大腸ESDにて治癒切除と判断され，1年後に粘液癌で局所再発した早期大腸癌の1例

Local Recurrence of Intramucosal Cancer in the Rectum after En bloc Complete Resection, Report of a Case

要旨　患者は70歳代，男性．下部直腸に30mm大で丈高の隆起性病変を認めESDを行った．病理結果は，carcinoma in tubulovillous adenoma，M，ly0，v0，HM0，VM0であり治癒切除と判断したが，1年後の経過観察内視鏡で，初回ESDの瘢痕近傍になだらかに立ち上がる15mm大の隆起性病変を認めた．診断目的に再ESDを行ったところ，mucinous adenocarcinoma，SM-M以深，ly0，v0，HM0，VM1と診断された．初回ESD病変の深切り切片を再評価したところリンパ管侵襲を指摘されたため，初回ESD病変の局所再発であると考えた．断端陰性一括切除された深達度Mの早期大腸癌が粘膜下腫瘍様の形態を呈する粘液癌で局所再発した症例は，筆者らが検索しえたかぎりではこれまでに報告がない．絨毛性腫瘍は割を入れると細かく分断され薄く切れないため，脈管侵襲を発見するためには多段階の深切りによる病理学的検索が重要と考える．

　We report a case of local recurrence of intramucosal cancer after en bloc complete resection. We performed colorectal ESD（endoscopic submucosal dissection）for a male patient in his 70s with a protruding tumor, measuring 30mm in the lower rectum. The lesion was histologically diagnosed as carcinoma in tubulovillous adenoma with tumor-free margin and no vessel invasion. However, the follow-up colonoscopy 1year after ESD showed a SMT（submucosal tumor）next to the post-ESD scar. We performed ESD as total biopsy again and diagnosed the lesion as mucinous cancer with submucosal or deeper invasion. To elucidate the cause of the local recurrence, we examined deeply cut sections of the initial lesion and lymphatic invasion was newly found. There is no reported case of a local recurrent lesion composed of mucinous cancer in the shape of SMT after intramucosal cancer has been resected en bloc with tumor-free margin. This case indicates the importance of multiple step cut sections to find out lymphatic invasion, whenever cutting stride cannot be shortened because of villous structures which could be easily destroyed by cutting.