Villous adenoma of the rectum usually presents with
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a. Adenomatous polyps are common, occurring in up to 25% of the population older than 50 years of age in the By definition, these lesions are dysplastic.
b. The risk of malignant degeneration is related to both the size and type of polyp.
c. Tubular adenomas are associated with malignancy in only 5% of cases, whereas villous adenomas may harbor cancer in up to 40%.
d. Tubulovillous adenomas are at intermediate risk (22%).
e. Invasive carcinomas are rare in polyps smaller than 1 cm; the incidence increases with size.
f. The risk of carcinoma in a polyp larger than 2 cm is 35 to 50%. Although most neoplastic polyps do not evolve to cancer, most colorectal cancers originate as a polyp.
g. Polyps may be pedunculated or sessile.
h. Most pedunculated polyps are amenable to colonoscopic snare excision.
i. Removal of sessile polyps is often more challenging. Special colonoscopic techniques, including saline lift and piecemeal snare excision, facilitate successful removal of many sessile polyps.
j. For rectal sessile polyps, transanal operative excision is preferred because it produces an intact, single pathology specimen that can be used to determine the need for further therapy.
k. The site of sessile polypectomies should be marked by injection of methylene blue or India ink to guide follow-up colonoscopy sessions to ensure that the polyp has been completely removed, and to facilitate identification of the involved bowel segment should operative resection be necessary.
l. Colectomy is reserved for cases in which colonoscopic removal is impossible, such as large, flat lesions or if a focus of invasive cancer is confirmed in the specimen.
m. These patients may be ideal candidates for laparoscopic colectomy.