Occurrence of basal cell carcinoma among multiple trichoepitheliomas.

We describe four patients who developed basal cell carcinoma (BCC) among multiple facial trichoepitheliomas. The only clinical feature that distinguished the carcinomas from the trichoepitheliomas was their larger size in three of the four patients. None of the lesions ulcerated. Whether the BCCs developed independently or by transformation from a trichoepithelioma is uncertain. Mohs micrographic surgery was helpful in revealing the transition from one tumor type to the other so that as much normal tissue as possible could be saved. The literature on the relationship between multiple hereditary trichoepitheliomas and BCCs is reviewed.