Verrucous-keratotic variations of malignant melanoma: a clinicopathological study.

Verrucous-keratotic forms of malignant melanoma occur more commonly in women and favor the extremities, but may occur on any anatomic site. Seventy-one percent of such melanomas are situated on the upper and lower extremities. Although two-thirds of these neoplasms can be assigned a histologic pattern according to the classification of Clark, one-third of these melanomas with marked verrucous hyperplasia and hyperkeratosis of the epidermis do not fit into his classification. The neoplastic cells proliferate mostly at the dermo-epidermal interface rather than in the upper reaches of the epidermis. Nodules are practically never formed. Most of the neoplasms are elevated, but like plateaus. They usually show only sparse, mononuclear inflammatory-cell infiltration. Clinically, verrucous-keratotic melanomas resemble one another in that they are small, slightly elevated, devoid of nodules, and without areas of regression. The prognosis of verrucous-keratotic melanomas does not differ from that of nonverrucous melanomas matched for sex, anatomic site, and thickness of the neoplasm.