鋸歯状腺腫とSSA/Pを併存した粘膜内癌の1例

Focal Adenocarcinoma Arising from Traditional Serrated Adenoma Concomitant with Sessile Serrated Adenoma/Polyp, Report of a Case

要旨　患者は50歳代，女性．主訴は下血．大腸内視鏡検査にて上行結腸に35mm大の褪色調を呈する扁平隆起性病変を認めた．中心部には10mm大の結節性隆起を伴っていた．拡大内視鏡観察では肛門側扁平隆起部にII型pit，口側扁平隆起部にIV_H型pit，結節性隆起部にはV_I軽度不整を認め，SA（serrated adenoma）in HP（hyperplastic polyp）と診断した．結節性隆起部に粘膜内癌の存在を疑い，内視鏡的粘膜下層剝離術にて一括切除した．病理組織学的所見では肛門側扁平隆起部にSSA/P（sessile serrated adenoma/polyp），口側扁平隆起部にTSA（traditional SA），結節性隆起部にSCa（serrated carcinoma）を認めた．本例はSSA/PとTSAを併存し，TSAからserrated pathwayを経て発生した腺癌と考えられた．

　We present a fifty year-old female with a pale, flat, 35mm in diameter lesion concomitant with a protruded nodule in the ascending colon. Magnifying endoscopy with crystal violet staining demonstrated type II pit pattern within the oral flat area, type IV_H pit pattern within the anal flat area, irregular V_I pit pattern within the protruded nodule. We diagnosed it as a serrated adenoma in a hyperplastic polyp, and achieved en bloc resection using endoscopic submucosal dissection. Histological evaluation revealed a serrated carcinoma within a sessile serrated adenoma/polyp and traditional serrated adenoma. We considered it as a focal adenocarcinoma arising from traditional serrated adenoma concomitant with sessile serrated adenoma/polyp via the serrated pathway.