0I型を呈したEpstein-Barr virus関連早期胃癌の1例

Epstein-Barr Virus-Associated Early Gastric Carcinoma Presenting as Protruded Type, Report of a Case

　症例は68歳，男性．検診にて胃に異常を指摘され当科を受診した．胃X線および内視鏡所見では胃体下部後壁に約30mm大の0I型隆起性病変を認め，生検にて印環細胞癌と診断された．遡及的に1年9か月前の内視鏡所見を確認したところ，同部位には0IIc様病変が認められ，0IIc型から0I型へ形態変化を来したと推察された．幽門側胃切除術を施行した結果，病理組織学的に深達度SMの低分化型腺癌が主体であるリンパ球浸潤性髄様癌であった．また病変の表層は高分化型腺癌にて覆われていた．in situ hybridization法にてEpstein-Barr virus（EBV）陽性であり，EBV関連胃癌であった．

　A 68-year-old man visited our hospital for further examination for a gastric lesion. Barium meal and endoscopic examinations revealed a protruded gastric tumor on the posterior wall of the gastric body, measuring approximately 3 cm in size. The tumor was diagnosed by biopsy as signet ring cell carcinoma. Endoscopic findings one year and nine month before showed a depressed lesion in the same area of the stomach. Distal gastrectomy was performed. Histologically, poorly differentiated adenocarcinoma with lymphoid stroma was found in the submucosal invasive area and well differentiated adenocarcinoma component coexisted in the mucosa. Epstein-Barr virus (EBV) encoded RNA-1 was positive in the nuclei of the carcinoma cells, proving this case was an EBV-associated gastric cancer.