Acantholytic Acanthoma Arising in Severely Photodamaged Skin: A Case Report

Acantholytic acanthoma is a rare benign epidermal tumor that usually occurs in elderly individuals as a solitary, asymptomatic, keratotic papule, most commonly located on the trunk. Histopathologically, it is characterized by hyperkeratosis, papillomatosis, acanthosis, and acantholysis at various levels of the epidermis. Although its exact etiology remains unclear, it has been suggested that acantholytic acanthoma may arise in association with immunosuppressive states or chronic UV-induced skin damage. We present a rare case of acantholytic acanthoma that developed on the face of a 73-year-old male patient with severely photodamaged skin and a history of multiple cutaneous malignancies. The patient presented with an asymptomatic, erythematous, 1.5 cm papule on the right cheek. His medical history included spindle-cell squamous cell carcinoma of the right auricular helix and infiltrative-type basal cell carcinoma of the right dorsal forearm. Dermoscopic examination of the lesion revealed white dots and telangiectasias on an erythematous background. Histopathologic evaluation of the punch biopsy specimen showed marked hyperkeratosis, papillomatosis, acanthosis, and intraepidermal acantholysis, findings consistent with acantholytic acanthoma. Complete surgical excision was performed, and no recurrence was observed during follow-up. Acantholytic acanthoma is most often found on the trunk, and facial localization is extremely uncommon. In our case, the lesion's occurrence in a patient with severe photodamage and a prior history of different skin cancers is noteworthy and may suggest a possible relationship between UV exposure and the development of acantholytic acanthoma. Histopathologically, it must be differentiated from other acantholytic dermatoses such as pemphigus vulgaris, Hailey-Hailey disease, and Grover's disease, as well as from acantholytic actinic keratosis and basal cell carcinoma. Acantholytic acanthoma is distinguished by its solitary presentation, benign clinical course, and absence of cellular atypia or dysplasia. Complete excision is curative, and recurrence is rare. This case contributes to the expanding clinical spectrum of acantholytic acanthoma by highlighting that it can develop on severely photodamaged skin. Moreover, it underscores the importance of considering acantholytic acanthoma in the differential diagnosis of solitary erythematous papular lesions on the face, especially in elderly individuals with chronic sun damage. Early recognition and appropriate management can ensure excellent outcomes and prevent unnecessary interventions.