A rare disease that is common among those with Familial Adenomatous Polyposis that creates noncancerous growth in the connective tissues that provide strength and flexibility to structures such as bones, ligaments, and muscles. These tumors can develop anywhere in the body although most often are found in the abdomen, arms and legs. Desmoids can grow into nerves or blood vessels and exert pressure on other organs. Also known as aggressive fibromatosis.