Tu1471 Pathological Characteristics of "Skirt" Spreading on the Margin of Rectal Laterally Spreading Tumors

Abstract

of SMI are absent, the finding of SMF or IPB in a lesion O30mm should prompt re-evaluation. Tu1470 Clinicopathological Features of Laterally Spreading Tumor of the Colorectum : References Among Subtypes and Submucosal Invasion Tomoyuki Ishigaki*, Shin-Ei Kudo, Takemasa Hayashi, Yusuke Yagawa, Katsuro Ichimasa, Naoya Toyoshima, Hiromasa Oikawa, Yuichi Mori, Masashi Misawa, Toyoki Kudo, Tomokazu Hisayuki, Kunihiko Wakamura, Hideyuki Miyachi, Eiji Hidaka, Fumio Ishida Digestive Disease Center, Showa University Northern Yokohama Hospital, Yokohama-SHI, Japan Background / aims: Laterally spreading tumors (LSTs) are usually good indication for endoscopic treatment because they are rather benign in spite of their large diameter. There are four subtypes in LSTs; granular type (homogeneous type (H) / nodular mixed type (M)), and non-granular type (flat-elevated type (F) / pseudodepressed type (PD)). Their pathological features are different among subtypes. The aim of this study is to evaluate the clinicopathologial features of LSTs focusing on their subtypes and submucosal(SM) invasion. Methods: In a retrospective review of the colonoscopy database (Apr 2001 to Mar 2013) at our institution, we selected cases of colorectal neoplasms based on the following criteria; endoscopically diagnosed cases of LSTs that underwent subsequent endoscopic or surgical resection. We evaluated clinicopathological features (gender, age, size, rate of SM invasion) according to LSTs subtypes. Furthermore, we examined the LSTs with SM invasion which treated from Apr 2010 to Mar 2013 focusing on their locus of SM invasion. For analysis, we used chi-square test and one way ANOVA post hoc test for statistical analysis. Results: A total of 2035 LSTs were eligible for inclusion. The main results are shown in the table.0As the three types of LST(G(M)/NG(F)/NG(PD)) became larger, the ratio of submucosal invasion became higher. But LST-G(H) showed low rate of that even when they were large in diameter. 0LST-NG(PD) had higher ratio of submucosal invasion (44.8%; 90/201) than the other types (P!0.01).BLSTs with SM invasion which treated from Apr 2010 to Mar 2013 were 85 lesions.0The locus of SM invasion at LST-G(M) was almost(77.8%; 21/27) under nodule.0In LST-NG(PD), SM invasion was tend to occur multifocally(41.7%; 10/24) compared with the other type(11.5%; 7/61) (P! 0.01). Conclusions: Clinicopathological features of LSTs are different among subtypes, therefore we have to select the treatment method carefully according to LST subtypes.