Inverted follicular keratosis.

Inverted follicular keratosis, a benign tumor of the skin believed to arise from the infundibular portion of the hair follicle that can involve perioral skin, has a unique histologic picture. It can be confused with forms of skin cancer; with knowledge of this entity, oral and maxillofacial surgeons may be able to avoid unnecessary surgery. The clinical and microscopic findings of 12 cases of inverted follicular keratosis are reported.