Warty dyskeratoma of the oral mucosa. Correlated light and electron microscopic study.

A warty dyskeratoma arising from the palatal mucosa of a 36-year-old man was studied by light and electron microscopy. The ultrastructural features of this lesion were compared with those of the lesions of Darier's disease. Histologic sections showed a keratin-filled depression of the epithelial surface, suprabasal clefting, and acantholytic, dyskeratotic grains and corps ronds. Electron microscopic examination revealed a decrease in the number of intact attachment sites on the surfaces of the epithelial cells adjacent to the suprabasal cleft. Acantholytic grains within the cleft contained dense bands of tonofilaments and were devoid of attachment sites. Corps ronds within the stratum granulosum appeared as dyskeratotic vacuolated cells. Warty dyskeratomas and the lesions of Darier's disease are clinically distinct, but the acantholytic and dyskeratotic cells characteristic of both show many ultrastructural similarities.