十二指腸非乳頭部に発生した胃型粘膜下層浸潤癌の1例

Submucosally Invasive Adenocarcinoma of Gastric-type Occurring in Non-ampullary Duodenum, Report of a Case

要旨●患者は80歳代，男性．EGDで十二指腸球部に周囲粘膜と同色調ないし発赤調の亜有茎性隆起性病変を認めた．腫瘍頂部には乳頭状の表面構造を認め，病変基部に不整な小型顆粒状構造を認めた．NBI併用拡大観察では胃腺窩上皮様の形状不均一な表面構造と密な腺管構造がみられ，クリスタルバイオレット染色像では不均一な松毬様所見が観察された．以上より，胃型十二指腸癌と診断し，ESDを施行した．病理組織学的所見では腺窩上皮に類似した高円柱状上皮と深部の不規則な管状腺管がみられ，頂部からの浸潤距離は10,000μmを超えていた．腫瘍細胞はMUC2陰性，MUC5AC陽性，MUC6一部陽性，CD10陰性であり，腺窩上皮型優位の胃型腺癌と診断した．追加外科手術を行い，リンパ節転移は認めなかった．治療後5年間無再発で経過している．

　A man in his 80s underwent esophagogastroduodenoscopy that revealed an enlarged lesion with a diameter of 15mm in the duodenal bulb. The top of the tumor had a papillary surface pattern as in gastric foveolar. The base of the tumor was reddish and had an irregular small granulated pattern. Magnifying endoscopy with crystal violet staining revealed an irregular pine-cone pattern. The lesion was finally diagnosed as gastric-type adenocarcinoma and was treated by endoscopic submucosal dissection. Histopathological examination revealed a well-differentiated adenocarcinoma that had invaded the duodenal submucosa. On immunohistochemical examination, the lesion was positive for MUC5AC and MUC6 ; therefore, we confirmed the diagnosis as gastric-type adenocarcinoma. Additional surgery was performed, and no metastases were found in lymph nodes. Genetic analyses identified KRAS and GNAS mutation. There has been no evidence of recurrence for 5 years after surgery.