A corn is a circumscribed area of callus that has developed a hard central conical core. It is produced by intermittent pressure on the skin overlying a bony prominence. Its commonest location is on the outer side of the fifth toe, but it occurs frequently on the dorsa of the three middle toes, tip of the small toe, and on the soles. Corns may occur on portions of the body remote from the feet, such as the fingers of violinists and spin bowlers. A search of the medical literature since 1927 has failed, however, to reveal a report of an instance in which such lesions have appeared on the buttocks. Because of the rarity of corns at this site, the following case is reported briefly.
An epileptic mental defective has been a patient at the Pennhurst State School since the age of 2 years. At the time his lesions were