漿膜下層に脈管侵襲を認めた進行胃底腺型胃癌の1例

Advanced Stage of Gastric Adenocarcinoma of Fundic Gland Type with Venous Invasion in the Subserosa, Repot of a Case

要旨●患者は62歳，男性．検診目的に施行した上部消化管内視鏡検査で胃癌の診断を受け，精査加療目的に入院となった．通常光観察で胃体下部小彎後壁寄りに20mm大の陥凹型病変を認めた．H. pyloriは陰性であったが，背景粘膜は萎縮化生性変化を認め，H. pylori自然消退例の可能性が示唆された．NBI拡大観察を用いたVS classification systemでirregular microvascular pattern plus relatively regular microsurface pattern with a demarcation lineと診断し，粘膜下層浅層までの浸潤にとどまった分化型早期胃癌0-IIc型と判断した．ESDによる一括切除を施行し，胃底腺に類似した腫瘍腺管から成る高分化型腺癌の所見を認めた．免疫染色にてpepsinogen Iが陽性かつ胃型の粘液形質発現を認め，胃底腺型胃癌と診断した．腫瘍細胞は予想外に陥凹局面の外側にまで進展を認めた．また，脈管侵襲が目立ってみられたため，腹腔鏡下胃全摘術およびD2郭清を追加施行した．その結果，漿膜下組織への脈管侵襲が確認された．最終的にT3N0M0，Stage IIAの進行胃癌であった．

　A 62-year-old Japanese man was referred to our institution for gastric cancer treatment. Endoscopic examination revealed a depressed lesion approximately 20mm in size at the lesser curvature of the lower gastric body. All Helicobacter pylori（H. pylori）tests were negative ; however, atrophic mucosa with intestinal metaplasia suggested spontaneous eradication of H. pylori. According to the VS（vessel plus surface）classification, magnifying endoscopy with narrow-band imaging showed an irregular microvascular pattern in addtion to a relatively regular microsurface pattern with a demarcation line. We suspected this lesion to be an early stage type 0-IIc differentiated adenocarcinoma that was either limited to the mucosa or had minimal invasion into the submucosa. En bloc endoscopic submucosal dissection revealed a well-differentiated adenocarcinoma mimicking fundic gland cells, which were positive for pepsinogen-1 and, hence, classified as a gastric mucin phenotype. These findings were consistent with a GA-FG（gastric adenocarcinoma of fundic gland type）. Unexpectedly, cancer cells were extensively spread beyond the area of depression. Because massive lymphovenous invasions were observed, a total gastrectomy with lymph node dissection was performed. Consequently, subserosal venous invasion has occurred with cancer cells. The final pathological stage was noted as IIA（T3N0M0）.