Helicobacter pylori陰性患者に認めた胃底腺型胃癌の1例

Gastric Adenocarcinoma of the Fundic Gland Type in a Patient without Helicobacter pylori Infection, Report of a Case

要旨●患者は65歳，男性．少量の血便を契機に当院を受診した．上部消化管内視鏡にて胃体中部大彎に辺縁がなだらかに隆起する褪色調の陥凹性病変を認め，近接観察にて拡張・蛇行した血管網が観察された．NBI拡大観察では陥凹部の表面微細構造は軽度不整であったが，癌の診断は困難であった．なお，背景粘膜に萎縮はなく，H. pylori陰性であった．生検にて異型上皮が検出され，診断確定および治療目的にESDを施行した．病理組織学的には粘膜深層を中心に軽度の構造異型を有する胃底腺類似の腫瘍細胞が発育しており，わずかに粘膜下層へ浸潤していた．免疫染色ではMUC6およびpepsinogen-Iが陽性であり，胃底腺型胃癌（主細胞優位型）と診断した．

　A 65-year-old man with a history of hematochezia underwent esophagogastroduodenoscopy. A small whitish depressed lesion was observed at the greater curvature of the gastric body. Tortuous and dilated vessels were also observed in the depression. Magnifying endoscopy with narrow-band imaging revealed insignificant irregularity of the microsurface structure in the depressed area. Mucosal atrophy was not observed in the surrounding mucosa, and there was no evidence of Helicobacter pylori infection. Atypical epithelium was found in the biopsy specimen; therefore the lesion was resected using endoscopic submucosal dissection. Histologically, the resected tumor was diagnosed as gastric adenocarcinoma of the fundic gland type（chief cell predominant type）. This type of gastric adenocarcinoma should be considered in differential diagnosis, even if no obvious tumor is observed under magnifying endoscopy.