A case of verrucous-keratotic malignant melanoma

Abstract

We report a 49-year-old man with verrucous-keratotic malignant melanoma on his left forearm. The nodular tumor was uniformly black-colored, well circumscribed, and slightly elevated in a plateau with a warty and keratotic surface. Histopathologically, epitheloid atypical melanocytes, which formed irregular nests, were distributed from the upper part of the epidermis to the reticular dermis. The epidermis showed hyperkeratosis with papillomatous changes. The prominent clinical and histological verrucous features of this melanoma should be differentially diagnosed from other pigmented tumors such as seborrheic keratosis or basal cell carcinoma. Potential misdiagnosis of verrucous melanoma should be kept in mind. [Skin Cancer (Japan) 2005; 20: 296-300]