GI Radiology > Colon > Neoplasms > Polyps

Neoplasms

Polyps

Polyps are focal masses that protrude from the mucosa into the bowel lumen. There are many types of polyps. Hyperplastic polyps stem from mucosal proliferation and are round, sessile, non-neoplastic, and almost always less than 5mm. Adenomatous polyps are considered premalignant, are neoplasms with a center of connective tissue and a major risk for developing colorectal cancer. There are 3 types of adenomatous polyps: tubular, villous and tubulovillous, with villous having the highest potential for malignancy. Inflammatory polyps, though rare, are usually multiple in association with inflammatory bowel disease. Hamartomatous polyps (a.k.a. juvenile polyps) are a common cause of rectal bleeding in the pediatric population. In general, polyps less than 1cm in diameter have a 1% risk of cancer, 1-2cm have a 10% risk, and those greater than 2cm have up to a 50% risk. Thus, barium studies are often indicated to detect colon polyps. Radiographically, benign polyps are small in diameter, stable in growth, spherically shaped, have normal mucosa, long stalks, and a smooth surface. Malignant polyps on the other hand are large in diameter, sessile, irregularly shaped, may exhibit sudden growth, and have a broader base and puckered mucosa. Familial Adenomatous Polyposis Syndrome is an autosomal dominant disease characterized by the development of hundreds of tubulovillous adenomas by the age of 20. Nearly all patients will develop colorectal carcinoma so a total colectomy is highly recommended.

A polyp on plain film (arrow)

Adenomatous polyp on plain film (center)

 

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