ひだ集中を伴った側方進展型大腸sm癌の1例

Lateral Spreading Type Cancer of the Colon with Submucosal Invasion and Converging Folds, Report of a Case

要旨　患者は44歳，女性．1990年6月，大腸内視鏡検査で直腸ポリープを指摘され内視鏡的摘除を受けた．病理診断は腺腫であった．その後，毎年全大腸内視鏡検査を受けていたが，1994年4月，下行結腸にひだ集中を伴う平坦な病変を認め，生検でGroup5と診断されたため精査加療目的で当科入院となった．注腸検査では周囲から数本のひだ集中を伴う平坦な隆起性病変を認め，側面像で腫瘍の中心部にひきつれがみられた．内視鏡検査では，軽度発赤調で，血管透視像の消失を示す境界不明瞭な病変として認められたが，色素撒布後には境界明瞭となった．空気量の増減で周囲からのひだが集中する部位に軽度の伸展不良が認められた．以上の所見からsmへの癌浸潤を疑い外科的切除を行った．病理学的検索では，大きさ27×25mmの扁平病変で，組織学的には高分化型腺癌であった．腫瘍の大部分は粘膜内癌であったが，一部sm₂への浸潤を認め，粘膜下層に比較的広い範囲にわたって線維化がみられた．本例は腫瘍の丈が低く，腸管壁に沿って水平方向を主体に腫瘍が発育しており，いわゆる結節集簇様形態をとらない非結節型の側方進展型腫瘍と考えられた．

　A 44-year-old woman visited our hospital because of follow-up colonoscopic examination for a rectal adenomatous polyp endoscopically resected four years before. Total colonoscopic examination revealed a flat-topped elevation in the descending colon, and the biopsy specimens disclosed well differentiated adenocarcinoma. Double-contrast barium study revealed a slightly elevated lesion with converging folds in the proximal descending colon. Lateral view of the lesion on radiographic examination showed stiffness of the colonic contour. Endoscopically, the flat-topped elevation was slightly red, and dye spraying technique clarified the margin of the lesion. Endoscopic examination with small amount of pneumatic expansion revealed luminal stiffness in the center of the lesion and converging folds. The tumor was diagnosed to be associated with submucosal invasion and was resected surgically. The resected specimen showed a slightly elevated lesion measuring 27×25 mm in diameter with converging folds. Histologic examination revealed well differentiated adenocarcinoma whose main part was located in the mucosal layer and partly invading the submucosal layer. Extensive fibrosis was also seen in the submucosal layer. We diagnosed this case as a lateral spreading type tumor which was distinct from nodule aggregating lesions.