印環細胞癌を主体とし多彩な組織像を呈した小さな大腸癌の1例

A Small Colonic Adenocarcinoma with Various Histologies, Accompanied by Mucinous Adenocarcinoma, Report of a Case

要旨　56歳，女性．スクリーニングを目的とした大腸内視鏡検査にて横行結腸に粘膜下腫瘍様の小隆起性病変を指摘された．生検組織の病理診断では印環細胞癌であった．外科的摘出標本の病理組織学的検討においては多彩な組織像を認めた．長径が1.5cmの小病変であったが印環細胞癌，粘液癌，低分化から高分化の腺癌および内分泌細胞癌類似の組織所見を混在する病変であった．組織の移行像ならびに同じ粘液形質を有することから粘膜内の低異型度分化型腺癌から種々の形態変化を来した症例と考えられた．

　An operation for hemorrhoids was carried out on a 56-year-old female, and then further examinations were performed for the whole colon. Colonoscopy revealed the existence of a polypoid lesion with mucus on the surface in the transverse colon. Barium enema examination showed the lesion was like a submucosal tumor, measuring 15 mm in size. Endoscopic ultrasonography revealed that the 3rd layer was thickened and the 4th layer was clear, so we diagnosed that the lesion was early cancer with submucosal invasion. A partial colectomy of the transverse colon was performed. Histological examination revealed that the tumor consisted of a signet-ring cell carcinoma, a well to moderately differentiated adenocarcinoma, and a mucinous adenocarcinoma.