Snapshot A 23-year-old man presents with problems involving his teeth, bones, and vision. There is a family history of tumors of the thyroid and adrenal glands. Clinical evaluation reveals supernumerary teeth, long-bone osteomas, and increased retinal pigmentation. Introduction Subtype of familial adenomatous polyposis (FAP) FAP plus bony and soft tissue tumors osteomas desmoid tumors congenital hypertrophy of retinal pigment epithelium cutaneous lesions adrenal adenomas nasal angiofibromas Genetics autosomal dominant arises from same mutations as FAP inactivating mutation in APC (adenomatous polyposis coli) gene Presentation Symptoms/physical exam hundreds to thousands of adematous polyps in colon increased (inevitable) risk of colon cancer dental abnormalities supernumerary teeth osteomas of mandible, skull, and long bones cutaneous lesions epidermal cysts, fibromas, and lipomas desmoid tumors most commonly on abdomen plaques does not metastasize, but does invade in adjacent structures congenital hypertrophy of retinal pigment epithelium patches of pigmented lesions on ocular fundus predicts FAP with 42% sensitivity and 97% specificity Evaluation Based on endoscopy for polyposis, clinical exam, family history, and genetic testing Endoscopy > 100 colorectal adenomatous polyps Genetic testing APC mutation Radiography opaque lesions in bone Differential Diagnosis Peutz-Jegher syndrome Lynch syndrome Treatment Prophylactic colectomy as in FAP Routine screening for extracolonic tumors CT every 3 years Prognosis, Prevention, and Complications Prognosis almost normal with colonic screening and colectomy Complications untreated growth of desmoid tumors most common cause of mortality after colectomy is done invasion into vessels, nerves, bowel, etc