Linear psoriasis.

A 33-year-old man presented with verrucous, red-brown papules, which coalesced into linear plaques on the right buttock, waist, thigh, and genitals. A skin biopsy was consistent with psoriasis, and the unilateral distribution in a linear pattern led to a diagnosis of linear psoriasis, which is a rare variant of psoriasis. Although histopathologically it can be difficult to distinguish from inflammatory linear verrucous epidermal nevus (ILVEN), linear psoriasis presents in adulthood and responds to conventional topical antipsoriatic therapies.

Fixed cutaneous sporotrichosis.

Sporotrichosis is a subcutaneous mycosis that is caused by Sporothrix schenckii. Whereas the most common clinical presentation is the lymphocutaneous form, the fixed cutaneous form is not uncommon. Important clues from the clinical history, such as travel and occupation, can help to raise the suspicion of this infection in the differential diagnosis. However, histopathologic and tissue culture, which often require multiple specimens, are necessary to confirm the diagnosis. We present a patient with fixed cutaneous sporotrichosis whose delayed diagnosis led to appreciable scars and morbidity.

Cutaneous piloleiomyomata.

A 49-year-old man presented with an eight-month history of intermittently painful, subcutaneous nodules that were increasing in size, number, and pain intensity. A biopsy specimen showed smooth muscle proliferation, which also stained positive for actin, and was consistent with piloleiomyoma. The patient was placed initially on gabapentin and then nifedipine with very limited success in pain control. The lesions continued to proliferate, and the patient was referred to surgery for excision.

ILVEN-like persistent psoriasiform dermatitis confined to a congenital Becker nevus.

A 10-year-old boy presented with a 5-year history of an intractably pruritic, recalcitrant psoriasiform plaque in a broad vertical band on the left buttock, with histologic as well as clinical features suggestive of an inflammatory linear verrucous epidermal nevus. This lesion was completely superimposed upon a congenital Becker nevus. We postulate that the restricted distribution and persistence of the psoriasiform plaque reflected an inflammatory response limited to the aberrant clone of cells composing the Becker nevus, a manifestation of cutaneous mosaicism that could be characterized as an "inflammatory Becker nevus."

Cutaneous Rosai-Dorfman disease.

A 63-year-old woman developed multiple nodules at the site of a recently biopsied proliferation of CD 68+ histiocytes. Clinical lymphadenopathy was not present on physical examinaton or on computed tomography scans. A subsequent skin biopsy specimen showed changes consistent with Rosai-Dorfman disease. Rosai-Dorfman disease is a benign, histiocytic proliferative disorder also known as sinus histiocytosis with massive lymphadenopthy. A particularly rare, extranodal, purely cutaneous form has been described. Spontaneous regression tends to occur over months to years, with surgical intervention remaining the most effective treatment. Documented success with a number of other therapies has been reported, which include systemic high-dose thalidomide in extensive cutaneous disease.

Unilateral nevoid telangiectasia.

A 30-year-old woman, who was six months pregnant, presented with multiple, blanching, asymptomatic telangiectasies on her right upper extremity for two years. At the onset of her pregnancy, her lesions increased in number and redness. Given the unilateral distribution and worsening during pregnancy, a diagnosis of unilateral nevoid telangiectasia was made. This condition is a rare entity that has been most commonly reported in association with puberty, pregnancy, the use of oral contraceptives, and alcoholic cirrhosis. However, there have been case reports in otherwise healthy individuals.

Extramammary Paget disease.

A 59-year-old man presented with a well-demarcated, tender ulcer at the base of the penile shaft that had been present for approximately five years. The ulcer had been responsive neither to topical antibacterials, antifungals, and glucocorticoids nor to oral acyclovir. A biopsy specimen showed an intra-epidermal neoplasm consistent with extramammary Paget disease (EMPD) based on light microscopy and immunohistochemistry. Patients with EMPD require extensive medical evaluation because of its association with adnexal carcinoma and visceral malignant conditions. Evaluation should include a full body skin and lymph node examination, colonscopy, cystoscopy, and sex-specific studies including pelvic and breast examinations, with imaging for women and prostate examination with prostate specific antigen levels for men. Close monitoring after treatment is important because of the recognized risk of recurrence and malignant conditions.

Clear cell papulosis.

A 2-year-old boy presented with multiple, hypopigmented, flat-topped papules in the pubic region and on the abdomen in a distribution pattern that followed the milk lines. The lesions had first appeared at age three months and increased in number over time. Histopathologic examination showed large clear cells within the lower epidermis, which stained positively with periodic acid-Schiff. These findings were diagnostic of clear cell papulosis, a rare condition that primarily affects young children. We review the histopathologic and immunohistochemical findings that link clear cell papulosis to clear cells of Toker and extramammary Paget disease.

Eruptive xanthomas.

A 26-year-old woman presented for evaluation of multiple, red-yellow papules that had been appearing over the course of 2 months on the extensor surfaces of the upper extremities, dorsal aspects of the hands, thighs, and buttocks. Serum lipid evaluation showed hypertriglyceridemia in a patient with a recent history of pancreatitis. A diagnosis of eruptive xanthomas was made based on clinical, laboratory, and histopathologic findings.

Pseudolymphoma evolving into diffuse large B-cell lymphoma.

A 46-year-old man presented with a 1-year history of asymptomatic papules on the right arm, without an antecedent event. Initial clinical and histopathologic features were consistent with a pseudolymphoma without gene rearrangements, and the patient was treated with intralesional glucocorticoids. Four months later, the patient developed additional papules and plaques on the right arm, and, at this time, clinical and histopathologic features were most consistent with a T-cell-rich, large B-cell lymphoma, with monoclonal immunoglobulin light chain gene rearrangement. Systemic evaluation showed no evidence of extracutaneous involvement. The transformation of a pseudolymphoma into a large B-cell lymphoma is a rare event. This patient's subtype, diffuse large B-cell lymphoma-other, carries an intermediate prognosis when compared to the more aggressive leg subtype and more indolent folliculocentric subtype. Potential therapeutic options include local radiotherapy, chemotherapy, and rituximab.

Epidermodysplasia verruciformis in the setting of HIV infection.

A 56-year-old man with human immunodeficiency virus infection presented with pink-to-hypopigmented, thin, flat-topped papules coalescent to plaques on the trunk and extremities for five years. The histopathologic findings were consistent with flat warts resembling epidermodysplasia verruciformis. Typically an inherited condition, this entity has also been observed in the setting of immunosuppression; the risk of developing non-melanoma skin cancers is of concern. Treatment options vary considerably, but often the lesions will recur upon cessation of therapy.

Steroid-responsive facial eruption with cornoid lamellae--a possible new entity.

The histopathologic presence of a cornoid lamella is often associated with a diagnosis of porokeratosis. However, this feature is not pathognomonic for porokeratosis and can be found in a number of other dermatologic conditions, which include seborrheic keratosis, verruca vulgaris, actinic keratosis, squamous-cell carcinoma in situ, basal-cell carcinoma, milia, and scar. Notably, the etiology of none of these entities is inflammatory. Wade and Ackerman consider cornoid lamellation to be a distinctive histopathologic reaction pattern that reflects the disordered progression of epidermal cells during cornification. As such, this pattern is not specific for any given disease process. We report a case in which the lesions appeared inflammatory clinically as well as histopathologically, did not resemble porokeratosis despite the presence of cornoid lamellae, and responded to topical glucocorticoids.

Chronic cutaneous lupus erythematosus in vitiligo.

A 49-year-old woman presented with a seven-year history of pruritic, erythematous, scaling plaques on sun-exposed skin that localized only to pre-existing depigmented patches. Histopathologic examination showed changes consistent with cutaneous lupus erythematosus with lichenoid features and confirmed contiguous vitiligo. Diagnosis of chronic cutaneous lupus erythematosus localized to areas of vitiligo was determined by clinicopathologic correlation and may reflect an autoimmune diathesis. Consequently, hydroxychloroquine and topical glucocorticoids therapy were initiated with reported improvement in pruritus, erythema, and scale. Clinical monitoring for development of squamous-cell carcinoma in areas of chronic inflammation and sun-exposure is imperative.

Erythema elevatum diutinum.

A 64-year-old woman presented with a one-and-one-half year history of an enlarging, red-brown, firm plaque on the left thigh, with numerous, scattered, indurated, hyperpigmented patches on the lower extremities. Histopathologic examination of the largest plaque confirmed the diagnosis of erythema elevatum diutinum, which is a rare form of leukocytoclastic vasculitis that is associated with many disease entities, which include human immunodeficiency virus infection, malignant conditions, hematologic abnormalities, chronic infection, and autoimmune and connective-tissue disorders. The treatment of choice is dapsone; however, several other treatment modalities have been reported to be of benefit.

Cutaneous umbilical endometriosis.

A 35-year-old woman presented with a four-month history of a tender umbilical nodule that bleeds during her menstrual period. Physical examination showed a hyperpigmented umbilical nodule. A biopsy specimen showed fibrotic dermis with increased numbers of blood vessels and scattered glandular structures with areas of hemosiderin deposition consistent with a diagnosis of endometriosis. Cutaneous umbilical endometriosis is rare, with an estimated incidence of 0.5 to 1.0 percent. Although anti-gonadotropin medications, such as danazol, have been used for symptomatic control, but surgical excision is the treatment of choice owing to the possibility of malignant degeneration of cutaneous endometriosis.

Invasive squamous-cell carcinoma and arsenical keratoses.

A 42-year-old man presented with a six-month history of a slowly-enlarging ulcer on his right sole, a 30-year history of altered pigmentation of the trunk and extremities, and hyperkeratotic papules of the palms and soles. Histopathologic examination showed an invasive squamous-cell carcinoma of the right sole and hyperkeratosis with keratinocyte atypia of the left finger and left lateral foot. The clinical and histopathologic findings are consistent with chronic arsenicism, which most commonly occurs in the setting of drinking contaminated water or after occupational exposure. Evaluation should include a physical examination, basic laboratory work-up, and measurement of a 24-hour urine arsenic concentration. Vigilant surveillance for the development of cutaneous malignancies is required. Oral retinoids may be helpful in reducing hyperkeratosis secondary to chronic arsenicism.

Pretibial epidermolysis bullosa.

A 47-year-old Vietnamese woman presented with dystrophic fingernails and toenails that had been present since infancy. She also had developed, in the third decade, pretibial pruritus with vesicle formation and progressive localized papules and scars. Multiple family members were similarly affected. Physical examination showed lichenoid papules that coalesced into large plaques that were studded with milia over the pretibial areas and 20 nail dystrophy. A biopsy specimen showed milia-like structures and dermal fibrosis. Pretibial epidermolysis bullosa is a rare variant of dystrophic epidermolysis bullosa that shows appreciable clinical overlap with dystrophic epidermolysis bullosa pruginosa. Both disease subsets are characterized by the late age of onset, nail dystrophy, and predominantly pretibial pruritic lichenoid skin lesion; they are associated with glycine substitution mutations in COL7A1.