 The extracolonic tumors may include osteomas of the skull, thyroid cancer, epidermoid cysts, fibromas, as well as the occurrence of desmoid tumors in approximately 15% of affected individuals.Desmoid tumors are fibrous tumors that usually occur in the tissue covering the intestines and may be provoked by surgery to remove the colon.The countless polyps in the colon predispose to the development of colon cancer; if the colon is not removed, the chance of colon cancer is considered to be very significant.