低分化腺癌を主体にして亜有茎性隆起を形成した1型進行胃癌の1例

Advanced Gastric Carcinoma Predominantly Composed of Poorly Differentiated Adenocarcinoma Presenting as a Subpedunculated Protrusion, Report of a Case

要旨　症例は53歳，男性．検診目的の上部消化管内視鏡検査で，胃体上部前壁に大きさ2cmの隆起性病変を指摘された．病変は亜有茎性で多結節状隆起を呈し，基部辺縁に発赤した平坦領域と浅い陥凹を伴っていた．隆起部の生検診断は低分化腺癌であった．胃X線検査では，病変は2個の粗大結節から構成され，側面変形が認められた．超音波内視鏡検査では，腫瘍の中央で第3層が断裂していたことから，深達度を粘膜下層の深層（sm3）と推測したが，固有筋層（mp）への浸潤も疑われた．以上の所見から進行胃癌の可能性を考慮し，胃全摘術を行った．病理組織学的には，低分化腺癌を主体とし，印環細胞癌を混在する深達度mpの1型胃癌であった．自験例が示すように，隆起型胃癌の内視鏡診断では，隆起形態とともに基部辺縁の陥凹や平坦病変に着目し，未分化型癌の可能性を考慮する必要があると思われた．

　A 53-year-old Japanese man was admitted to our hospital for the purpose of treatment of a polypoid tumor of the stomach, found incidentally by gastroscopy. The endoscopic examination revealed a subpedunculated nodular tumor accompanied by a flat area and a shallow depression at the margin of the protrusion, on the anterior wall of the upper body. Biopsy specimens taken from the tumor disclosed poorly differentiated adenocarcinoma. A double contrast x-ray study showed a protruding tumor composed of two nodular components, with a deformity seen on the lateral view. Endoscopic ultrasonography demonstrated the tumor to be a hypoechoic mass with massive invasion of the submucosa and possibly of the muscularis propria. The protruding lesion, after total gastrectomy, revealed a polypoid tumor measuring 2.0×1.5cm in size with a slightly depressed area. Histopathology showed a poorly differentiated adenocarcinoma coexistent with signet-ring cell carcinoma with invasion of the muscularis propria. When making an endoscopic diagnosis of the protruding-type gastric carcinoma, it is important to observe not only the the protrusion but also the margin of the tumor.

　1) Department of Internal Medicine, Okayama Kyoritsu Hospital, Okayama, Japan