease usually is asymptomatic, though pruritus seldom may occur in the affected flexural areas. Histologically, the epidermal rete ridges are elongated in a filiform or antlerlike pattern with increased pigmentation of the basal layer and thinning of the suprapapillary epithelium. Dermal melanosis and a mild perivascular lymphohistiocytic infiltrate also are present with no increase in the number of melanocytes.^6,7 Galli-Galli disease is a variant of DDD that shares similar clinical and histologic features of DDD but is distinguished from DDD by suprabasilar nondyskeratotic acantholysis on histology.⁸

Regarding other differential diagnoses for our patient, acanthosis nigricans may be distinguished clinically by the presence of velvety and/or verrucous plaques, commonly in the neck folds and axillae. Histologically, acanthosis nigricans is distinct from DDD and involves hyperkeratosis, acanthosis, and epidermal papillomatosis. Our patient had no history of diabetes mellitus or insulin resistance. Granular parakeratosis presents with hyperpigmented hyperkeratotic papules and plaques classically confined to the axillary region; however, the involvement of other intertriginous areas may occur. Histologically, granular parakeratosis demonstrates compact parakeratosis with small bluish keratohyalin granules within the stratum corneum. Confluent and reticulated papillomatosis presents with red-brown keratotic papules that initially appear in the intermammary region and spread laterally forming a reticulated pattern. Histology is similar to acanthosis nigricans and demonstrates hyperkeratosis, acanthosis, and papillomatosis. Inverse psoriasis presents with symmetric and sharply demarcated, erythematous, nonscaly plaques in the intertriginous areas. The plaques of inverse psoriasis may be pruritic and/or sore and occasionally may become macerated. Inverse psoriasis shares similar histologic findings compared to classic plaque psoriasis but may have less confluent parakeratosis.

Treatment of DDD essentially is reserved for cosmetic reasons. Topical hydroquinone, tretinoin, and corticosteroids have been used with limited to no success.^5,9 Beneficial results after treatment with the Er:YAG laser have been reported.¹⁰

The Diagnosis: Dowling-Degos Disease

Histopathology demonstrated elongation of the epidermal rete ridges with increased basal pigmentation, suprapapillary epithelial thinning, dermal melanophages, and a mild lymphocytic infiltrate (Figure). Given the clinical and histologic findings, a diagnosis of Dowling-Degos disease (DDD) was made. The patient was counseled on the increased risk for her children developing DDD. Treatment with the erbium:YAG (Er:YAG) laser subsequently was initiated.

Dowling-Degos disease (also known as reticulate pigmented anomaly of the flexures) is an uncommon autosomal-dominant condition characterized by reticular hyperpigmentation involving the flexural and intertriginous sites. Classic DDD commonly is caused by lossof-function mutations in the keratin 5 gene, KRT5¹; however, DDD also may result from loss-of-function mutations in the protein O-fucosyltransferase 1, POFUT1, and protein O-glucosyltransferase 1, POGLUT1, genes.²

Rare cases of DDD associated with hidradenitis suppurativa are caused by mutations in the presenilin enhancer protein 2 gene, PSENEN.³

Of note, a missense mutation in KRT5 is implicated in epidermolysis bullosa simplex with mottled pigmentation. Onset of DDD typically occurs during the third to fourth decades of life. Reticulated hyperpigmented macules initially occur in the axillae and groin and progressively increase over time to involve the neck, inframammary folds, trunk, and flexural surfaces of the arms and thighs. Patients additionally may present with pitted perioral scars, comedolike lesions on the back and neck, epidermoid cysts, and hidradenitis suppurativa. Keratoacanthoma and squamous cell carcinoma rarely have been reported in association with classic DDD.^4,5

Dowling-Degos disease usually is asymptomatic, though pruritus seldom may occur in the affected flexural areas. Histologically, the epidermal rete ridges are elongated in a filiform or antlerlike pattern with increased pigmentation of the basal layer and thinning of the suprapapillary epithelium. Dermal melanosis and a mild perivascular lymphohistiocytic infiltrate also are present with no increase in the number of melanocytes.^6,7 Galli-Galli disease is a variant of DDD that shares similar clinical and histologic features of DDD but is distinguished from DDD by suprabasilar nondyskeratotic acantholysis on histology.⁸

Regarding other differential diagnoses for our patient, acanthosis nigricans may be distinguished clinically by the presence of velvety and/or verrucous plaques, commonly in the neck folds and axillae. Histologically, acanthosis nigricans is distinct from DDD and involves hyperkeratosis, acanthosis, and epidermal papillomatosis. Our patient had no history of diabetes mellitus or insulin resistance. Granular parakeratosis presents with hyperpigmented hyperkeratotic papules and plaques classically confined to the axillary region; however, the involvement of other intertriginous areas may occur. Histologically, granular parakeratosis demonstrates compact parakeratosis with small bluish keratohyalin granules within the stratum corneum. Confluent and reticulated papillomatosis presents with red-brown keratotic papules that initially appear in the intermammary region and spread laterally forming a reticulated pattern. Histology is similar to acanthosis nigricans and demonstrates hyperkeratosis, acanthosis, and papillomatosis. Inverse psoriasis presents with symmetric and sharply demarcated, erythematous, nonscaly plaques in the intertriginous areas. The plaques of inverse psoriasis may be pruritic and/or sore and occasionally may become macerated. Inverse psoriasis shares similar histologic findings compared to classic plaque psoriasis but may have less confluent parakeratosis.

Treatment of DDD essentially is reserved for cosmetic reasons. Topical hydroquinone, tretinoin, and corticosteroids have been used with limited to no success.^5,9 Beneficial results after treatment with the Er:YAG laser have been reported.¹⁰

The Diagnosis: Dowling-Degos Disease

Histopathology demonstrated elongation of the epidermal rete ridges with increased basal pigmentation, suprapapillary epithelial thinning, dermal melanophages, and a mild lymphocytic infiltrate (Figure). Given the clinical and histologic findings, a diagnosis of Dowling-Degos disease (DDD) was made. The patient was counseled on the increased risk for her children developing DDD. Treatment with the erbium:YAG (Er:YAG) laser subsequently was initiated.

Dowling-Degos disease (also known as reticulate pigmented anomaly of the flexures) is an uncommon autosomal-dominant condition characterized by reticular hyperpigmentation involving the flexural and intertriginous sites. Classic DDD commonly is caused by lossof-function mutations in the keratin 5 gene, KRT5¹; however, DDD also may result from loss-of-function mutations in the protein O-fucosyltransferase 1, POFUT1, and protein O-glucosyltransferase 1, POGLUT1, genes.²

Rare cases of DDD associated with hidradenitis suppurativa are caused by mutations in the presenilin enhancer protein 2 gene, PSENEN.³

Of note, a missense mutation in KRT5 is implicated in epidermolysis bullosa simplex with mottled pigmentation. Onset of DDD typically occurs during the third to fourth decades of life. Reticulated hyperpigmented macules initially occur in the axillae and groin and progressively increase over time to involve the neck, inframammary folds, trunk, and flexural surfaces of the arms and thighs. Patients additionally may present with pitted perioral scars, comedolike lesions on the back and neck, epidermoid cysts, and hidradenitis suppurativa. Keratoacanthoma and squamous cell carcinoma rarely have been reported in association with classic DDD.^4,5

Dowling-Degos disease usually is asymptomatic, though pruritus seldom may occur in the affected flexural areas. Histologically, the epidermal rete ridges are elongated in a filiform or antlerlike pattern with increased pigmentation of the basal layer and thinning of the suprapapillary epithelium. Dermal melanosis and a mild perivascular lymphohistiocytic infiltrate also are present with no increase in the number of melanocytes.^6,7 Galli-Galli disease is a variant of DDD that shares similar clinical and histologic features of DDD but is distinguished from DDD by suprabasilar nondyskeratotic acantholysis on histology.⁸

Regarding other differential diagnoses for our patient, acanthosis nigricans may be distinguished clinically by the presence of velvety and/or verrucous plaques, commonly in the neck folds and axillae. Histologically, acanthosis nigricans is distinct from DDD and involves hyperkeratosis, acanthosis, and epidermal papillomatosis. Our patient had no history of diabetes mellitus or insulin resistance. Granular parakeratosis presents with hyperpigmented hyperkeratotic papules and plaques classically confined to the axillary region; however, the involvement of other intertriginous areas may occur. Histologically, granular parakeratosis demonstrates compact parakeratosis with small bluish keratohyalin granules within the stratum corneum. Confluent and reticulated papillomatosis presents with red-brown keratotic papules that initially appear in the intermammary region and spread laterally forming a reticulated pattern. Histology is similar to acanthosis nigricans and demonstrates hyperkeratosis, acanthosis, and papillomatosis. Inverse psoriasis presents with symmetric and sharply demarcated, erythematous, nonscaly plaques in the intertriginous areas. The plaques of inverse psoriasis may be pruritic and/or sore and occasionally may become macerated. Inverse psoriasis shares similar histologic findings compared to classic plaque psoriasis but may have less confluent parakeratosis.

Treatment of DDD essentially is reserved for cosmetic reasons. Topical hydroquinone, tretinoin, and corticosteroids have been used with limited to no success.^5,9 Beneficial results after treatment with the Er:YAG laser have been reported.¹⁰

The Diagnosis: Platelike Osteoma Cutis 

Histopathologic examination revealed extensive cutaneous ossification in the dermis and subcutis with dermal fibrosis and minimal surrounding inflammation (Figure 1). There was no evidence of infection or neoplasm. Further evaluation did not demonstrate any additional physical dysmorphia, and there were no imbalances of calcium-phosphate metabolism or abnormalities in parathyroid hormone or thyroid hormone function. A diagnosis of platelike osteoma cutis (PLOC) was favored. Computed tomography of the head showed material at the posterior skull of similar density to the adjacent calvarial skull and centered within the dermis, consistent with osteoma cutis (Figure 2). 

Osteoma cutis describes the formation of bone within the skin. It occurs when hydroxyapatite crystals in a proteinaceous matrix are deposited within the skin, ultimately leading to the formation of bone ultrastructure. Ossification of the skin most often occurs secondary to trauma, inflammation, or neoplasm; however, it rarely may be a primary event.^1,2 

Platelike osteoma cutis is a rare form of primary cutaneous ossification in which bone forms within the skin in a platelike manner. It most frequently affects the scalp but also has been observed on the trunk and extremities.¹ A driving metabolic or endocrine abnormality typically is not identified.² 

Platelike osteoma cutis can occur as an isolated finding or as a feature of Albright hereditary osteodystrophy (AHO) or progressive osseous heteroplasia (POH). In addition to cutaneous ossification, AHO involves short stature, endocrinopathy, obesity, shortened fourth and fifth metacarpals, and mental retardation. Progressive osseous heteroplasia is characterized by progressive ossification of the skin and deeper tissues such as muscle and fascia, leading to severe movement restriction; it is believed to be a localized nonprogressive variant of POH.^3,4 Mutations in the guanine nucleotide binding protein, alpha stimulating activity polypeptide 1 gene, GNAS1, a key regulatory gene involved in AHO and POH, have been found in several cases of PLOC.³ Our patient lacked any dysmorphic features or laboratory abnormalities suggestive of AHO or POH. Moreover, testing of the tissue and blood for the GNAS1 mutation was negative. Treatment of PLOC often is difficult. Our patient underwent a trial of ablative fractional laser resurfacing, which failed to lead to perceivable improvement.  

The differential diagnoses include a kerion, dissecting cellulitis of the scalp, folliculitis decalvans, and acne keloidalis nuchae. A kerion is a manifestation of tinea capitis characterized by an inflammatory plaque, often with pain or tenderness. Kerions most frequently occur in children aged 5 to 10 years.⁵ Failure to treat a kerion may result in scarring alopecia. Treatment consists of oral antifungals.  

Dissecting cellulitis of the scalp is thought to occur secondary to follicular occlusion. It is characterized by boggy suppurative nodules primarily on the posterior and vertex scalp. Patchy hair loss is present and typically progresses to cicatricial alopecia. Histology characteristically shows areas of dense, predominantly neutrophilic, perifollicular dermal infiltrates.⁶ 

Folliculitis decalvans is a primary neutrophilic cicatricial alopecia that primarily occurs in adults. Patients with folliculitis decalvans tend to have multiple pustules on the periphery of confluent areas of scarring alopecia. It is theorized that an immune response to staphylococcal superantigens contributes to this disease process.⁷  

The clinical findings of acne keloidalis nuchae include inflammatory pustules and papules with keloidlike plaques on the posterior neck and scalp. It occurs predominantly in teenaged and adult males of African ancestry.⁸ Treatment is aimed at reducing inflammation and preventing exacerbating factors. Severe disease courses may lead to scarring alopecia.

The Diagnosis: Platelike Osteoma Cutis 

Histopathologic examination revealed extensive cutaneous ossification in the dermis and subcutis with dermal fibrosis and minimal surrounding inflammation (Figure 1). There was no evidence of infection or neoplasm. Further evaluation did not demonstrate any additional physical dysmorphia, and there were no imbalances of calcium-phosphate metabolism or abnormalities in parathyroid hormone or thyroid hormone function. A diagnosis of platelike osteoma cutis (PLOC) was favored. Computed tomography of the head showed material at the posterior skull of similar density to the adjacent calvarial skull and centered within the dermis, consistent with osteoma cutis (Figure 2). 

Osteoma cutis describes the formation of bone within the skin. It occurs when hydroxyapatite crystals in a proteinaceous matrix are deposited within the skin, ultimately leading to the formation of bone ultrastructure. Ossification of the skin most often occurs secondary to trauma, inflammation, or neoplasm; however, it rarely may be a primary event.^1,2 

Platelike osteoma cutis is a rare form of primary cutaneous ossification in which bone forms within the skin in a platelike manner. It most frequently affects the scalp but also has been observed on the trunk and extremities.¹ A driving metabolic or endocrine abnormality typically is not identified.² 

Platelike osteoma cutis can occur as an isolated finding or as a feature of Albright hereditary osteodystrophy (AHO) or progressive osseous heteroplasia (POH). In addition to cutaneous ossification, AHO involves short stature, endocrinopathy, obesity, shortened fourth and fifth metacarpals, and mental retardation. Progressive osseous heteroplasia is characterized by progressive ossification of the skin and deeper tissues such as muscle and fascia, leading to severe movement restriction; it is believed to be a localized nonprogressive variant of POH.^3,4 Mutations in the guanine nucleotide binding protein, alpha stimulating activity polypeptide 1 gene, GNAS1, a key regulatory gene involved in AHO and POH, have been found in several cases of PLOC.³ Our patient lacked any dysmorphic features or laboratory abnormalities suggestive of AHO or POH. Moreover, testing of the tissue and blood for the GNAS1 mutation was negative. Treatment of PLOC often is difficult. Our patient underwent a trial of ablative fractional laser resurfacing, which failed to lead to perceivable improvement.  

The differential diagnoses include a kerion, dissecting cellulitis of the scalp, folliculitis decalvans, and acne keloidalis nuchae. A kerion is a manifestation of tinea capitis characterized by an inflammatory plaque, often with pain or tenderness. Kerions most frequently occur in children aged 5 to 10 years.⁵ Failure to treat a kerion may result in scarring alopecia. Treatment consists of oral antifungals.  

Dissecting cellulitis of the scalp is thought to occur secondary to follicular occlusion. It is characterized by boggy suppurative nodules primarily on the posterior and vertex scalp. Patchy hair loss is present and typically progresses to cicatricial alopecia. Histology characteristically shows areas of dense, predominantly neutrophilic, perifollicular dermal infiltrates.⁶ 

Folliculitis decalvans is a primary neutrophilic cicatricial alopecia that primarily occurs in adults. Patients with folliculitis decalvans tend to have multiple pustules on the periphery of confluent areas of scarring alopecia. It is theorized that an immune response to staphylococcal superantigens contributes to this disease process.⁷  

The clinical findings of acne keloidalis nuchae include inflammatory pustules and papules with keloidlike plaques on the posterior neck and scalp. It occurs predominantly in teenaged and adult males of African ancestry.⁸ Treatment is aimed at reducing inflammation and preventing exacerbating factors. Severe disease courses may lead to scarring alopecia.

The Diagnosis: Platelike Osteoma Cutis 

Histopathologic examination revealed extensive cutaneous ossification in the dermis and subcutis with dermal fibrosis and minimal surrounding inflammation (Figure 1). There was no evidence of infection or neoplasm. Further evaluation did not demonstrate any additional physical dysmorphia, and there were no imbalances of calcium-phosphate metabolism or abnormalities in parathyroid hormone or thyroid hormone function. A diagnosis of platelike osteoma cutis (PLOC) was favored. Computed tomography of the head showed material at the posterior skull of similar density to the adjacent calvarial skull and centered within the dermis, consistent with osteoma cutis (Figure 2). 

Osteoma cutis describes the formation of bone within the skin. It occurs when hydroxyapatite crystals in a proteinaceous matrix are deposited within the skin, ultimately leading to the formation of bone ultrastructure. Ossification of the skin most often occurs secondary to trauma, inflammation, or neoplasm; however, it rarely may be a primary event.^1,2 

Platelike osteoma cutis is a rare form of primary cutaneous ossification in which bone forms within the skin in a platelike manner. It most frequently affects the scalp but also has been observed on the trunk and extremities.¹ A driving metabolic or endocrine abnormality typically is not identified.² 

Platelike osteoma cutis can occur as an isolated finding or as a feature of Albright hereditary osteodystrophy (AHO) or progressive osseous heteroplasia (POH). In addition to cutaneous ossification, AHO involves short stature, endocrinopathy, obesity, shortened fourth and fifth metacarpals, and mental retardation. Progressive osseous heteroplasia is characterized by progressive ossification of the skin and deeper tissues such as muscle and fascia, leading to severe movement restriction; it is believed to be a localized nonprogressive variant of POH.^3,4 Mutations in the guanine nucleotide binding protein, alpha stimulating activity polypeptide 1 gene, GNAS1, a key regulatory gene involved in AHO and POH, have been found in several cases of PLOC.³ Our patient lacked any dysmorphic features or laboratory abnormalities suggestive of AHO or POH. Moreover, testing of the tissue and blood for the GNAS1 mutation was negative. Treatment of PLOC often is difficult. Our patient underwent a trial of ablative fractional laser resurfacing, which failed to lead to perceivable improvement.  

The differential diagnoses include a kerion, dissecting cellulitis of the scalp, folliculitis decalvans, and acne keloidalis nuchae. A kerion is a manifestation of tinea capitis characterized by an inflammatory plaque, often with pain or tenderness. Kerions most frequently occur in children aged 5 to 10 years.⁵ Failure to treat a kerion may result in scarring alopecia. Treatment consists of oral antifungals.  

Dissecting cellulitis of the scalp is thought to occur secondary to follicular occlusion. It is characterized by boggy suppurative nodules primarily on the posterior and vertex scalp. Patchy hair loss is present and typically progresses to cicatricial alopecia. Histology characteristically shows areas of dense, predominantly neutrophilic, perifollicular dermal infiltrates.⁶ 

Folliculitis decalvans is a primary neutrophilic cicatricial alopecia that primarily occurs in adults. Patients with folliculitis decalvans tend to have multiple pustules on the periphery of confluent areas of scarring alopecia. It is theorized that an immune response to staphylococcal superantigens contributes to this disease process.⁷  

The clinical findings of acne keloidalis nuchae include inflammatory pustules and papules with keloidlike plaques on the posterior neck and scalp. It occurs predominantly in teenaged and adult males of African ancestry.⁸ Treatment is aimed at reducing inflammation and preventing exacerbating factors. Severe disease courses may lead to scarring alopecia.

The Diagnosis: Paraneoplastic Acanthosis Nigricans 

Histopathologic examination demonstrated verrucous epidermal hyperplasia (Figure, A). Fungal organisms were identified with an Alcian blue and periodic acid-Schiff stain (Figure, B). The organisms demonstrated a vertical orientation in relation to the mucosal surface, which was consistent with candidal organisms.  

Given the rapid eruption of these plaques, the distribution on the oral and palmar surfaces (tripe palms), and the minimal improvement with both systemic steroids and antifungal treatment, a diagnosis of paraneoplastic acanthosis nigricans with secondary candidal infection was made. Drug-induced cheilitis was considered; however, improvement with discontinuation of the suspected offending drug would have been expected. Although chronic mucocutaneous candidiasis was possible, more prompt improvement upon initiation of systemic antifungal therapy would have been observed. Oral Crohn disease should be included in the differential, but it was unlikely given the lack of granulomas on pathology and absence of history of gastrointestinal tract symptoms. Melkersson-Rosenthal syndrome also was unlikely given the lack of facial nerve palsy as well as the lack of granulomas on pathology. Furthermore, none of these options would be associated with tripe palms, as seen in our patient.  

Acanthosis nigricans is a localized skin disorder characterized by hyperpigmented velvety plaques arising in flexural and intertriginous regions. Although most cases (80%) are associated with idiopathic or benign conditions, the link between acanthosis nigricans and an underlying malignancy has been well documented.^1-3 Most commonly associated with an underlying intra-abdominal malignancy (often gastric carcinoma), the lesions of paraneoplastic acanthosis nigricans are indistinguishable from their benign counterparts^.1,4 When the condition presents abruptly and extensively in a nonobese patient, prompt workup for malignancy should be initiated. Rapid onset and atypical distribution (ie, palmar, perioral, or mucosal) more commonly is associated with a paraneoplastic etiology.^5,6 

Histopathology for acanthosis nigricans shows hyperkeratosis and epidermal papillomatosis. Horn pseudocyst formation is possible, but usually no hyperpigmentation is observed. The findings typically are indistinguishable from seborrheic keratoses, epidermal nevi, or lesions of confluent and reticulated papillomatosis of Gougerot and Carteaud.² 

The underlying pathogenesis of acanthosis nigricans is poorly understood. In the benign subtype, insulin resistance commonly has been described. In the paraneoplastic subtype, it is proposed that the tumor produces a transforming growth factor that mimics epidermal growth factor and leads to keratinocyte proliferation.^7,8 Paraneoplastic acanthosis nigricans has the potential to arise at any point of tumor development, further contributing to the diagnostic challenge. Treatment of the skin lesions involves management of the underlying malignancy. Unfortunately, many such malignancies often are at an advanced stage, and subsequent prognosis is poor.² 

The Diagnosis: Paraneoplastic Acanthosis Nigricans 

Histopathologic examination demonstrated verrucous epidermal hyperplasia (Figure, A). Fungal organisms were identified with an Alcian blue and periodic acid-Schiff stain (Figure, B). The organisms demonstrated a vertical orientation in relation to the mucosal surface, which was consistent with candidal organisms.  

Given the rapid eruption of these plaques, the distribution on the oral and palmar surfaces (tripe palms), and the minimal improvement with both systemic steroids and antifungal treatment, a diagnosis of paraneoplastic acanthosis nigricans with secondary candidal infection was made. Drug-induced cheilitis was considered; however, improvement with discontinuation of the suspected offending drug would have been expected. Although chronic mucocutaneous candidiasis was possible, more prompt improvement upon initiation of systemic antifungal therapy would have been observed. Oral Crohn disease should be included in the differential, but it was unlikely given the lack of granulomas on pathology and absence of history of gastrointestinal tract symptoms. Melkersson-Rosenthal syndrome also was unlikely given the lack of facial nerve palsy as well as the lack of granulomas on pathology. Furthermore, none of these options would be associated with tripe palms, as seen in our patient.  

Acanthosis nigricans is a localized skin disorder characterized by hyperpigmented velvety plaques arising in flexural and intertriginous regions. Although most cases (80%) are associated with idiopathic or benign conditions, the link between acanthosis nigricans and an underlying malignancy has been well documented.^1-3 Most commonly associated with an underlying intra-abdominal malignancy (often gastric carcinoma), the lesions of paraneoplastic acanthosis nigricans are indistinguishable from their benign counterparts^.1,4 When the condition presents abruptly and extensively in a nonobese patient, prompt workup for malignancy should be initiated. Rapid onset and atypical distribution (ie, palmar, perioral, or mucosal) more commonly is associated with a paraneoplastic etiology.^5,6 

Histopathology for acanthosis nigricans shows hyperkeratosis and epidermal papillomatosis. Horn pseudocyst formation is possible, but usually no hyperpigmentation is observed. The findings typically are indistinguishable from seborrheic keratoses, epidermal nevi, or lesions of confluent and reticulated papillomatosis of Gougerot and Carteaud.² 

The underlying pathogenesis of acanthosis nigricans is poorly understood. In the benign subtype, insulin resistance commonly has been described. In the paraneoplastic subtype, it is proposed that the tumor produces a transforming growth factor that mimics epidermal growth factor and leads to keratinocyte proliferation.^7,8 Paraneoplastic acanthosis nigricans has the potential to arise at any point of tumor development, further contributing to the diagnostic challenge. Treatment of the skin lesions involves management of the underlying malignancy. Unfortunately, many such malignancies often are at an advanced stage, and subsequent prognosis is poor.² 

The Diagnosis: Paraneoplastic Acanthosis Nigricans 

Histopathologic examination demonstrated verrucous epidermal hyperplasia (Figure, A). Fungal organisms were identified with an Alcian blue and periodic acid-Schiff stain (Figure, B). The organisms demonstrated a vertical orientation in relation to the mucosal surface, which was consistent with candidal organisms.  

Given the rapid eruption of these plaques, the distribution on the oral and palmar surfaces (tripe palms), and the minimal improvement with both systemic steroids and antifungal treatment, a diagnosis of paraneoplastic acanthosis nigricans with secondary candidal infection was made. Drug-induced cheilitis was considered; however, improvement with discontinuation of the suspected offending drug would have been expected. Although chronic mucocutaneous candidiasis was possible, more prompt improvement upon initiation of systemic antifungal therapy would have been observed. Oral Crohn disease should be included in the differential, but it was unlikely given the lack of granulomas on pathology and absence of history of gastrointestinal tract symptoms. Melkersson-Rosenthal syndrome also was unlikely given the lack of facial nerve palsy as well as the lack of granulomas on pathology. Furthermore, none of these options would be associated with tripe palms, as seen in our patient.  

Acanthosis nigricans is a localized skin disorder characterized by hyperpigmented velvety plaques arising in flexural and intertriginous regions. Although most cases (80%) are associated with idiopathic or benign conditions, the link between acanthosis nigricans and an underlying malignancy has been well documented.^1-3 Most commonly associated with an underlying intra-abdominal malignancy (often gastric carcinoma), the lesions of paraneoplastic acanthosis nigricans are indistinguishable from their benign counterparts^.1,4 When the condition presents abruptly and extensively in a nonobese patient, prompt workup for malignancy should be initiated. Rapid onset and atypical distribution (ie, palmar, perioral, or mucosal) more commonly is associated with a paraneoplastic etiology.^5,6 

Histopathology for acanthosis nigricans shows hyperkeratosis and epidermal papillomatosis. Horn pseudocyst formation is possible, but usually no hyperpigmentation is observed. The findings typically are indistinguishable from seborrheic keratoses, epidermal nevi, or lesions of confluent and reticulated papillomatosis of Gougerot and Carteaud.² 

The underlying pathogenesis of acanthosis nigricans is poorly understood. In the benign subtype, insulin resistance commonly has been described. In the paraneoplastic subtype, it is proposed that the tumor produces a transforming growth factor that mimics epidermal growth factor and leads to keratinocyte proliferation.^7,8 Paraneoplastic acanthosis nigricans has the potential to arise at any point of tumor development, further contributing to the diagnostic challenge. Treatment of the skin lesions involves management of the underlying malignancy. Unfortunately, many such malignancies often are at an advanced stage, and subsequent prognosis is poor.² 

The Diagnosis: Favre-Racouchot Syndrome

Favre-Racouchot syndrome, also known as nodular elastosis with cysts and comedones, is seen in approximately 6% of adults aged 40 to 60 years and predominantly is observed in White males.¹ Typically, patients have a history of prolonged recreational or occupational UV exposure and tobacco use. The diagnosis can be made clinically; no biopsy is necessary. If a biopsy is performed, histologic findings typically consist of notable actinic elastosis, epidermal atrophy, and comedones. The differential diagnosis includes acne comedones, colloid milium, milia, chloracne, and trichoepithelioma.² Associated conditions that have been found concurrently include cutis rhomboidalis nuchae, actinic keratosis, erosive pustular dermatosis, actinic granuloma, and basal and squamous cell carcinomas.²

The pathogenesis, while not fully understood, seems to involve a combination of chronic UV radiation exposure and heavy cigarette smoking that eventually leads to cutaneous atrophy and keratinization of the pilosebaceous follicles as well as the formation of comedones.² Radiation therapy also has been implicated as a possible causative agent of Favre-Racouchot syndrome.¹ Clinically, symmetric distribution of large black comedones over the temporal and periorbital areas is seen surrounded by distinct signs of UV-damaged skin, including wrinkles and atrophic skin.³ Although there seems to be a synergistic effect between cigarette smoking and chronic UV exposure, evidence favors smoking as the major cause of this condition,^4,5 which causes striking visual changes but is a benign process. UV protection and smoking cessation are the most important factors for prevention and limiting progression.

Treatment consists of typical comedonal therapies such as tretinoin or comedone extraction. Procedural options in conjunction with medical therapy include dermabrasion or laser therapy. Newer studies have shown promising results for both CO₂ laser treatment and plasma exeresis.⁶ Plasma exeresis is a noninvasive technique that causes ionization of atmospheric gas between the device and tissue, ultimately causing sublimation of the target tissue.⁷ It is important to carefully evaluate and follow up with these patients due to their history of extensive UV exposure. Both short-term and long-term follow-up is recommended due to high rates of reoccurrence within 10 to 12 months and the dangers of chronic UV exposure– related malignancies.⁶

The Diagnosis: Favre-Racouchot Syndrome

Favre-Racouchot syndrome, also known as nodular elastosis with cysts and comedones, is seen in approximately 6% of adults aged 40 to 60 years and predominantly is observed in White males.¹ Typically, patients have a history of prolonged recreational or occupational UV exposure and tobacco use. The diagnosis can be made clinically; no biopsy is necessary. If a biopsy is performed, histologic findings typically consist of notable actinic elastosis, epidermal atrophy, and comedones. The differential diagnosis includes acne comedones, colloid milium, milia, chloracne, and trichoepithelioma.² Associated conditions that have been found concurrently include cutis rhomboidalis nuchae, actinic keratosis, erosive pustular dermatosis, actinic granuloma, and basal and squamous cell carcinomas.²

The pathogenesis, while not fully understood, seems to involve a combination of chronic UV radiation exposure and heavy cigarette smoking that eventually leads to cutaneous atrophy and keratinization of the pilosebaceous follicles as well as the formation of comedones.² Radiation therapy also has been implicated as a possible causative agent of Favre-Racouchot syndrome.¹ Clinically, symmetric distribution of large black comedones over the temporal and periorbital areas is seen surrounded by distinct signs of UV-damaged skin, including wrinkles and atrophic skin.³ Although there seems to be a synergistic effect between cigarette smoking and chronic UV exposure, evidence favors smoking as the major cause of this condition,^4,5 which causes striking visual changes but is a benign process. UV protection and smoking cessation are the most important factors for prevention and limiting progression.

Treatment consists of typical comedonal therapies such as tretinoin or comedone extraction. Procedural options in conjunction with medical therapy include dermabrasion or laser therapy. Newer studies have shown promising results for both CO₂ laser treatment and plasma exeresis.⁶ Plasma exeresis is a noninvasive technique that causes ionization of atmospheric gas between the device and tissue, ultimately causing sublimation of the target tissue.⁷ It is important to carefully evaluate and follow up with these patients due to their history of extensive UV exposure. Both short-term and long-term follow-up is recommended due to high rates of reoccurrence within 10 to 12 months and the dangers of chronic UV exposure– related malignancies.⁶

The Diagnosis: Favre-Racouchot Syndrome

Favre-Racouchot syndrome, also known as nodular elastosis with cysts and comedones, is seen in approximately 6% of adults aged 40 to 60 years and predominantly is observed in White males.¹ Typically, patients have a history of prolonged recreational or occupational UV exposure and tobacco use. The diagnosis can be made clinically; no biopsy is necessary. If a biopsy is performed, histologic findings typically consist of notable actinic elastosis, epidermal atrophy, and comedones. The differential diagnosis includes acne comedones, colloid milium, milia, chloracne, and trichoepithelioma.² Associated conditions that have been found concurrently include cutis rhomboidalis nuchae, actinic keratosis, erosive pustular dermatosis, actinic granuloma, and basal and squamous cell carcinomas.²

The pathogenesis, while not fully understood, seems to involve a combination of chronic UV radiation exposure and heavy cigarette smoking that eventually leads to cutaneous atrophy and keratinization of the pilosebaceous follicles as well as the formation of comedones.² Radiation therapy also has been implicated as a possible causative agent of Favre-Racouchot syndrome.¹ Clinically, symmetric distribution of large black comedones over the temporal and periorbital areas is seen surrounded by distinct signs of UV-damaged skin, including wrinkles and atrophic skin.³ Although there seems to be a synergistic effect between cigarette smoking and chronic UV exposure, evidence favors smoking as the major cause of this condition,^4,5 which causes striking visual changes but is a benign process. UV protection and smoking cessation are the most important factors for prevention and limiting progression.

Treatment consists of typical comedonal therapies such as tretinoin or comedone extraction. Procedural options in conjunction with medical therapy include dermabrasion or laser therapy. Newer studies have shown promising results for both CO₂ laser treatment and plasma exeresis.⁶ Plasma exeresis is a noninvasive technique that causes ionization of atmospheric gas between the device and tissue, ultimately causing sublimation of the target tissue.⁷ It is important to carefully evaluate and follow up with these patients due to their history of extensive UV exposure. Both short-term and long-term follow-up is recommended due to high rates of reoccurrence within 10 to 12 months and the dangers of chronic UV exposure– related malignancies.⁶

The Diagnosis: Cutaneous Cryptococcosis 

Histologic examination revealed infiltration of the dermis and subcutaneous tissue with rounded basophilic cells on low magnification (Figure 1A). On higher magnification, encapsulated yeast cells (cryptococci) of varying size accompanied by chronic granulomatous inflammatory infiltration with occasional giant cells were seen (Figure 1B). Alcian blue stain showed mucinous capsular material (Figure 1C). There was no history of diabetes mellitus, tuberculosis, steroid therapy, or immunosuppression. Moreover, systemic involvement or systemic focus of infection was ruled out after computed tomography of the head, chest, and abdomen. Therefore, the diagnosis of primary cutaneous cryptococcosis (PCC) was established. The patient was started on oral itraconazole 100 mg twice daily along with 5 drops of a saturated solution of potassium iodide 3 times daily that later was increased to 20 drops 3 times daily at a weekly interval. The lesions started improving after 1 month and healed completely after 9 months of treatment (Figure 2). 

Primary cutaneous cryptococcosis is the identification of Cryptococcus neoformans in a skin lesion without evidence of simultaneous disseminated disease. Neuville et al¹ observed that skin lesions resemble cellulitis, ulcerations, or whitlows and were located on unclothed areas. In contrast, lesions from disseminated disease presented as scattered umbilicated papules resembling molluscum contagiosum. Diagnosis of PCC is based on the observation of encapsulated yeasts by direct microscopic examination, isolation of C neoformans or Cryptococcus gattii in culture, and by the demonstration of capsular antigen in various fluids, including serum and cerebrospinal fluid by latex particle agglutination or enzyme-linked immunosorbent assay. Histologically, Cryptococcus species produce a proliferative inflammatory reaction in immunocompetent hosts with the formation of compact epithelioid granulomas, with giant cells and a peripheral layer of lymphocytes. Treatment options for PCC infection range from antifungal medications and surgical debridement to observation. 

The differential diagnosis may include cutaneous leishmaniasis, cutaneous tuberculosis, cutaneous histoplasmosis, and basal cell carcinoma. These entities may have similar presentations and can only be confidently differentiated on direct microscopy and histopathologic examination. The characteristic Leishmania donovani bodies on microscopy in cutaneous leishmaniasis and tubercular granuloma with central necrosis on histology in cutaneous tuberculosis can differentiate these conditions from cryptococcosis. In some patients with cryptococcosis, the yeast may produce a less characteristic polysaccharide capsule and thus may be confused with histoplasmosis. Fontana-Masson staining may show melanin-producing yeast, which is characteristic of cryptococci.² Ulcerated basal cell carcinoma may present similar clinically; however, histopathology will rule it out. 

Cutaneous cryptococcal infection should be presumed to be disseminated until proven otherwise, and a search for other sites of involvement must immediately be undertaken. Cutaneous signs may be the first indication of infection, preceding the diagnosis of disseminated disease by 2 to 8 months, making its recognition crucial to early treatment. It is not possible to diagnose PCC on a specific clinical manifestation because a diverse range of skin lesions may be present. Therefore, culture and histology are the gold standards for diagnosis of cryptococcosis. 

The Diagnosis: Cutaneous Cryptococcosis 

Histologic examination revealed infiltration of the dermis and subcutaneous tissue with rounded basophilic cells on low magnification (Figure 1A). On higher magnification, encapsulated yeast cells (cryptococci) of varying size accompanied by chronic granulomatous inflammatory infiltration with occasional giant cells were seen (Figure 1B). Alcian blue stain showed mucinous capsular material (Figure 1C). There was no history of diabetes mellitus, tuberculosis, steroid therapy, or immunosuppression. Moreover, systemic involvement or systemic focus of infection was ruled out after computed tomography of the head, chest, and abdomen. Therefore, the diagnosis of primary cutaneous cryptococcosis (PCC) was established. The patient was started on oral itraconazole 100 mg twice daily along with 5 drops of a saturated solution of potassium iodide 3 times daily that later was increased to 20 drops 3 times daily at a weekly interval. The lesions started improving after 1 month and healed completely after 9 months of treatment (Figure 2). 

Primary cutaneous cryptococcosis is the identification of Cryptococcus neoformans in a skin lesion without evidence of simultaneous disseminated disease. Neuville et al¹ observed that skin lesions resemble cellulitis, ulcerations, or whitlows and were located on unclothed areas. In contrast, lesions from disseminated disease presented as scattered umbilicated papules resembling molluscum contagiosum. Diagnosis of PCC is based on the observation of encapsulated yeasts by direct microscopic examination, isolation of C neoformans or Cryptococcus gattii in culture, and by the demonstration of capsular antigen in various fluids, including serum and cerebrospinal fluid by latex particle agglutination or enzyme-linked immunosorbent assay. Histologically, Cryptococcus species produce a proliferative inflammatory reaction in immunocompetent hosts with the formation of compact epithelioid granulomas, with giant cells and a peripheral layer of lymphocytes. Treatment options for PCC infection range from antifungal medications and surgical debridement to observation. 

The differential diagnosis may include cutaneous leishmaniasis, cutaneous tuberculosis, cutaneous histoplasmosis, and basal cell carcinoma. These entities may have similar presentations and can only be confidently differentiated on direct microscopy and histopathologic examination. The characteristic Leishmania donovani bodies on microscopy in cutaneous leishmaniasis and tubercular granuloma with central necrosis on histology in cutaneous tuberculosis can differentiate these conditions from cryptococcosis. In some patients with cryptococcosis, the yeast may produce a less characteristic polysaccharide capsule and thus may be confused with histoplasmosis. Fontana-Masson staining may show melanin-producing yeast, which is characteristic of cryptococci.² Ulcerated basal cell carcinoma may present similar clinically; however, histopathology will rule it out. 

Cutaneous cryptococcal infection should be presumed to be disseminated until proven otherwise, and a search for other sites of involvement must immediately be undertaken. Cutaneous signs may be the first indication of infection, preceding the diagnosis of disseminated disease by 2 to 8 months, making its recognition crucial to early treatment. It is not possible to diagnose PCC on a specific clinical manifestation because a diverse range of skin lesions may be present. Therefore, culture and histology are the gold standards for diagnosis of cryptococcosis. 

The Diagnosis: Cutaneous Cryptococcosis 

Histologic examination revealed infiltration of the dermis and subcutaneous tissue with rounded basophilic cells on low magnification (Figure 1A). On higher magnification, encapsulated yeast cells (cryptococci) of varying size accompanied by chronic granulomatous inflammatory infiltration with occasional giant cells were seen (Figure 1B). Alcian blue stain showed mucinous capsular material (Figure 1C). There was no history of diabetes mellitus, tuberculosis, steroid therapy, or immunosuppression. Moreover, systemic involvement or systemic focus of infection was ruled out after computed tomography of the head, chest, and abdomen. Therefore, the diagnosis of primary cutaneous cryptococcosis (PCC) was established. The patient was started on oral itraconazole 100 mg twice daily along with 5 drops of a saturated solution of potassium iodide 3 times daily that later was increased to 20 drops 3 times daily at a weekly interval. The lesions started improving after 1 month and healed completely after 9 months of treatment (Figure 2). 

Primary cutaneous cryptococcosis is the identification of Cryptococcus neoformans in a skin lesion without evidence of simultaneous disseminated disease. Neuville et al¹ observed that skin lesions resemble cellulitis, ulcerations, or whitlows and were located on unclothed areas. In contrast, lesions from disseminated disease presented as scattered umbilicated papules resembling molluscum contagiosum. Diagnosis of PCC is based on the observation of encapsulated yeasts by direct microscopic examination, isolation of C neoformans or Cryptococcus gattii in culture, and by the demonstration of capsular antigen in various fluids, including serum and cerebrospinal fluid by latex particle agglutination or enzyme-linked immunosorbent assay. Histologically, Cryptococcus species produce a proliferative inflammatory reaction in immunocompetent hosts with the formation of compact epithelioid granulomas, with giant cells and a peripheral layer of lymphocytes. Treatment options for PCC infection range from antifungal medications and surgical debridement to observation. 

The differential diagnosis may include cutaneous leishmaniasis, cutaneous tuberculosis, cutaneous histoplasmosis, and basal cell carcinoma. These entities may have similar presentations and can only be confidently differentiated on direct microscopy and histopathologic examination. The characteristic Leishmania donovani bodies on microscopy in cutaneous leishmaniasis and tubercular granuloma with central necrosis on histology in cutaneous tuberculosis can differentiate these conditions from cryptococcosis. In some patients with cryptococcosis, the yeast may produce a less characteristic polysaccharide capsule and thus may be confused with histoplasmosis. Fontana-Masson staining may show melanin-producing yeast, which is characteristic of cryptococci.² Ulcerated basal cell carcinoma may present similar clinically; however, histopathology will rule it out. 

Cutaneous cryptococcal infection should be presumed to be disseminated until proven otherwise, and a search for other sites of involvement must immediately be undertaken. Cutaneous signs may be the first indication of infection, preceding the diagnosis of disseminated disease by 2 to 8 months, making its recognition crucial to early treatment. It is not possible to diagnose PCC on a specific clinical manifestation because a diverse range of skin lesions may be present. Therefore, culture and histology are the gold standards for diagnosis of cryptococcosis. 

The Diagnosis: Trichodysplasia Spinulosa 

Trichodysplasia spinulosa has been described in case reports over the last several decades, with its causative virus trichodysplasia spinulosa-associated polyomavirus (TSPyV) identified in 2010 by van der Meijden et al.¹ Trichodysplasia spinulosa-associated polyomavirus is a small, nonenveloped, double-stranded DNA virus in the Polyomaviridae family, among several other known cutaneous polyomaviruses including Merkel cell polyomavirus, human polyomavirus (HPyV) 6, HPyV7, HPyV10, and possibly HPyV13.² The primary target of TSPyV is follicular keratinocytes, and it is believed to cause trichodysplasia spinulosa by primary infection rather than by reactivation. Trichodysplasia spinulosa presents in immunosuppressed patients as a folliculocentric eruption of papules with keratinous spines on the face, often with concurrent alopecia, eventually spreading to the trunk and extremities.³ The diagnosis often is clinical, but a biopsy may be performed for histopathologic confirmation. Alternatively, lesional spicules can be painlessly collected manually and submitted for viral polymerase chain reaction (PCR).⁴ The diagnosis of trichodysplasia spinulosa can be difficult due to similarities with other more common conditions such as keratosis pilaris, milia, filiform warts, or lichen spinulosus.  

Similar to trichodysplasia spinulosa, keratosis pilaris also presents with folliculocentric and often erythematous papules.⁵ Keratosis pilaris most frequently affects the posterior upper arms and thighs but also may affect the cheeks, as seen in trichodysplasia spinulosa. Differentiation between the 2 diagnoses can be made on a clinical basis, as keratosis pilaris lacks the characteristic keratinous spines and often spares the central face and nose, locations that commonly are affected in trichodysplasia spinulosa.³ 

Milia typically appear as white to yellow papules, often on the cheeks, eyelids, nose, and chin.⁶ Given their predilection for the face, milia can appear similarly to trichodysplasia spinulosa. Differentiation can be made clinically, as milia typically are not as numerous as the spiculed papules seen in trichodysplasia spinulosa. Morphologically, milia will present as smooth, dome-shaped papules as opposed to the keratinous spicules seen in trichodysplasia spinulosa. The diagnosis of milia can be confirmed by incision and removal of the white chalky keratin core, a feature absent in trichodysplasia spinulosa.  

Filiform warts are benign epidermal proliferations caused by human papillomavirus infection that manifest as flesh-colored, verrucous, hyperkeratotic papules.⁷ They can appear on virtually any skin surface, including the face, and thus may be mistaken for trichodysplasia spinulosa. Close inspection usually will reveal tiny black dots that represent thrombosed capillaries, a feature lacking in trichodysplasia spinulosa. In long-standing lesions or immunocompromised patients, confluent verrucous plaques may develop.⁸ Diagnosis of filiform warts can be confirmed with biopsy, which will demonstrate a compact stratum corneum, coarse hypergranulosis, and papillomatosis curving inward, while biopsy of a trichodysplasia spinulosa lesion would show polyomavirus infection of the hair follicle and characteristic eosinophilic inclusion bodies.⁹ 

Lichen spinulosus may appear as multiple folliculocentric scaly papules with hairlike horny spines.¹⁰ Lichen spinulosus differs from trichodysplasia spinulosa in that it commonly appears on the neck, abdomen, trochanteric region, arms, elbows, or knees. Lichen spinulosus also classically appears as a concrete cluster of papules, often localized to a certain region, in contrast to trichodysplasia spinulosa, which will be widespread, often spreading over time. Finally, clinical history may help differentiate the 2 entities. Lichen spinulosus most often appears in children and adolescents and often has an indolent course, typically resolving during puberty, while trichodysplasia spinulosa is seen in immunocompromised patients. 

In our patient, the dermatology team made a diagnosis of trichodysplasia spinulosa based on the characteristic clinical presentation, which was confirmed after approximately 10 lesional spicules were removed by tissue forceps and submitted for PCR analysis showing TSPyV (Figure). Two other cases utilized spicule PCR analysis for confirmation of TSPyV.^11,12 This technique may represent a viable option for diagnostic confirmation in pediatric cases. 

Although some articles have examined the molecular and biologic features of trichodysplasia spinulosa, literature on clinical presentation and management is limited to isolated case reports with no comprehensive studies to establish a standardized treatment. Of these reports, oral valganciclovir 900 mg daily, topical retinoids, cidofovir cream 1% to 3%, and decreasing or altering the immunosuppressive regimen all have been noted to provide clinical improvement.^13,14 Other therapies including leflunomide and routine manual extraction of spicules also have shown effectiveness in the treatment of trichodysplasia spinulosa.¹⁵  

In our patient, treatment included decreasing immunosuppression, as she was getting recurrent sinus and upper respiratory infections. Mycophenolate mofetil was discontinued, and the patient was continued solely on tacrolimus therapy. She demonstrated notable improvement after 3 months, with approximately 50% clearance of the eruption. A mutual decision was made at that visit to initiate therapy with compounded cidofovir cream 1% daily to the lesions until the next follow-up visit. Unfortunately, the patient did not return for her scheduled dermatology visits and was lost to long-term follow-up. 

Acknowledgment
We thank Richard C. Wang, MD, PhD (Dallas, Texas), for his dermatologic expertise and assistance in analysis of lesional samples for TSPyV. 

The Diagnosis: Trichodysplasia Spinulosa 

Trichodysplasia spinulosa has been described in case reports over the last several decades, with its causative virus trichodysplasia spinulosa-associated polyomavirus (TSPyV) identified in 2010 by van der Meijden et al.¹ Trichodysplasia spinulosa-associated polyomavirus is a small, nonenveloped, double-stranded DNA virus in the Polyomaviridae family, among several other known cutaneous polyomaviruses including Merkel cell polyomavirus, human polyomavirus (HPyV) 6, HPyV7, HPyV10, and possibly HPyV13.² The primary target of TSPyV is follicular keratinocytes, and it is believed to cause trichodysplasia spinulosa by primary infection rather than by reactivation. Trichodysplasia spinulosa presents in immunosuppressed patients as a folliculocentric eruption of papules with keratinous spines on the face, often with concurrent alopecia, eventually spreading to the trunk and extremities.³ The diagnosis often is clinical, but a biopsy may be performed for histopathologic confirmation. Alternatively, lesional spicules can be painlessly collected manually and submitted for viral polymerase chain reaction (PCR).⁴ The diagnosis of trichodysplasia spinulosa can be difficult due to similarities with other more common conditions such as keratosis pilaris, milia, filiform warts, or lichen spinulosus.  

Similar to trichodysplasia spinulosa, keratosis pilaris also presents with folliculocentric and often erythematous papules.⁵ Keratosis pilaris most frequently affects the posterior upper arms and thighs but also may affect the cheeks, as seen in trichodysplasia spinulosa. Differentiation between the 2 diagnoses can be made on a clinical basis, as keratosis pilaris lacks the characteristic keratinous spines and often spares the central face and nose, locations that commonly are affected in trichodysplasia spinulosa.³ 

Milia typically appear as white to yellow papules, often on the cheeks, eyelids, nose, and chin.⁶ Given their predilection for the face, milia can appear similarly to trichodysplasia spinulosa. Differentiation can be made clinically, as milia typically are not as numerous as the spiculed papules seen in trichodysplasia spinulosa. Morphologically, milia will present as smooth, dome-shaped papules as opposed to the keratinous spicules seen in trichodysplasia spinulosa. The diagnosis of milia can be confirmed by incision and removal of the white chalky keratin core, a feature absent in trichodysplasia spinulosa.  

Filiform warts are benign epidermal proliferations caused by human papillomavirus infection that manifest as flesh-colored, verrucous, hyperkeratotic papules.⁷ They can appear on virtually any skin surface, including the face, and thus may be mistaken for trichodysplasia spinulosa. Close inspection usually will reveal tiny black dots that represent thrombosed capillaries, a feature lacking in trichodysplasia spinulosa. In long-standing lesions or immunocompromised patients, confluent verrucous plaques may develop.⁸ Diagnosis of filiform warts can be confirmed with biopsy, which will demonstrate a compact stratum corneum, coarse hypergranulosis, and papillomatosis curving inward, while biopsy of a trichodysplasia spinulosa lesion would show polyomavirus infection of the hair follicle and characteristic eosinophilic inclusion bodies.⁹ 

Lichen spinulosus may appear as multiple folliculocentric scaly papules with hairlike horny spines.¹⁰ Lichen spinulosus differs from trichodysplasia spinulosa in that it commonly appears on the neck, abdomen, trochanteric region, arms, elbows, or knees. Lichen spinulosus also classically appears as a concrete cluster of papules, often localized to a certain region, in contrast to trichodysplasia spinulosa, which will be widespread, often spreading over time. Finally, clinical history may help differentiate the 2 entities. Lichen spinulosus most often appears in children and adolescents and often has an indolent course, typically resolving during puberty, while trichodysplasia spinulosa is seen in immunocompromised patients. 

In our patient, the dermatology team made a diagnosis of trichodysplasia spinulosa based on the characteristic clinical presentation, which was confirmed after approximately 10 lesional spicules were removed by tissue forceps and submitted for PCR analysis showing TSPyV (Figure). Two other cases utilized spicule PCR analysis for confirmation of TSPyV.^11,12 This technique may represent a viable option for diagnostic confirmation in pediatric cases. 

Although some articles have examined the molecular and biologic features of trichodysplasia spinulosa, literature on clinical presentation and management is limited to isolated case reports with no comprehensive studies to establish a standardized treatment. Of these reports, oral valganciclovir 900 mg daily, topical retinoids, cidofovir cream 1% to 3%, and decreasing or altering the immunosuppressive regimen all have been noted to provide clinical improvement.^13,14 Other therapies including leflunomide and routine manual extraction of spicules also have shown effectiveness in the treatment of trichodysplasia spinulosa.¹⁵  

In our patient, treatment included decreasing immunosuppression, as she was getting recurrent sinus and upper respiratory infections. Mycophenolate mofetil was discontinued, and the patient was continued solely on tacrolimus therapy. She demonstrated notable improvement after 3 months, with approximately 50% clearance of the eruption. A mutual decision was made at that visit to initiate therapy with compounded cidofovir cream 1% daily to the lesions until the next follow-up visit. Unfortunately, the patient did not return for her scheduled dermatology visits and was lost to long-term follow-up. 

Acknowledgment
We thank Richard C. Wang, MD, PhD (Dallas, Texas), for his dermatologic expertise and assistance in analysis of lesional samples for TSPyV. 

The Diagnosis: Trichodysplasia Spinulosa 

Trichodysplasia spinulosa has been described in case reports over the last several decades, with its causative virus trichodysplasia spinulosa-associated polyomavirus (TSPyV) identified in 2010 by van der Meijden et al.¹ Trichodysplasia spinulosa-associated polyomavirus is a small, nonenveloped, double-stranded DNA virus in the Polyomaviridae family, among several other known cutaneous polyomaviruses including Merkel cell polyomavirus, human polyomavirus (HPyV) 6, HPyV7, HPyV10, and possibly HPyV13.² The primary target of TSPyV is follicular keratinocytes, and it is believed to cause trichodysplasia spinulosa by primary infection rather than by reactivation. Trichodysplasia spinulosa presents in immunosuppressed patients as a folliculocentric eruption of papules with keratinous spines on the face, often with concurrent alopecia, eventually spreading to the trunk and extremities.³ The diagnosis often is clinical, but a biopsy may be performed for histopathologic confirmation. Alternatively, lesional spicules can be painlessly collected manually and submitted for viral polymerase chain reaction (PCR).⁴ The diagnosis of trichodysplasia spinulosa can be difficult due to similarities with other more common conditions such as keratosis pilaris, milia, filiform warts, or lichen spinulosus.  

Similar to trichodysplasia spinulosa, keratosis pilaris also presents with folliculocentric and often erythematous papules.⁵ Keratosis pilaris most frequently affects the posterior upper arms and thighs but also may affect the cheeks, as seen in trichodysplasia spinulosa. Differentiation between the 2 diagnoses can be made on a clinical basis, as keratosis pilaris lacks the characteristic keratinous spines and often spares the central face and nose, locations that commonly are affected in trichodysplasia spinulosa.³ 

Milia typically appear as white to yellow papules, often on the cheeks, eyelids, nose, and chin.⁶ Given their predilection for the face, milia can appear similarly to trichodysplasia spinulosa. Differentiation can be made clinically, as milia typically are not as numerous as the spiculed papules seen in trichodysplasia spinulosa. Morphologically, milia will present as smooth, dome-shaped papules as opposed to the keratinous spicules seen in trichodysplasia spinulosa. The diagnosis of milia can be confirmed by incision and removal of the white chalky keratin core, a feature absent in trichodysplasia spinulosa.  

Filiform warts are benign epidermal proliferations caused by human papillomavirus infection that manifest as flesh-colored, verrucous, hyperkeratotic papules.⁷ They can appear on virtually any skin surface, including the face, and thus may be mistaken for trichodysplasia spinulosa. Close inspection usually will reveal tiny black dots that represent thrombosed capillaries, a feature lacking in trichodysplasia spinulosa. In long-standing lesions or immunocompromised patients, confluent verrucous plaques may develop.⁸ Diagnosis of filiform warts can be confirmed with biopsy, which will demonstrate a compact stratum corneum, coarse hypergranulosis, and papillomatosis curving inward, while biopsy of a trichodysplasia spinulosa lesion would show polyomavirus infection of the hair follicle and characteristic eosinophilic inclusion bodies.⁹ 

Lichen spinulosus may appear as multiple folliculocentric scaly papules with hairlike horny spines.¹⁰ Lichen spinulosus differs from trichodysplasia spinulosa in that it commonly appears on the neck, abdomen, trochanteric region, arms, elbows, or knees. Lichen spinulosus also classically appears as a concrete cluster of papules, often localized to a certain region, in contrast to trichodysplasia spinulosa, which will be widespread, often spreading over time. Finally, clinical history may help differentiate the 2 entities. Lichen spinulosus most often appears in children and adolescents and often has an indolent course, typically resolving during puberty, while trichodysplasia spinulosa is seen in immunocompromised patients. 

In our patient, the dermatology team made a diagnosis of trichodysplasia spinulosa based on the characteristic clinical presentation, which was confirmed after approximately 10 lesional spicules were removed by tissue forceps and submitted for PCR analysis showing TSPyV (Figure). Two other cases utilized spicule PCR analysis for confirmation of TSPyV.^11,12 This technique may represent a viable option for diagnostic confirmation in pediatric cases. 

Although some articles have examined the molecular and biologic features of trichodysplasia spinulosa, literature on clinical presentation and management is limited to isolated case reports with no comprehensive studies to establish a standardized treatment. Of these reports, oral valganciclovir 900 mg daily, topical retinoids, cidofovir cream 1% to 3%, and decreasing or altering the immunosuppressive regimen all have been noted to provide clinical improvement.^13,14 Other therapies including leflunomide and routine manual extraction of spicules also have shown effectiveness in the treatment of trichodysplasia spinulosa.¹⁵  

In our patient, treatment included decreasing immunosuppression, as she was getting recurrent sinus and upper respiratory infections. Mycophenolate mofetil was discontinued, and the patient was continued solely on tacrolimus therapy. She demonstrated notable improvement after 3 months, with approximately 50% clearance of the eruption. A mutual decision was made at that visit to initiate therapy with compounded cidofovir cream 1% daily to the lesions until the next follow-up visit. Unfortunately, the patient did not return for her scheduled dermatology visits and was lost to long-term follow-up. 

Acknowledgment
We thank Richard C. Wang, MD, PhD (Dallas, Texas), for his dermatologic expertise and assistance in analysis of lesional samples for TSPyV. 

The Diagnosis: Primary Cutaneous Anaplastic Large Cell Lymphoma  

Microscopic analysis showed a dense proliferation of mononuclear cells filling and expanding the dermis with focal epidermotropism (Figure 1). Immunohistochemistry demonstrated strong and diffuse staining for CD3, CD4, and CD30 (Figure 2) and lack of staining for anaplastic lymphoma kinase (ALK). Workup to exclude systemic disease was initiated and included unremarkable computed tomography (CT) of the neck, chest, abdomen, and pelvis along with no abnormal cells on bone marrow biopsy. Complete blood cell count, basic metabolic panel, and lactate dehydrogenase were within reference range. Given the lack of evidence for systemic involvement, a diagnosis of primary cutaneous anaplastic large cell lymphoma (PC-ALCL) was made. The treatment plan for our patient with a solitary lesion was localized radiation therapy. 

Primary cutaneous CD30⁺ lymphoproliferative disorders encompass a spectrum of conditions, with premalignant lymphomatoid papulosis (LyP) at one extreme and the malignant PC-ALCL on the other.¹ The diagnosis of PC-ALCL is made by clinicopathologic correlation, and lesions typically present abruptly as solitary or grouped nodules with a tendency to ulcerate over time. Spontaneous regression has been reported, but relapse in the skin is frequent.² 

A representative, typically excisional, biopsy should be performed if the clinician suspects PC-ALCL. Histologic criteria include a dense dermal infiltrate of large pleomorphic cells and the expression of CD30 in at least 75% of tumor cells.³ Primary cutaneous anaplastic large cell lymphoma typically lacks the ALK gene translocation with the nucleophosmin gene, NPM, that is common in systemic disease; however, a small subset of PC-ALCL may be ALK positive and indicate a higher chance of transformation into systemic disease.²

 The extent of the lymphoma should be staged to exclude the possibility of systemic disease. This assessment includes a complete physical examination; laboratory investigation, including complete blood cell count with differential and blood chemistries; and radiography. A positron emission tomography-CT scan of the neck, chest, abdomen, and pelvis, or a whole-body integrated positron emission tomography-CT are sufficient for the radiographic examination.³ 

The initial choice of treatment for solitary or localized PC-ALCL is localized radiation therapy or low-dose methotrexate. Targeted therapy such as brentuximab has been shown to be effective for those with multifocal systemic involvement or refractory disease.² Cure rates from radiation therapy alone approach 95%.³ It is important to highlight radiation therapy as the initial management plan to increase awareness and to avoid inappropriate treatment of PC-ALCL with traditional chemotherapy. 

Large lesions of LyP may appear similar to PC-ALCL on histopathology, making the two entities difficult to distinguish. However, in contrast to PC-ALCL, LyP classically has a different clinical course characterized by waxing and waning crops of lesions that typically are smaller (<1 cm) than those of PC-ALCL.² Large cell transformation of mycosis fungoides is another entity to consider, but these patients usually have a known history of mycosis fungoides.⁴ 

Keratoacanthomas, considered to be a variant of a well-differentiated squamous cell carcinoma, present as rapidly enlarging crateriform nodules with a keratotic core. They usually are found on the head and neck or sun-exposed areas of the extremities and may regress spontaneously.⁵ Histology will show atypical, highly differentiated squamous epithelia. Merkel cell carcinoma also has a predilection for the head and neck in older patients and may present as a rapidly growing nodule. However, histology will show an aggressive tumor with small round blue cells, and immunohistochemistry will show the characteristic paranuclear dot staining for CK20 along with staining for various neuroendocrine markers. Similarly, atypical fibroxanthoma is a low-grade sarcoma that also presents on the head and neck of elderly sun-damaged patients.⁵ Histology will show dermal proliferation of spindle cells that often extend up against the epidermis along with pleomorphism and atypical mitoses. Basal cell carcinoma is a common tumor that can present on the head and neck in sun-damaged patients. Nodular basal cell carcinomas can enlarge and ulcerate, but growth is seen over years rather than weeks.⁵ Histology characteristically will show tumor islands composed of basaloid cells with peripheral palisading and clefting between the tumor islands and the stroma.  

The Diagnosis: Primary Cutaneous Anaplastic Large Cell Lymphoma  

Microscopic analysis showed a dense proliferation of mononuclear cells filling and expanding the dermis with focal epidermotropism (Figure 1). Immunohistochemistry demonstrated strong and diffuse staining for CD3, CD4, and CD30 (Figure 2) and lack of staining for anaplastic lymphoma kinase (ALK). Workup to exclude systemic disease was initiated and included unremarkable computed tomography (CT) of the neck, chest, abdomen, and pelvis along with no abnormal cells on bone marrow biopsy. Complete blood cell count, basic metabolic panel, and lactate dehydrogenase were within reference range. Given the lack of evidence for systemic involvement, a diagnosis of primary cutaneous anaplastic large cell lymphoma (PC-ALCL) was made. The treatment plan for our patient with a solitary lesion was localized radiation therapy. 

Primary cutaneous CD30⁺ lymphoproliferative disorders encompass a spectrum of conditions, with premalignant lymphomatoid papulosis (LyP) at one extreme and the malignant PC-ALCL on the other.¹ The diagnosis of PC-ALCL is made by clinicopathologic correlation, and lesions typically present abruptly as solitary or grouped nodules with a tendency to ulcerate over time. Spontaneous regression has been reported, but relapse in the skin is frequent.² 

A representative, typically excisional, biopsy should be performed if the clinician suspects PC-ALCL. Histologic criteria include a dense dermal infiltrate of large pleomorphic cells and the expression of CD30 in at least 75% of tumor cells.³ Primary cutaneous anaplastic large cell lymphoma typically lacks the ALK gene translocation with the nucleophosmin gene, NPM, that is common in systemic disease; however, a small subset of PC-ALCL may be ALK positive and indicate a higher chance of transformation into systemic disease.²

 The extent of the lymphoma should be staged to exclude the possibility of systemic disease. This assessment includes a complete physical examination; laboratory investigation, including complete blood cell count with differential and blood chemistries; and radiography. A positron emission tomography-CT scan of the neck, chest, abdomen, and pelvis, or a whole-body integrated positron emission tomography-CT are sufficient for the radiographic examination.³ 

The initial choice of treatment for solitary or localized PC-ALCL is localized radiation therapy or low-dose methotrexate. Targeted therapy such as brentuximab has been shown to be effective for those with multifocal systemic involvement or refractory disease.² Cure rates from radiation therapy alone approach 95%.³ It is important to highlight radiation therapy as the initial management plan to increase awareness and to avoid inappropriate treatment of PC-ALCL with traditional chemotherapy. 

Large lesions of LyP may appear similar to PC-ALCL on histopathology, making the two entities difficult to distinguish. However, in contrast to PC-ALCL, LyP classically has a different clinical course characterized by waxing and waning crops of lesions that typically are smaller (<1 cm) than those of PC-ALCL.² Large cell transformation of mycosis fungoides is another entity to consider, but these patients usually have a known history of mycosis fungoides.⁴ 

Keratoacanthomas, considered to be a variant of a well-differentiated squamous cell carcinoma, present as rapidly enlarging crateriform nodules with a keratotic core. They usually are found on the head and neck or sun-exposed areas of the extremities and may regress spontaneously.⁵ Histology will show atypical, highly differentiated squamous epithelia. Merkel cell carcinoma also has a predilection for the head and neck in older patients and may present as a rapidly growing nodule. However, histology will show an aggressive tumor with small round blue cells, and immunohistochemistry will show the characteristic paranuclear dot staining for CK20 along with staining for various neuroendocrine markers. Similarly, atypical fibroxanthoma is a low-grade sarcoma that also presents on the head and neck of elderly sun-damaged patients.⁵ Histology will show dermal proliferation of spindle cells that often extend up against the epidermis along with pleomorphism and atypical mitoses. Basal cell carcinoma is a common tumor that can present on the head and neck in sun-damaged patients. Nodular basal cell carcinomas can enlarge and ulcerate, but growth is seen over years rather than weeks.⁵ Histology characteristically will show tumor islands composed of basaloid cells with peripheral palisading and clefting between the tumor islands and the stroma.  

The Diagnosis: Primary Cutaneous Anaplastic Large Cell Lymphoma  

Microscopic analysis showed a dense proliferation of mononuclear cells filling and expanding the dermis with focal epidermotropism (Figure 1). Immunohistochemistry demonstrated strong and diffuse staining for CD3, CD4, and CD30 (Figure 2) and lack of staining for anaplastic lymphoma kinase (ALK). Workup to exclude systemic disease was initiated and included unremarkable computed tomography (CT) of the neck, chest, abdomen, and pelvis along with no abnormal cells on bone marrow biopsy. Complete blood cell count, basic metabolic panel, and lactate dehydrogenase were within reference range. Given the lack of evidence for systemic involvement, a diagnosis of primary cutaneous anaplastic large cell lymphoma (PC-ALCL) was made. The treatment plan for our patient with a solitary lesion was localized radiation therapy. 

Primary cutaneous CD30⁺ lymphoproliferative disorders encompass a spectrum of conditions, with premalignant lymphomatoid papulosis (LyP) at one extreme and the malignant PC-ALCL on the other.¹ The diagnosis of PC-ALCL is made by clinicopathologic correlation, and lesions typically present abruptly as solitary or grouped nodules with a tendency to ulcerate over time. Spontaneous regression has been reported, but relapse in the skin is frequent.² 

A representative, typically excisional, biopsy should be performed if the clinician suspects PC-ALCL. Histologic criteria include a dense dermal infiltrate of large pleomorphic cells and the expression of CD30 in at least 75% of tumor cells.³ Primary cutaneous anaplastic large cell lymphoma typically lacks the ALK gene translocation with the nucleophosmin gene, NPM, that is common in systemic disease; however, a small subset of PC-ALCL may be ALK positive and indicate a higher chance of transformation into systemic disease.²

 The extent of the lymphoma should be staged to exclude the possibility of systemic disease. This assessment includes a complete physical examination; laboratory investigation, including complete blood cell count with differential and blood chemistries; and radiography. A positron emission tomography-CT scan of the neck, chest, abdomen, and pelvis, or a whole-body integrated positron emission tomography-CT are sufficient for the radiographic examination.³ 

The initial choice of treatment for solitary or localized PC-ALCL is localized radiation therapy or low-dose methotrexate. Targeted therapy such as brentuximab has been shown to be effective for those with multifocal systemic involvement or refractory disease.² Cure rates from radiation therapy alone approach 95%.³ It is important to highlight radiation therapy as the initial management plan to increase awareness and to avoid inappropriate treatment of PC-ALCL with traditional chemotherapy. 

Large lesions of LyP may appear similar to PC-ALCL on histopathology, making the two entities difficult to distinguish. However, in contrast to PC-ALCL, LyP classically has a different clinical course characterized by waxing and waning crops of lesions that typically are smaller (<1 cm) than those of PC-ALCL.² Large cell transformation of mycosis fungoides is another entity to consider, but these patients usually have a known history of mycosis fungoides.⁴ 

Keratoacanthomas, considered to be a variant of a well-differentiated squamous cell carcinoma, present as rapidly enlarging crateriform nodules with a keratotic core. They usually are found on the head and neck or sun-exposed areas of the extremities and may regress spontaneously.⁵ Histology will show atypical, highly differentiated squamous epithelia. Merkel cell carcinoma also has a predilection for the head and neck in older patients and may present as a rapidly growing nodule. However, histology will show an aggressive tumor with small round blue cells, and immunohistochemistry will show the characteristic paranuclear dot staining for CK20 along with staining for various neuroendocrine markers. Similarly, atypical fibroxanthoma is a low-grade sarcoma that also presents on the head and neck of elderly sun-damaged patients.⁵ Histology will show dermal proliferation of spindle cells that often extend up against the epidermis along with pleomorphism and atypical mitoses. Basal cell carcinoma is a common tumor that can present on the head and neck in sun-damaged patients. Nodular basal cell carcinomas can enlarge and ulcerate, but growth is seen over years rather than weeks.⁵ Histology characteristically will show tumor islands composed of basaloid cells with peripheral palisading and clefting between the tumor islands and the stroma.  

The Diagnosis: Demodicosis 

A clinical diagnosis of facial demodicosis triggered by topical corticosteroid therapy was suspected in our patient. A 3-mm punch biopsy of the right forehead demonstrated a follicular infundibulum rich in Demodex folliculorum with a discrete mononuclear infiltrate in the dermis (Figure 1), confirming the diagnosis. The patient was prescribed metronidazole gel 2% twice daily. Complete clearance of the facial rash was observed at 1-week follow-up (Figure 2). 

Demodex folliculorum is a mite that parasitizes the pilosebaceous follicles of human skin, becoming pathogenic with excessive colonization.^1-3 Facial demodicosis presents as pruritic papules and pustules in a pilosebaceous distribution on the face.^2,3 The diagnosis of facial demodicosis can be difficult due to similarities with many other common facial rashes such as acne, rosacea, contact dermatitis, and folliculitis.  

Similar to facial demodicosis, rosacea can present with erythema, papules, and pustules on the face. Patients with rosacea also have a higher prevalence and degree of Demodex mite infestation.⁴ However, these facial rashes can be differentiated when symptom acuity and personal and family histories are considered. In patients with a long-standing personal and/or family history of erythema, papules, and pustules, the chronicity of disease implies a diagnosis of rosacea. The acute onset of symptomatology and absence of personal or family history of rosacea in our patient favored a diagnosis of demodicosis. 

Pityrosporum folliculitis is an eruption caused by Malassezia furfur, the organism implicated in tinea versicolor. It can present similarly to Demodex folliculitis with follicular papules and pustules on the forehead and back. Features that help to differentiate Pityrosporum folliculitis from Demodex folliculitis include involvement of the upper trunk and onset after antibiotic usage.⁵ Diagnosis of Pityrosporum folliculitis can be confirmed by potassium hydroxide preparation, which demonstrates spaghetti-and-meatball-like hyphae and spores. 

Eosinophilic folliculitis is a chronic sterile folliculitis that usually presents as intensely pruritic papules and pustules on the face with an eruptive onset. There are 3 variants of disease: the classic form (also known as Ofuji disease), immunosuppression-associated disease, and infancy-associated disease.⁶ Eosinophilic folliculitis also may present with annular plaques and peripheral blood eosinophilia, and it is more prevalent in patients of Japanese descent. Differentiation from Demodex folliculitis can be done by histologic examination, which demonstrates spongiosis with exocytosis of eosinophils into the epithelium and a clear deficiency of infiltrating mites.⁶ 

Miliaria, also known as sweat rash, is a common condition that occurs due to occlusion of eccrine sweat glands.⁷ Clinically, miliaria is characterized by erythematous papules ranging from 2 to 4 mm in size that may be vesicular or pustular. Miliaria and demodicosis may have similar clinical presentations; however, several characteristic differences can be noted. Based on the pathophysiology, miliaria will not be folliculocentric, which differs from demodicosis. Additionally, miliaria most commonly occurs in areas of occlusion, such as in skin folds or on the trunk under tight clothing. Miliaria rarely can appear confluent and sunburnlike.⁸ Furthermore, miliaria is less common on the face, while demodicosis almost exclusively is found on the face. 

We present the case of an otherwise healthy patient with acute onset of pruritic papules and pustules involving the superior face following topical corticosteroid use. Similar cases frequently are encountered by dermatologists and require broad differential diagnoses. 

The Diagnosis: Demodicosis 

A clinical diagnosis of facial demodicosis triggered by topical corticosteroid therapy was suspected in our patient. A 3-mm punch biopsy of the right forehead demonstrated a follicular infundibulum rich in Demodex folliculorum with a discrete mononuclear infiltrate in the dermis (Figure 1), confirming the diagnosis. The patient was prescribed metronidazole gel 2% twice daily. Complete clearance of the facial rash was observed at 1-week follow-up (Figure 2). 

Demodex folliculorum is a mite that parasitizes the pilosebaceous follicles of human skin, becoming pathogenic with excessive colonization.^1-3 Facial demodicosis presents as pruritic papules and pustules in a pilosebaceous distribution on the face.^2,3 The diagnosis of facial demodicosis can be difficult due to similarities with many other common facial rashes such as acne, rosacea, contact dermatitis, and folliculitis.  

Similar to facial demodicosis, rosacea can present with erythema, papules, and pustules on the face. Patients with rosacea also have a higher prevalence and degree of Demodex mite infestation.⁴ However, these facial rashes can be differentiated when symptom acuity and personal and family histories are considered. In patients with a long-standing personal and/or family history of erythema, papules, and pustules, the chronicity of disease implies a diagnosis of rosacea. The acute onset of symptomatology and absence of personal or family history of rosacea in our patient favored a diagnosis of demodicosis. 

Pityrosporum folliculitis is an eruption caused by Malassezia furfur, the organism implicated in tinea versicolor. It can present similarly to Demodex folliculitis with follicular papules and pustules on the forehead and back. Features that help to differentiate Pityrosporum folliculitis from Demodex folliculitis include involvement of the upper trunk and onset after antibiotic usage.⁵ Diagnosis of Pityrosporum folliculitis can be confirmed by potassium hydroxide preparation, which demonstrates spaghetti-and-meatball-like hyphae and spores. 

Eosinophilic folliculitis is a chronic sterile folliculitis that usually presents as intensely pruritic papules and pustules on the face with an eruptive onset. There are 3 variants of disease: the classic form (also known as Ofuji disease), immunosuppression-associated disease, and infancy-associated disease.⁶ Eosinophilic folliculitis also may present with annular plaques and peripheral blood eosinophilia, and it is more prevalent in patients of Japanese descent. Differentiation from Demodex folliculitis can be done by histologic examination, which demonstrates spongiosis with exocytosis of eosinophils into the epithelium and a clear deficiency of infiltrating mites.⁶ 

Miliaria, also known as sweat rash, is a common condition that occurs due to occlusion of eccrine sweat glands.⁷ Clinically, miliaria is characterized by erythematous papules ranging from 2 to 4 mm in size that may be vesicular or pustular. Miliaria and demodicosis may have similar clinical presentations; however, several characteristic differences can be noted. Based on the pathophysiology, miliaria will not be folliculocentric, which differs from demodicosis. Additionally, miliaria most commonly occurs in areas of occlusion, such as in skin folds or on the trunk under tight clothing. Miliaria rarely can appear confluent and sunburnlike.⁸ Furthermore, miliaria is less common on the face, while demodicosis almost exclusively is found on the face. 

We present the case of an otherwise healthy patient with acute onset of pruritic papules and pustules involving the superior face following topical corticosteroid use. Similar cases frequently are encountered by dermatologists and require broad differential diagnoses. 

The Diagnosis: Demodicosis 

A clinical diagnosis of facial demodicosis triggered by topical corticosteroid therapy was suspected in our patient. A 3-mm punch biopsy of the right forehead demonstrated a follicular infundibulum rich in Demodex folliculorum with a discrete mononuclear infiltrate in the dermis (Figure 1), confirming the diagnosis. The patient was prescribed metronidazole gel 2% twice daily. Complete clearance of the facial rash was observed at 1-week follow-up (Figure 2). 

Demodex folliculorum is a mite that parasitizes the pilosebaceous follicles of human skin, becoming pathogenic with excessive colonization.^1-3 Facial demodicosis presents as pruritic papules and pustules in a pilosebaceous distribution on the face.^2,3 The diagnosis of facial demodicosis can be difficult due to similarities with many other common facial rashes such as acne, rosacea, contact dermatitis, and folliculitis.  

Similar to facial demodicosis, rosacea can present with erythema, papules, and pustules on the face. Patients with rosacea also have a higher prevalence and degree of Demodex mite infestation.⁴ However, these facial rashes can be differentiated when symptom acuity and personal and family histories are considered. In patients with a long-standing personal and/or family history of erythema, papules, and pustules, the chronicity of disease implies a diagnosis of rosacea. The acute onset of symptomatology and absence of personal or family history of rosacea in our patient favored a diagnosis of demodicosis. 

Pityrosporum folliculitis is an eruption caused by Malassezia furfur, the organism implicated in tinea versicolor. It can present similarly to Demodex folliculitis with follicular papules and pustules on the forehead and back. Features that help to differentiate Pityrosporum folliculitis from Demodex folliculitis include involvement of the upper trunk and onset after antibiotic usage.⁵ Diagnosis of Pityrosporum folliculitis can be confirmed by potassium hydroxide preparation, which demonstrates spaghetti-and-meatball-like hyphae and spores. 

Eosinophilic folliculitis is a chronic sterile folliculitis that usually presents as intensely pruritic papules and pustules on the face with an eruptive onset. There are 3 variants of disease: the classic form (also known as Ofuji disease), immunosuppression-associated disease, and infancy-associated disease.⁶ Eosinophilic folliculitis also may present with annular plaques and peripheral blood eosinophilia, and it is more prevalent in patients of Japanese descent. Differentiation from Demodex folliculitis can be done by histologic examination, which demonstrates spongiosis with exocytosis of eosinophils into the epithelium and a clear deficiency of infiltrating mites.⁶ 

Miliaria, also known as sweat rash, is a common condition that occurs due to occlusion of eccrine sweat glands.⁷ Clinically, miliaria is characterized by erythematous papules ranging from 2 to 4 mm in size that may be vesicular or pustular. Miliaria and demodicosis may have similar clinical presentations; however, several characteristic differences can be noted. Based on the pathophysiology, miliaria will not be folliculocentric, which differs from demodicosis. Additionally, miliaria most commonly occurs in areas of occlusion, such as in skin folds or on the trunk under tight clothing. Miliaria rarely can appear confluent and sunburnlike.⁸ Furthermore, miliaria is less common on the face, while demodicosis almost exclusively is found on the face. 

We present the case of an otherwise healthy patient with acute onset of pruritic papules and pustules involving the superior face following topical corticosteroid use. Similar cases frequently are encountered by dermatologists and require broad differential diagnoses.