Distinct endoscopic characteristics of sessile serrated adenoma/polyp with and without dysplasia/carcinoma

Background and Aims: Sessile serrated adenoma/polyp (SSA/P) is a colorectal polyp that has malignant potential. However, the dysplastic components within an SSA/P can be difficult to detect. This study aimed to clarify the endoscopic characteristics of SSA/P with advanced histology. Methods: We examined 462 endoscopically or surgically resected lesions that were pathologically diagnosed as SSA/P, including 414 without and 41 with cytologic dysplasia, and 7 with invasive carcinoma. We retrospectively studied the clinicopathologic and endoscopic characteristics and performed pit pattern analysis. Results: A stepwise increase in the size of the SSA/P series was identified along with their dysplastic progression, although 19 of 48 (39.6%) SSA/Ps with dysplasia/carcinoma were <= 10 mm in size. Most lesions were covered with a mucus cap. Macroscopically, (semi) pedunculated morphology, double elevation, central depression, and reddishness were found more frequently in SSA/P with cytologic dysplasia and invasive carcinoma ([semi] pedunculated morphology, 17.1%/28.6%; double elevation, 63.4%/57.1%; central depression, 9.8%/28.6%; reddishness, 39.0%/85.7%) than in those without dysplasia (4.6%, 4.6%, 3.9%, and 3.4%, respectively). Furthermore, the presence of at least 1 of these 4 markers had high sensitivity (91.7%) for identifying the dysplasia/carcinoma within a SSA/P, with a specificity of 85.3%. In the pit pattern analysis, all SSA/Ps without dysplasia exhibited type II pit pattern only, whereas 94.4% of SSA/Ps with dysplasia/carcinoma showed type II in addition to type IIIL, IV, VI, or VN pit patterns. Conclusions: In an SSA/P series, endoscopic characteristics, including (semi) pedunculated morphology, double elevation, central depression, and reddishness, in addition to the use of magnifying endoscopy, may be useful to accurately diagnose advanced histology within an SSA/P.