胃癌と合併した粘膜下腫瘍様の胃型十二指腸腺腫の1例

Gastric-Type Duodenal Adenoma in the Shape of Submucosal Tumor (SMT) Accompanied by a Gastric Cancer, Report of a Case

要旨　患者は64歳，男性．近医の上部消化管内視鏡検査にて，胃癌とともに十二指腸主乳頭のやや肛門側に，径約2cmの粘膜下腫瘍(SMT)様病変が発見された．表面陥凹部には腫瘍が露出し，同部からの生検は管状腺腫であった．手術は胃切除術に加えて，十二指腸切開下に粘膜部分切除術を施行した．十二指腸腫瘍の組織診断は，一部に高度の異型を示す管状腺腫で，腫瘍深部に胃上皮様部分がみられた．また，粘液染色にて胃型粘液の45M1・MUC-1が陽性であった．胃型上皮由来の腺腫/癌の報告は，過去に7例あり，本例を含めて8例中5例が山田III型(うち2例がSMT様)で，3例に中心陥凹がみられた．中心陥凹を有し，同部に腫瘍が露出するSMT様の形態は，十二指腸の胃型腫瘍に特徴的である可能性がある．

　A 64-year-old man was diagnosed by a physician of a neighboring hospital endoscopically, as having both a gastric cancer and a duodenal SMT-like tumor simultaneously. He was admitted to our hospital for more precise examination. The duodenal tumor, existing close to the papilla of Vater, had a central depression on its surface. Some biopsy specimens taken from the depression were diagnosed histologically as tubular adenoma with moderate atypia. We carried out partial resection of the duodenal mucosa, including the tumor, immediately after partial distal gastrectomy. Histological diagnosis of the resected specimen was tubular adenoma with severe atypia accompanied by gastric-type epithelium within the tumor. Immunohistochemical staining indicated that gastric mucin, 45M1 and MUC-1 were both positive, so this duodenal tumor seems likely to have arisen from gastric-type epithelium. Our case was the eighth case of gastric-type duodenal tumors already reported in the world. Five of the eight cases had the shape of type III of Yamada's classification, in which three had a central depression on the surface and two looked like SMT. We think that SMT-like tumor with central depression in the duodenum is probably derived from gastric-type epithelium, because this shape is quite uncommon among epithelial duodenal tumors.