[Proliferating trichilemmal tumor]

The proliferating trichilemmal tumor is a rare benign neoplasm of the outer roof sheath of the terminal hair follicle. It occurs almost exclusively in elderly women as a solitary tumor of the hairy scalp. In a woman 71 years of age a proliferating trichilemmal tumor developed during two years. A large cornu cutaneum of the parietal scalp was present. The clinical and histopathologic features can be mistaken for squamous cell carcinoma.