内視鏡的に深達度mと診断してEMRが施行されたⅠsp型大腸sm癌の1例

Type-Ⅰsp Submucosal Colon Cancer which, as Regards Cancerous Depth, was Diagnosed by Endoscopy as Mucosal Cancer, Resulting in Treatment by EMR, Report of a Case

要旨　便潜血陽性が契機となって発見された大きさ約10mmの直腸のⅠsp型病変で，注腸X線検査では側面像の弧状変形から深達度sm₂と診断された．大腸内視鏡検査では病変は中央部のやや深い切れ込みによって分葉状を呈していたが，緊満感もなく表面の凹凸も目立たず，sm癌を示唆する所見は明らかではなかった．また拡大内視鏡観察でも表面構造は主にⅢlないしⅣ型pit patternから成り，中央部の切れ込みの部分でやや不整なⅢl＋Ⅲs型の密在を認めるのみで，深達度mの早期癌と診断し，EMRを施行した．病理組織所見では，腫瘍の表層は高分化腺癌に覆われていたが，中央の切れ込みの部分で低分化腺癌に変化し粘膜下層の中層まで浸潤していた．注腸X線検査では深達度を正診したが，内視鏡で浅く読みすぎたため治療法を誤った大腸sm癌の1例を報告した．

　An incidental positive occult blood test provided the occasion for the detection of a rectal lesion, Ⅰsp in shape and 10 mm in size. It was diagnosed as sm₂ by barium enema in terms of ‘arc deformity'. In contrast to this, endoscopic examination indicated the lesion to be m cancer, because no definite findings indicative of sm invasion were discernible. Upon close endoscopic scrutiny, the lesion was seen to be segmented owing to the central incisure which was quite noticeable but not necessarily implying sm invasion, because neither expansive growth nor unevenness on the surface was recognized. Furthermore through magnifying endoscopy, the surface structure was shown to comprise pit patterns of Ⅲl or Ⅳ. In the central incisure portion only, somewhat irregular-shaped Ⅲl ＋ Ⅲs pit pattern was densely distributed, which led to the endoscopic diagnosis of m cancer. Histopathologically, the surface of the tumor was composed of well-differentiated tubular. adenocarcinoma while, in the central portion of the incisure, it was poorly differentiated cancer, the cancerous invasion of which was as far as the middle of the submucosal layer.

　A case of sm colon cancer, correctly diagnosed by barium enema with cancerous depth and misinterpreted through endoscopy as shallower than it actually was received wrong treatment.