Squamous-cell carcinoma of the pilonidal sinus: report of a case and review of the literature.

Squamous-cell cancer developing in chronic pilonidal sinuses is extremely rare. Thousands of pilonidal cysts and sinuses are operated upon each year, and malignancy is almost never encountered. Only 26 cases of malignancy arising in pilonidal sinuses are reported in the world literature. We report and document a squamous-cell cancer arising in a chronic pilonidal sinus and also review the world literature.