Malignant proliferating trichilemmal tumor.

Proliferating trichilemmal tumor (PTT) is a benign tumor originating from the outer root sheath of a hair follicle. Malignant transformation in case of PTT is very rare and unusual finding. It is usually confused with squamous cell carcinoma both sharing many common features. So the identification of malignant PTT is very essential. Only 39 well-documented cases of malignant proliferating trichilemmal cyst have been published to date in the English language literature. We hereby present a case of a 75-year-old female patient with a rapidly growing swelling on the scalp.