Carcinoma cuniculatum of the buttock. An unusual case with an inverted growth.

A rare case of carcinoma cuniculatum involving the buttock in a 56-year-old male is presented. This case is uncommon in that the tumor was largely subcutaneous, while the usual carcinoma cuniculatum is an exophytic growth. Although carcinoma cuniculatum has a wide clinical and histological spectrum, to our knowledge there has been only 1 case with similar histological features, located in a pilonidal sinus, and another case located on the buttock.