A case of melanoacanthoma

Melanoacanthoma is a variant of seborrheic keratosis which was first introduced by Mishima and Pinkus in 1960. This is a very rare and benign, epidermal tumor. Clinically, it is usually manifested in a pigmented, verrucous, round or oval plaque and nodular lesion. This is characterized histologically by nonpigmented keratinocytes and numerous large, richly dendritic melanocytes. We describe a 68-year-old man who suffered from a black-colored plaque on his right shin for 5 years. Melanoacanthoma was diagnosed by characteristic histopathologic findings.