拡大内視鏡にてVN型pit patternを呈したIIc＋IIa型直腸粘膜内癌の1例

Type 0-IIc＋IIa Rectal Intramucosal Carcinoma which was Diagnosed as Type VN Pit Pattern by Magnifying Colonoscopy, Report of a Case

要旨　患者は59歳，男性．大腸ポリペクトミー後の経過観察にて直腸病変を指摘された．大腸内視鏡にて直腸S状部に10mm大の境界明瞭な陥凹性病変を認めた．肛門側には辺縁隆起を伴い，陥凹内部にさらに一段深い陥凹を認めた．拡大内視鏡では陥凹内部はV_I型，一段深い陥凹部はV_N型を呈し，藤井らのInvasive patternと診断した．術前深達度SM₂と診断の上，腹腔鏡補助下高位前方切除術を施行した．病理診断は高異型度高分化～中分化腺癌，深達度m，ly₀，v₀，n(－)であった．V_N型を呈した理由として同部は中分化腺癌から構成され，表層は被覆上皮が脱落し，びらんを形成していたためと考えられた．

　A 59-year old man underwent colonoscopy for surveillance after polypectomy. Conventional colonoscopy revealed a reddish depressed lesion, 10mmin diameter, with flat elevation in an anal part of the upper rectum. There was a deeper depressed area in the lesion. Magnifying colonoscopy showed type VI pit pattern in the depression, and type VN pit pattern in the deeper depressed area. This pit pattern was diagnosed as “Invasive pattern” as proposed by Dr. Fujii. The lesion was diagnosed as a rectal cancer with deep submucosal invasion, and the patient underwent laparoscopic assisted high anterior resection. However, pathological diagnosis was well to moderately differentiated adenocarcinoma limited in the mucosal layer. There was neither vessel permeation nor lymph node metastasis. The VN pit pattern was due to the erosive surface of the lesion that consisted of moderately differentiated adenocarcinoma. We should recognize that a high grade cancer appears to have type VN pit pattern even if it is an intramucosal cancer.

　1) Department of Gastroenterology, Saku Central Hospital, Nagano, Japan