粘膜下腫瘍様の形態を呈した胃リンパ球浸潤癌（GCLS）の1例

A Gastric Carcinoma with Lymphoid Stroma Exhibiting Features of a Submucosal Tumor, Report of a Case

要旨　患者は52歳，男性．検診にて異常を指摘され当院を受診した．X線検査では，大きさ20mm大で中心にニッシェを伴った類円形の粘膜下腫瘍様隆起として描出された．深いニッシェ周囲には浅い不整形の陰影斑を伴っており，粘膜下腫瘍様の形態を呈した癌を疑った．肉眼形態よりSM2に浸潤した癌と診断したが，側面像では壁硬化，変形に乏しかった．内視鏡検査でも，壁強伸展で伸展不良所見を認めず，壁伸展の程度で隆起の丈が変化し，通常のSM癌より軟らかい印象であった．超音波内視鏡検査では第3層を主座とする内部エコー均一な低エコー腫瘤として描出され，SM癌が疑われた．中心陥凹部辺縁より採取した生検で低分化腺癌と診断され，幽門側胃切除術を施行した．病理組織学的所見では0-I＋IIc型，poorly differentiated adenocarcinoma with lymphoid stromaと診断され，pT1b2（SM2），ly0，v0で,リンパ節転移は認めなかった．なお，EBV（Epstein-Barr virus）陽性であり，EBV関連胃癌と考えられた．

　A 52-year-old male visited our hospital because of an abnormality found during a medical examination. X-ray images showed a 20mm roundish submucosal tumor-like protrusion at the greater curvature of the lower corpus with a deep depression in the center. A shallow irregularly shaped shadow was in the margin of the deep depression, and a SM（submucosal）cancer exhibiting submucosal tumor-like morphology was suspected. However, lateral images showed a slight wall deformation. In addition, on endoscopy, no bad extension was found in the strong wall extension, but the height of the protrusion changed according to the degree of the wall extension and it seemed softer than the normal SM invasive cancer. Endoscopic ultrasonography showed a hypoechoic mass mainly located in the second and third layers. From a biopsy of the margin of the central depression, the patient was diagnosed as having poorly differentiated adenocarcinoma and underwent a distal gastrectomy. The histopathological findings revealed 0-I＋IIc type poorly differentiated adenocarcinoma with lymphoid stroma, pT1b2(SM2）, ly0, v0, and no lymph node metastasis. EBV（Epstein-Barr virus）was positive, suggesting EBV-related gastric cancer.