A fatal case of carcinoma arising from a pilonidal sinus tract.

We report a male patient with carcinoma arising on the basis of neglected sacrococcygeal pilonidal sinus disease. Following initial operation, performed without suspicion of malignancy, histology demonstrated cellular atypia and an increased mitotic rate. A second, wider tissue excision was recommended but the patient declined further surgery. Two years later, he presented with fungating carcinoma involving the rectum but again declined surgery. This rare case demonstrates that the presence of carcinoma should be suspected in long-standing, although innocent-looking, pilonidal sinus disease. In the circumstance of uncertain histologic diagnosis, more generous surgical sampling is required. Every effort must be made to overcome patient's reluctance to accept a second, possibly life-saving procedure.