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Endoscopic Features of Sessile Serrated Polyps Identified

Summary and Comment |
July 2, 2013

Endoscopic Features of Sessile Serrated Polyps Identified

  1. Douglas K. Rex, MDAU061

With use of white-light endoscopy, identification of both indistinct borders and a “cloud-like” surface resulted in diagnostic accuracy of 93%.

  1. Douglas K. Rex, MDAU061

The serrated class of colorectal polyps (vs. conventional adenoma class) includes sessile serrated polyp (SSP) or adenoma, hyperplastic polyp, and traditional serrated adenoma. The SSP is both common (unlike the traditional serrated adenoma) and, based on its molecular features and observational study findings, seems to be the main precursor of hyper-methylated colorectal cancers. Hyperplastic polyps, conversely, are not generally considered precancerous.

In general, evidence is lacking on whether endoscopists can differentiate hyperplastic polyps from SSPs during real-time colonoscopy. The latter tend to be larger and distributed more toward the proximal colon. A recent Japanese study using high-magnification colonoscopes (not generally available in the U.S.) found that large circular pits, designated “type O” pits, are very specific, though not sensitive, for SSPs. Histological changes indicative of SSPs are generally located in the base of the crypts, possibly confined to one or a few crypts, theoretically making them invisible to an endoscopist inspecting the surfaces of the pits during colonoscopy.

Now, an international group of experts has proposed white-light and narrow-band imaging (NBI) criteria for differentiation of SSPs from hyperplastic polyps as derived from a “learning set” of images and validated in a set of photographs of serrated lesions. From white-light images, two endoscopic features were highly associated with SSPs: indistinct borders and a “cloud-like” surface, referring to the bumpy texture change often seen in SSPs. From NBI images, four features were strongly associated with SSPs: the cloud-like surface, irregular shape, indistinct borders, and dark spots inside the crypts (which almost certainly correspond to the type O pits described in the Japanese study). In the validation set of 300 photographed polyps, 69% were considered of adequate quality for assessment by white-light and 39% by NBI. In this subset, sensitivity, specificity and overall accuracy were 75%, 79%, and 77%, respectively, for white-light and 89%, 96%, and 93% for NBI.

Comment

Study limitations include the design and execution by experts only, reliance solely on photographs, and exclusion of nearly one third of photographs deemed low-quality. Nevertheless, the findings provide clear evidence that some endoscopic features are associated with sessile serrated polyps compared with hyperplastic polyps. These data might be valuable in helping endoscopists decide whether to resect and in gaining confidence to leave small, distal-colon, hyperplastic polyps in place. Additional study of this important issue is warranted.

  • Disclosures for Douglas K. Rex, MD at time of publication Consultant / Advisory board Exact Sciences; Ferring Pharmaceuticals; Given Imaging; Olympus Speaker’s bureau Boston Scientific; Braintree; Ferring Pharmaceuticals Grant / research support Battelle; Braintree; Northwestern University; Olympus America Editorial boards Annals of Gastroenterology and Hepatology; Comparative Effectiveness Research; Expert Review of Gastroenterology and Hepatology; Gastroenterology; Gastroenterology and Hepatology News; Gastroenterology Report; Gastroenterology Research and Practice; Journal of Clinical Gastroenterology; Techniques in Gastrointestinal Endoscopy; World Journal of Gastroenterology; World Journal of Gastrointestinal Oncology; World Journal of Gastrointestinal Pathophysiology; World Journal of Gastrointestinal Pharmacology and Therapeutics

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