Solitary oral epidermolytic acanthoma: Case report of a rarely diagnosed entity.

Epidermolytic acanthoma represents a rare localized form of epidermolytic hyperkeratosis, which resembles warty lesions and shows a strong predilection for the genital skin of males. Here, we present an oral solitary epidermolytic acanthoma affecting a 71-year-old Caucasian man. Clinically, the lesion was white, well-circumscribed, and sessile, measuring 2 mm in diameter and located on the posterior mandibular buccal gingiva. Microscopically, pronounced hyperkeratosis and acanthosis, with formation of keratin crypts was observed. Lesional cells of the spinous and granular epithelial layers exhibited prominent intracellular vacuolar degeneration, as well as eosinophilic paranuclear and perinuclear condensations. Intracytoplasmic eosinophilic globules were also seen. No recurrences have been reported. Investigation for low- and high-risk human papillomavirus (HPV) infection failed to reveal positivity for HPV subtypes 6, 11, 16, and 18. Literature review revealed scarce reports of epidermolytic hyperkeratosis-like changes of the oral mucosa associated with malignant neoplasms and inflammatory processes. Epidermolytic acanthoma should be considered in the differential diagnosis of benign epithelial papillomatous lesions of the oral cavity.

Solitary epidermolytic acanthoma.

BACKGROUND: Solitary epidermolytic acanthoma is thought to be an uncommon lesion. It can present as a solitary, localized or disseminated process that is unrelated to the genetic form of icthyosis. METHODS: A retrospective review of solitary epidermolytic acanthomas was performed at the Ackerman Academy of Dermatopathology, NY, over a 2 year period. The clinical and histopathological features of solitary epidermolytic acanthomas were described in 64 biopsies from 60 individuals. In situ hybridization for human papillomavirus (HPV) was performed on all genital lesions. RESULTS: The incidence of epidermolytic acanthomas in our series was higher than previously reported (27.8/100,000). Genital location was the most common and the incidence of genital lesions was 8/100,000. In situ hybridization showed no evidence of genital HPV types within the lesions. The histological features of solitary epidermolytic acanthoma were re-evaluated. CONCLUSIONS: Genital skin was the most common location for solitary epidermolytic acanthoma, but we found no evidence to suggest a role for genital HPV types. A strong male predominance was noted, and the lesions demonstrate a wide range of clinical and pathological findings.

From hidroacanthoma simplex to poroid hidradenoma: clinicopathologic and immunohistochemic study of poroid neoplasms and reappraisal of their histogenesis.

BACKGROUND: Poroid neoplasms comprise classic poroma (P), hidroacanthoma simplex (HS), dermal duct tumor (DDT), and poroid hidradenoma (PH). The 3 latter are rarely reported. Poroid cells in P have recently been identified as keratinocytes of the lowermost acrosyringium and the sweat duct ridge. OBJECTIVES: To investigate a large cohort of poroid neoplasms to better define the clinical and pathologic aspects of HS, DDT, and PH. To analyze the expression of discriminatory keratins in all 4 poroid neoplasms. METHODS: 202 P, 11 HS, 17 DDT, 31 PH, and 5 composite tumors were examined under light microscopy, and 11, 9, 10, 15, and 2, respectively, by immunohistochemistry using anti-keratin antibodies, in particular, anti-K77, specific for luminal cells of the eccrine dermal sweat duct, and Ki-67 antibody. RESULTS: HS appeared later in life (66.6 years old) than P, DDT, and PH. Whereas P, DDT, and PH displayed unspecific clinical aspects, HS had most frequently the aspect of a large seborrheic keratosis with well-defined borders. HS, DDT, and PH were absent on palms and soles, but were found on the trunk, the lower limbs, and the upper limbs. Similar pathologic features were observed in all tumors, that is, a majority of poroid cells expressing K14, islands of K10-positive and K77-negative large cells. K77 expression was limited to luminal cells of intact ductal structures within the tumors. CONCLUSIONS: Our data demonstrate the common histogenesis of the 4 poroid neoplasms, which seem to derive from the basal keratinocytes of the sweat duct ridge and the lower acrosyringium. The variable length of the sweat duct ridge may account for the variety of poroid neoplasms, according to the site of tumor induction along this structure.

Solitary and multifocal oral melanoacanthoma.

BACKGROUND: Oral melanoacanthoma is a rare pigmented lesion characterized by sudden appearance and rapid radial growth, mimicking malignant melanoma. Oral melanoacanthoma may present as a solitary or multifocal lesion; however, the characteristics of these two clinical variants have never been addressed. In this study, we present an unusual case of multifocal oral melanoacanthoma and analyze cases of oral melanoacanthoma reported in the literature, with special emphasis on multifocal lesions. METHODS: A thorough MEDLINE search of the literature for cases of oral melanoacanthoma was performed. The demographic and clinical data, histologic features, and immunohistochemical findings were extracted from the full-text articles. RESULTS: The literature search yielded 52 patients with 67 lesions. The addition of our case increased this number to 53 patients with 72 lesions, 43 of whom had solitary lesions and 10 of whom had multifocal lesions. There was a female predominance amongst the patients with solitary oral melanoacanthoma (3 : 1), whereas multifocal oral melanoacanthoma showed an equal gender distribution (1 : 1). Multifocal lesions tended to occur more frequently on the palate, and solitary lesions on the buccal mucosa. CONCLUSIONS: Multifocal oral melanoacanthoma appears to demonstrate some demographic and clinical variations from the solitary type of lesion.