Ⅰsp・Ⅰp型大腸sm癌の深達度診断―通常内視鏡および超音波内視鏡を中心に

Diagnostic Usefulness of Ordinary Endoscopy and Endoscopic Ultrasonography for Determining the Extent of Submucosal Invasion of Early Colorectal Cancer of the Protruded Pedunculated (Ⅰp) Type and the Protruded Semipedunculated (Ⅰsp) Type

要旨　Ⅰsp・Ⅰp型早期大腸癌の深達度診断について通常内視鏡とEUSの立場から当科の成績をもとに肉眼型別に概説した．Ⅰsp型の通常内視鏡によるsm_2,3の深達度診断の指標を表面性状より模索したが，びらん・潰瘍などの所見だけでは指標にならなかった．また内視鏡的伸展不良所見の検討ではⅠsp型のsm_2,3で出現したものは7病変中1病変のみであった．この理由はⅠsp型病変では深達度sm_2,3でも筋層付近まで大量に癌が浸潤していなければ可動性が残り，伸展不良所見を判断することが難しいためと考えられた．EUSによる深達度診断ではⅠsp型は隆起の頭部まで挙上したsm層の形態を描出することが大切で，良好に描出しえた場合にかぎり有用な補助診断となりうると考えられた．Ⅰp型の通常内視鏡による深達度診断でも，表面性状のびらん・潰瘍はm，sm₁でも少なからず認められ診断の指標にならなかった．伸展不良所見はpenis like型の茎を呈した1病変のみが茎の柔軟性の欠如として判定できた．茎の形態でもpenis型を呈していればsm_2,3と診断できるが，頻度は少なく他の茎の形態は診断の指標にならなかった．EUSによる深達度診断では茎から頭部への連続したsm層の描出が重要であると考えたが，その描出は極めて難しかった．そのため診断率は低率でⅠp型に対するEUSの有用性は低いと考えられた．つまり，Ⅰsp・Ⅰp型癌のsm_2,3浸潤を診断する内視鏡的なよい指標は少なく，EUSも困難である．よって現時点では，診断に迷えばEMR後の病理診断でその後の治療を決定することが現実的であると考えられた．

　Making a precise diagnosis of massive submucosal invasion of early colorectal carcinoma is important for indicating the proper curative treatment such as endoscopic resection or surgical resection with lymph node dissection. We investigated a useful finding for predicting the massive invasion of early colorectal cancers into the submucosal layer by reviewing ordinary endoscopic pictures and endoscopic ultrasonographic (EUS) views.

　As for submucosal cancers of Ⅰsp type, ordinary endoscopic findings showed little specific evidence which could be a reliable sign for making a diagnosis of massive submucosal invasion. On the other hand, the most characteristic finding of EUS for submucosal invasion by a carcinoma was the lifting of the submucosal layer towards the elevated carcinomatous part.

　As for submucosal cancers of Ip type, the only useful finding by ordinary endoscopy was a penis-like thickening and a certain inflexibility of the stalk of the carcinoma caused by submucosal invasion of the carcinoma. However, this phenomenon was detected only in one case. The characteristic finding of EUS indicative of submucosal invasion was also the lifting or elevation of the submucosal layer towards the elevation carcinomatous part, but this finding was hardly visualized by the EUS method.

　In conclusion, there were few characteristic findings, which could be useful for indicating the submucosal massive invasion of early colorectal carcinomas of Ⅰsp and Ⅰp type. Therefore, in the case of early colorectal cancers of Ⅰsp and Ⅰp type, whose depth of invasion is difficult to determine, endscopic mucosal resection and careful pathological investigation of the resected specimen is the only practical procedure for making a precise diagnosis and determining the suitable therapeutic strategy.