Efficiency of endocytoscopy in differentiating types of serrated polyps

Background: Accurate endoscopic criteria are needed to differentiate serrated polyps, including hyperplastic polyp (HP), sessile serrated adenoma/polyp (SSA/P), and traditional serrated adenoma (TSA), because some are precursors of colorectal cancers. Objective: To determine the endocytoscopic features of each type of serrated polyp, especially the shapes of lumens and nuclei. Design: Retrospective study. Setting: Single, tertiary-care referral center. Patients: Patients who underwent removal of serrated polyps from May 2005 to December 2012. Intervention: Endocytoscopy was performed. Endocytoscopic images were evaluated by assessing the shapes of the lumens and nuclei of the target lesions. Main Outcome Measurements: The significant endocytoscopic features in differentiating among types of serrated polyps. Results: Of the 58 eligible lesions, 27 were classified as HP, 12 as SSA/P, and 19 as TSA. Most HPs (77.8%) had star-like lumens, and most SSA/Ps (83.3%) had oval lumens. The lumens of TSAs were serrated (31.6%) or villous (68.4%), with both shapes seen only in TSAs. Most HPs (92.6%) and SSA/Ps (75.0%) had small, round nuclei, and all TSAs had fusiform nuclei. Features significantly differentiating TSAs from HPs and SSA/Ps were the presence of fusiform nuclei (P < .001) and villous (P < .001) and serrated (P = .002) lumens. The presence of oval lumens was significantly characteristic of SSA/Ps (P < .001), and the presence of star-like lumens was significantly characteristic of HPs (P < .001). Limitations: Retrospective design. Single-center study. Conclusion: The shape of lumens and nuclei on endocytoscopy can efficiently differentiate among the different types of serrated polyps. (Clinical trial registration number: UMIN Clinical Trials Registry UMIN000007850.)