Seborrheic keratosis: an acantholytic variant.

Two elderly women with seborrheic keratoses on the abdomen are reported on because of the peculiar histologic appearance characterized by prominent acantholysis. Although the basic histologic architecture was a papillomatous acanthoma corresponding to that of seborrheic keratosis, the upper portion of the lesions showed extensive acantholytic changes and dyskeratotic cells. Differentiation from seborrheic keratosis with focal acantholytic dyskeratosis, warty dyskeratoma, keratosis senilis and acantholytic squamous cell carcinoma could be made on the basis of clinical as well as histological features. Although the histogenesis is uncertain, it seems logical to propose that this is a rare variant of irritated seborrheic keratosis.