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.