経過を追えた表面型起源大腸癌の2例

Growth and Progression of Superficial Colorectal Neoplasms, Report of Two Cases

要旨　初回発見時の形態が平坦な隆起型であり，その後浸潤癌へと進展した大腸癌の2例を報告する。〔症例1〕は70歳，男性．初回の注腸X線検査で，S状結腸に浅い中心陥凹を伴う長径11mmの平坦な隆起性病変を認めた．内視鏡検査ではⅡa様の隆起がみられたが生検はGroup3であった．1年9か月後の注腸X線および内視鏡検査では，同部に中心陥凹を伴った長径21mmの結節状隆起を認めた．切術標本では，潰瘍限局型のpmまで浸潤した中分化腺癌であった．〔症例2〕は42歳，男性．内視鏡検査で下部直腸前壁に，長径約7mmの平坦な病変を認め，生検はGroup3であった．5年後，血便を主訴に再び来院し，内視鏡検査で前回と一致する部位に，浅い中心陥凹を伴う平盤状隆起を認め，生検でGroup5の診断が得られた．切除標本では，Ⅱa＋Ⅱc型のsmに浸潤した中分化腺癌であった．2例の発見時と切除時における，肉眼所見と組織所見の形態学的変化を考察した．

　We present two cases with superficial colorectal neoplasms which developed into invasive carcinomas. In one patient, initial barium enema and colonoscopic examinations revealed a flat elevated lesion with a central shallow depression in the sigmoid colon. Tubular adenoma with moderate atypia was diagnosed in the biopsy specimens. One year and nine months later colonoscopy and radiographies revealed a polypoid tumor with a central depression at the same site. Radiographically, the maximum diameter of the lesion had changed from 11 mm to 21 mm. The resected specimens showed moderately differentiated adenocarcinoma invading the propria muscularis. In the other patient, a flat-topped elevation was detected in the lower rectum by colonoscopic examination. The biopsy specimens revealed tubular adenoma with moderate atypia. Five years later colonoscopy showed a flat elevation with a central shallow depression in the lower rectum. The size of the lesion had increased and the converging folds had developed markedly. The resected specimens revealed moderately differentiated adenocarcinoma with submucosal invasion. In the two cases, morphological alterations were observed macroscopically and histologically.