[Cutaneous horn. Inverted follicular keratosis with an underlying tricholemmoma]

A 54 year old woman with an asymptomatic small cutaneous horn on her chin for several years is reported. Histologically the lesion had the combined features of an inverted follicular keratosis on its upper part and a nodular intradermal trichilemmoma with central cystic degenerative changes underlying the inverted follicular keratosis exophytic one. The relationships between the two lesions is discussed as well as the main controversial histogenetic hypothesis.