colon polypGastroenterology A hereditary or acquired pedunculated neoplasm arising from the colonic mucosa; small CPs are usually benign, but may become malignant; like colorectal CA, CPs may present with occult bleeding. See Polyp, Colorectal cancer.
Acquired polyps Adenomatous or tubular–villous in morphology, ↑ frequency with age; although often asymptomatic, larger polyps are often announced by bleeding or changed bowel habits; if very large, APs may form a leading 'front' of an intussusception; distinction between adenomatous polyps–'tight' round glands and villous adenomas–finger-like fronds of elongated glands has little practical importance–both have malignant potential; periodic colonoscopy and polypectomy yields a 3-fold ↑ in subsequent cancer; hyperplastic polyps are also acquired but are non-neoplastic
• Familial adenomatous polyposis A premalignant, AD condition presenting in early adulthood with 100s to 1000s of colonic polyps, related to a loss of the normal repression of DNA synthesis in the entire colonic epithelium; adenocarcinoma occurs in 70–100% of Pts, prevented by prophylactic colectomy
• Gardner syndrome A rare AD condition with premalignant polyps of the entire GI tract, which is identical to FAP, but has, in addition, extraintestinal tumors; most Pts develop colon carcinoma; other neoplasms in GS Pts include bile duct carcinoma, osteomas of mandible, skull, and long bones, soft tissue tumors–fibromas, lipomas, sebaceous cysts, and rarely, thyroid and adrenal gland cancers