Mesenteric fibromatosis in Gardner syndrome. This scanning view shows a dense fibroblastic lesion infiltrating the wall of small bowel. Gardner syndrome is an autosomal dominant disease and consists of a constellation of intestinal polyposis, osteomas, fibromas, and epidermal/sebaceous cysts. About 10% of patients with Gardner syndrome/FAP develop intra-abdominal fibromatosis. Interestingly, fibromatosis develops 1 to 2 years after colectomy is performed for intestinal polyposis.