X線的に遡及的検討が可能であったⅡa＋Ⅱc型大腸sm癌の1例

Type Ⅱa ＋ Ⅱc Submucosal Cancer of the Colon Retrospectively Evaluated, Report of a Case

要旨　患者は64歳，男性．12年前にS状結腸のIp型早期癌を内視鏡的に切除され，経過観察目的の大腸内視鏡検査で，上行結腸に中央に不整形陥凹を伴う発赤調扁平隆起が発見された．精密X線検査では，18×11mmの丈の低い結節状周辺隆起を伴う不整形陥凹として描出され，Ⅱa＋Ⅱc型早期大腸癌と診断し，上行結腸切除術を施行した．病理組織学的には12×10mmのⅡa＋Ⅱc型の分化型腺癌で大部分はm内にとどまり，sm浸潤はごくわずかであった（sm₁）．この病変は2年4か月前の注腸X線写真を見直すと，ほぼ同じ大きさ，形態で描出されていた．陥凹を伴う表面型大腸癌は深部浸潤速度が速いと言われているが，本例のように緩徐な発育進展を呈するものも存在すると考えられた．

　A 64-year-old man had undergone polypectomy for a type Ip early cancer in the sigmoid colon 12 years before. Colonoscopic examination for surveillance revealed a reddish flat elevation with an irregular depression in the ascending colon. Barium enema showed a flat elevation with an irregular depression, 18 × 11 mm in size. The lesion was diagnosed as type Ⅱa ＋ Ⅱc early cancer, and surgical resection of the ascending colon was performed. Histologically, the lesion proved to be a well differentiated adenocarcinoma, type Ⅱa ＋ Ⅱc in shape, 12 × 10 mm in size, mainly restricted to the mucosa and partially invading the submucosa (sm₁). We reviewed the x-ray photograph taken two years and four months before, and found the lesion detected them to be almost the same size and shape as the one resected. Superficial type colonic cancer with a depression is said to have a rapid invasion rate. However, it was suggested that some of such cancers, examplified by our case, have a slow growth rate.