These tumor vessels were equivalent to B type vessel of the Japan Esophageal Society ME Classification in most part. Anal border, which was close to dentate line, was well demarcated with NBI. The lesion did not look rigid endoscopically, which changed the shape smoothly by air inflation. These observations indicated that the lesion was a mucosal carcinoma. We performed en bloc resection of the tumor by endoscopic submucosal dissection

(ESD). Results: The tumor was 0-IIc type and 24 mm in diameter. A pathological diagnosis of Squamous cell carcinoma, pTis, ly0, v0, VM (−), HM (−) was made. Conclusion: As for anal canal cancer, the frequency in all colon cancer was 0.7–1.8% in literatures. Most of them are adenocarcinoma; squamous Ruxolitinib datasheet cell carcinoma is relatively rare. This is the first report of depressed-type squamous cell carcinoma at anal canal, which was treated by ESD. Key Word(s): 1. Anal canal cancer. scc. ESD Presenting Author: SOO Sorafenib mw KYUNG PARK Additional Authors: BONG MIN KO, JAE

PIL HAN, SU JIN HONG, SEONG RAN JEON, JIN OH KIM, JOO YONG CHO, MOON SUNG LEE Corresponding Author: SOO-KYUNG PARK Affiliations: Soonchunhyang University School of Medicine, Soonchunhyang University School of Medicine, Soonchunhyang University School of Medicine, Soonchunhyang University School of Medicine, Soonchunhyang University School

of Medicine, Soonchunhyang University School of Medicine, Soonchunhyang University School of Medicine Objective: Endoscopic submucosal dissection (ESD) is one of the curative endoluminal surgical procedures for colorectal Methane monooxygenase epithelial neoplasms. Although second-look endoscopy (SLE) is frequently performed after gastric ESD, no reports have assessed the role of SLE in colorectal ESD. We investigated whether a SLE after ESD is effective in the prevention of delayed bleeding. Methods: This study included 173 consecutive patients in whom 174 left-sided colorectal epithelial neoplasms were resected using ESD between March 2005 and December 2013. After removal of the lesion, preventive post-ESD-coagulation for all visible exposed vessels or prophylactic clip closure for ulcer was performed. In the patients who performed SLE, the post-ESD ulcers were categorized according to the Forrest classification: high-risk ulcer stigma (type I and IIa) and low-risk ulcer stigma. We classified patients into two groups on the basis of performing SLE and retrospectively compared delayed bleeding. Results: SLE was performed in 97 (55.7%) lesions on the day following ESD. SLE revealed that the incidence of type IIb and III ulcer stigma was 38 (39.2%) and 59 (60.8%) respectively and there was no high risk ulcer stigma.