深達度診断に苦慮した0-IIc型大腸SM癌の1例─マイスナー神経叢同定の試み

Type 0-IIc Colon Cancer with Submucosal Invasion That was Difficult to Diagnose Histopathologically: Identification Through the Meissner's Plexus, Report of a Case

要旨●患者は70歳代，男性．大腸内視鏡検査にて横行結腸に病変を指摘され，当科へ紹介となった．注腸X線造影検査にて横行結腸肝彎曲近傍に陥凹性病変を認めたが，SM深部浸潤を示唆する所見に乏しかった．大腸内視鏡検査では病変の陥凹内にわずかな隆起と緊満感を認め，クリスタルバイオレット染色拡大観察ではV_I型高度不整のpit patternを示し，SM深部浸潤が疑われた．EUSでも第3層の菲薄化が疑われ，SM深部浸潤を疑う所見であった．完全摘除生検目的としてESDを施行した．術後標本でも深達度診断に苦慮する症例であったが，マイスナー神経叢を同定し，SM浸潤距離を推定する方法を施行した．

　A 70-year-old man was referred to our department for further investigations because a previous colonoscopy revealed a lesion in the transverse colon. A barium contrast study of the colon revealed a depressed lesion in the hepatic flexure. Conventional colonoscopy revealed a depressed lesion with localized slightly protruded area suggests cancer invasion reaching the submucosa. Magnification colonoscopy with crystal violet staining demonstrated type V_I high-grade pit pattern at the localized lesion. Furthermore, endoscopic ultrasound revealed thinning of the third layer. Therefore, we assumed massive submucosal invasion of the cancer and performed an endoscopic submucosal dissection to achieve en bloc resection. It was difficult to clearly determine the level of invasion ; however, we identified the Meissner's plexus and estimated the depth of submucosal invasion.