Abstract

Subungual acantholytic dyskeratotic acanthoma in a 53-year-old male: A case report

Acantholytic dyskeratotic acanthoma (ADA) is a rare and benign epidermal tumor primarily found on the trunk as a solitary papule that can clinically mimic basal cell carcinoma. However, it has infrequently been reported in association with the nail unit showing distinct clinical features, with only seven cases reported in the literature. Here, we present the case of a 53-year-old male with subungual ADA, presenting on the left fifth thumbnail as a nontender, approximately 3 mm dark brown macule of the proximal nail, with an accompanying longitudinal ridge in the nail. The initial clinical impression was onychopapilloma, and nail bed and matrix longitudinal biopsy were performed after nail plate removal. Histologically, hematoxylin and eosin staining revealed serum in the nail plate, focal tiered parakeratosis associated with the nail plate, suprabasilar clefting, and keratinocyte acantholysis with mild focal dyskeratosis in the matrical epithelium. Immunostaining with MART-1 failed to highlight a significant melanocytic proliferation. Although histologic findings share some common features with pemphigus, warty dyskeratoma, Darier disease, and Hailey-Hailey disease; integration with clinical findings aids in reaching the final diagnosis. This case highlights the need for awareness of subungual ADA, as it can present with unique clinical features compared to ADA in other locations, and achieving a correct diagnosis requires correlation of clinical and pathological findings.