衝突早期胃癌の1例

Collision Early Gastric Cancers, Report of a Case

要旨　患者は65歳，女性．症状なく，健診の内視鏡検査で胃角のⅡcと診断された．胃X線所見で胃角後壁に結節状隆起と，この病変に接して肛門側に浅い不整陥凹を認めた．側視鏡による所見で，胃角小彎に境界明瞭なⅡcと，これに接して口側に白色の扁平隆起を認めた．なお，胃体中部小彎の発赤したびらんは生検でadenocarcinomaであった．ⅡaとⅡcの衝突癌疑い，胃体部のⅡcとの術前診断で胃切除を行った．切除胃ならびに組織所見は，胃角小彎に5×2cmのⅡc，por1，m，Ul-Ⅱsで，これに接した口側のⅡaに連続して口側にⅡcが広く進展し，胃体部のIlc部位をも含む10×5cmのⅡa＋Ⅱc，tub1，m，Ul-Ⅱs，n（-）（0/20）で，組織像は低異型度小腸型分化型腺癌に相当し，2個の早期癌の衝突を組織学的に診断しえた．早期胃癌の診断にあたって，ⅡaとⅡcの相接する所見と両者の生検所見が明らかに異なる場合には，衝突癌の存在を念頭に置くべきであろう．

　A 65-year-old female was found by endoscopy to have a Ⅱc type cancer on the gastric angle. Further examination using a side‐viewing endoscope revealed that the Ⅱc was 3 cm in size and located on the lesser curvature of the angle a white Ⅱa type cancer was discovered adjacent to the oral side of the Ⅱc, and biopsy findings of these two lesions were different. Furthermore, red erosion was detected on the lesser curvature of the middle body, and biopsy specimen showed it to be cancer.

　The preoperative diagnosis suspected the collision of early cancers and Ⅱc. Surgical specimens showed a Ⅱc type cancer 5×2 cm in size located on the angle. Histologically, a poorly differentiated adenocarcinoma 10×5 cm in size with invasion depth m, along with Ul-Ⅱs and Ⅱa+Ⅱc, had spread widely and superficially to the oral side and was adjoining the Ⅱc. Histologically, the Ⅱa+Ⅱc was a well differentiated adenocarcinoma with invasion depth m, along with Ul-Ⅱs. This histologic figure is similar to differentiated adenocarcinoma with low-grade atypia. Thus the collision of two cancers was diagnosed histologically. There was no lymph node metastasis.

　When trying to diagnose early cancers, the finding of Ⅱa and Ⅱc type lesions adjoining each other, but with clearly different biopsy findings, should be considered as possibly being the collision of early gastric cancers.