粘膜下腫瘍様の形態を示したEpstein-Barr virus（EBV）関連早期胃癌の1例

Epstein-Barr Virus-associated Early Gastric Cancer Mimicking Submucosal Tumor, Report of a Case

要旨　症例は73歳の女性．体重減少を主訴に当院受診，上部消化管内視鏡検査にて異常を指摘された．胃X線では体上部前壁にbridging foldを伴う粘膜下腫瘍様の隆起性病変を認め，隆起の頂部には星芒状の陥凹を有していた．胃内視鏡検査では陥凹辺縁に蚕食像を認めた．胃亜全摘術が施行され，病理診断はpor2，pT1（sm），infα，ly0，v0，n0であった．腫瘍細胞は著明なリンパ球浸潤を伴って粘膜下層に浸潤しており，いわゆるリンパ球浸潤性髄様癌であった．免疫組織学的検索にてEBV-encoded small RNA (EBER)-1 in situ hybridization陽性であり，Epstein-Barr virus関連胃癌と考えられた．

　A 73-year-old female visited our hospital for examination of body weight loss. X-ray and endoscopic examination of the stomach showed a protruded lesion on the anterior wall of the upper gastric body. The lesion looked like a submucosal tumor, and it had an irregular small depression on the top of the protrusion. A biopsy of the lesion demonstrated poorly differentiated adenocarcinoma. Endoscopic ultrasonography revealed a hypoechoic tumor in the second to third layer. Distal gastrectomy was performed. Histological investigation showed a poorly differentiated adenocarcinoma extending to the submucosa with marked infiltration of lymphocytes. This was thought to be a gastric cancer with lymphoid stroma (GCLS). Immunohistological investigation showed that Epstein-Barr virus encoded RNA (EBER)-1 in situ hybridization was positive in the nuclei of the cancer cell, so it was considered to be an Epstein-Barr virus-associated gastric cancer.

　1) Department of Therapeutic Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan

　2) Department of Gastroenterology, Ogaki Municipal Hospital, Ogaki, Japan

　3) Department of Pathology, Ogaki Municipal Hospital, Ogaki, Japan