Endoscopic discrimination of sessile serrated adenomas from other serrated lesions

Sessile serrated adenoma (SSA) is a proposed precursor of colorectal carcinogenesis. This study aimed to analyze the potential of endoscopy to discriminate SSA from other serrated lesions, specifically traditional serrated adenoma (TSA) and hyperplastic polyp (HP). Of 145 serrated lesions, 111 sessile serrated lesions including 32 TSAs, 25 SSAs and 54 HPs were analyzed for size, color, location and morphologic features using conventional endoscopy and magnifying chromoendoscopy. SSA was preferentially located in the right colon, whereas TSA and HP were located in the left colon. The sizes of SSA and TSA were larger than those of HP. The lesion color was indistinguishable among TSA, SSA and HP. Macroscopically, a pinecone-like or two-tier raised appearance were found more frequently in TSA than in SAA and HP. Under magnified chromoendoscopic observation, the stellar III(L) pit pattern and fern-like appearance were observed more frequently in TSA than in SAA and HP. In conclusion, endoscopic discrimination between SSA and other sessile serrated lesions based on morphological features was difficult. However, size and location of the lesions facilitated diagnosis.