Flat colonic adenomas in Malaysia: fact or fancy?

Non-polypoid colorectal neoplasms are relatively common worldwide

Flat adenomas are found commonly at colonoscopy throughout the world. Similarly, small, flat submucosally invasive cancers have been described worldwide but are relatively rare, accounting for 5% to 10% of all cancers detected at colonoscopy. Although there appears to be no difference in frequency of non-polypoid colorectal neoplasms between East and West, considerable variation has been reported by individual studies, probably because of lack of consistency when defining a flat lesion. Flat elevated lesions are the most common type of flat lesion and do not appear to have a greatly increased risk of harboring invasive malignancy; however, flat lesions with depression have a significant risk of malignancy and are probably the precursor lesions for most small, flat, or ulcerating cancers.

Flat adenomas of the large bowel: a single endoscopist study

PURPOSE

Flat colorectal adenomas may not be recognized or they may be seen and dismissed as normal mucosa. As a result, the "true" incidence of flat lesions is unknown. The aim of this study was to report the incidence and character of flat adenomas in a large series of patients in the United States.

METHODS

Details of colorectal polyps seen during colonoscopy are entered into a prospective database that was queried for flat adenomas. No magnification or dye spray was used. The colonoscopy completion rate was 96.8 percent. The flat adenoma detection rate of the senior author is in line with that of Japanese colonoscopists.

RESULTS

During 2,659 colonoscopies, 5,749 colorectal lesions were seen in 2,003 patients. Of these patients, 1,125 were men and 878 were women, with a mean age of 65 years (+/- 12 years). There were 3,115 adenomas (54 percent of lesions); 315 were flat (10.1 percent), 23 (0.8 percent) were depressed, 2,575 were sessile (82.7 percent), and 200 were pedunculated (6.4 percent). Two hundred twelve patients had flat adenomas (10.6 percent of patients); 172 patients had one and 40 had multiple (2 to 8) flat adenomas. Eight patients with flat adenomas had more flat adenomas on follow-up.

CONCLUSIONS

Colonoscopists in the United States must be aware of the existence of flat adenomas and sensitive to their appearance.

Chromoendoscopy of the colon

Chromoendoscopy is a technique that uses tissue stains to better characterize, delineate, or highlight the gastrointestinal mucosa. Chromoendoscopy of the colon has the potential to significantly aid the endoscopist in the recognition and identification of mucosal abnormalities ranging from inflammation to neoplasia.