Small flat adenoma: important in colon carcinogenesis?

The risk for development of colonic carcinoma increases with increasing size of the polyp. Endoscopists have focused attention on large polyps. Small flat adenomas are sessile polyps that measure less than 1 cm; they are nearly flat, and they have a slight depression in the center. They have a high incidence of cancer in situ. Adenomatous polyps follow the adenoma-carcinoma sequence. Small flat adenomas do not appear to follow this sequence, but they may be precursors of so called de novo colonic carcinoma. The genetics of small flat adenomas are not fully elucidated. Small flat adenomas may not be identified during standard colonoscopy due to the small size of the lesion. Chromoendoscopy may increase the rate of detection.