A rare condition characterized by the development of multiple little tumors on various parts of the body that grow hair. The tumors originate mainly from the sweat and scent producing glands. The growths occur mainly on the scalp and neck. Tumors close together may merge and ulcerate or become infected. The tumors usually start after the first decade and continue to grow slowly in size and number. In rare severe cases, the cylindromas may be the size of fists. See also Ancell's syndrome