Proliferating trichilemmal tumor (PTT) is a rare distinctive lesion that usually occurs in the scalp of elderly women. About 40 cases of malignant PTTs have been reported. Alternatively, some authors have proposed that all PTT are squamous cell carcinomas. We report a case of a malignant PTT on the scalp in 44-year-old man. Clinical features and histological criteria for diagnosis of malignant versus benign PTT are discussed.