粘膜下腫瘍様の形態を呈した大腸癌の1例

Colon Cancer Mimicking Submucosal Tumor, Report of a Case

要旨　患者は57歳，男性．1996年9月，健診で便潜血反応陽性を指摘された。注腸X線検査でS状結腸に中心陥凹を伴う粘膜下腫瘍様の隆起性病変を認めた．大腸内視鏡検査で中心陥凹を伴う正常上皮に覆われた粘膜下腫瘍様隆起性病変を認め，拡大内視鏡観察ではほとんどの部分で正常の1型，中心陥凹部ではV型，周辺隆起部に散在性に小類円形のV型pit patternを認めたことから粘膜下層以深に進展した大腸癌と判断し，S状結腸切除術を施行した．病理組織学的には固有筋層に進展した大腸進行癌と判明した．また拡大内視鏡でV型pit patternの部分は，病理組織では癌の粘膜面露出部に一致していた．粘膜下腫瘍様の形態を呈した大腸癌は比較的まれであり，大腸癌の発育進展を考えるうえで貴重な症例と思われ報告した．

　A 57-year-old man was admitted to our hospital because of positive fecal occult blood.

　Barium enema examination revealed a polypoid lesion with a central depression in the sigmoid colon.

　Colonoscopy visualized the same findings. Magnifying endoscopic examination disclosed the surface of the lesion was the same as that of the surrounding mucosa.

　The resected specimen showed the lesion was dis-coid-shaped with a central depression on the top, measuring 28 × 22 mm in size. Most of the surface was covered with normal epithelium that was seen in the surrounding mucosa. Histological examination of the resected specimen showed well-differentiated adenocarcinoma which was located in the ulcerated area of the mucosal layer and invaded the submucosal layer with tumor mass formation.