胃粘膜下腫瘍様の形態を呈した胃癌の1例

Gastric Cancer Resembling Submucosal Tumor, Report of a Case

要旨　患者は64歳の男性で，黒色便を主訴に当科に来院した．胃X線検査および胃内視鏡検査で胃体中部小彎にbridging foldを有する正常粘膜で被覆された母指頭大の粘膜下腫瘍様隆起を認めた．頂部には不整形の浅い陥凹がみられ，この辺縁にⅡC様の蚕食像が認められた．陥凹からの生検で低分化腺癌の組織が得られ，EUSでは隆起部に一致して第4層まで達する腫瘤がみられたことから進行胃癌と術前診断した．切除標本の病理学的検索では隆起を形成していたのは粘膜下層を主体に発育し漿膜下層に及ぶ低分化腺癌であった．粘膜下腫瘍様形態を呈する胃癌の診断には胃X線検査および内視鏡検査による詳細な観察が重要であると考えられた．

　The patient was a 64-year-old male who was admitted to our department with tarry stool as his chief complaint. X-ray and endoscopical examination revealed a protruded lesion similar to a submucosal tumor accompanied with irregular depression on its surface in the lesser curvature of the middle body. Slight Ⅱc-like encroachment was seen in the margins of the depression in the close-up view of the endoscopic examination. Gastric cancer was histologically diagnosed by biopsy from the depression. EUS showed a solid tumor invading from the submucosa to the subserosa. Therefore, we diagnosed advanced gastric cancer similar to submucosal tumor. Subtotal gastrectomy was performed. The resected specimen showed an elevated lesion, measuring 16 × 12 mm, accompanied with irregular depression on its surface in the lesser curvature of the middle body. Histologically, the protruded lesion consisted of a proliferation of poorly differentiated adenocarcinoma with partial mucinous degeneration deeper than the submucosal layer.

　It is rare that gastric cancer develops in a manner similar to submucosal tumor such as in this case. Detection of Ⅱc-like encroachment using close radiological and endoscopical examination might make it possible to diagnose gastric cancer similar to a submucosal tumor.