純粋Ⅱb型早期胃癌の病理

A Histopathological Study on the Typical Type IIb Early Gastric Carcinoma

要旨　（1）肉眼的に判断される純粋Ⅱb，類似Ⅱb，Ⅱc，Ⅱaと周囲粘膜との高低差を測定し，胃小区間溝の深さ，肉眼的には認識できない胃小窩，および萎縮性胃炎で粘膜表面の粗ぞうとして辛うじて認識できる開大した胃小窩の深さとを対比した．純粋Ⅱbは開大した胃小窩と，Ⅱc，Ⅱaは胃小区間溝とほぼ似通った値を示し，それぞれ0.1mm前後，0.2mm前後であった．0.1mm以下の段差は肉眼的に認識し難いと考えられた．（2）大きさは5mm以下から数cmのものまで存在し，胃液酸度は全体に低く，特に大きなⅡbに低い傾向があった．小さいⅡbは胃全体に散在し，大きいⅡbはM・C領域に局在していた．小さいⅡbは発癌初期像を示すと思われるが，いずれ他の型に変わるものも含まれている可能性がある．大きなⅡbは粘膜内側方浸潤を示し，かつ胃酸などによる変化を受け難い状況にある癌と考えられた．（3）組織型は分化型が多く（82.8％），低分化型はほとんどが随伴例であった．分化型は癌が粘膜全層を占めているが極めて分化の高いものか，あるいは異型が強いものは全層を占めないものであり，癌は表面に露出し，実体顕微鏡では指状，網目状，平坦状などの形態を示した．低分化型では表面は被蓋上皮に覆われ，癌は粘膜上層を浸潤し，固有腺の残存がみられ，実体顕微鏡では粘膜模様が浮腫状，やや粗大で，軽度の配列の乱れとして捉えられた．

　Twenty-three cases of the type IIb gastric carcinoma were reviewed regarding some issues on the definition, the significance and the factors to form IIb lesion. Although the type IIb is defined as the type of carcinoma that has macroscopically the same height as the surrounding mucosa, the difference of less than 0.1mm should be allowed because of the inability to discriminate such a level of difference macroscopically.

　The sizes of lesions varied from 1mm to 75 mm in diameter. Acidity of gastric juice was low especially in the cases with larger Iesion. The smaller lesions most of which were detected in the resected stomach coexisted with other types of carcinoma. The larger lesions detected clinically were located in the middle or upper part of the stomach. It was speculated that the larger Iesion resulted from the intramucosal spread (horizontally) of carcinoma under the circumstance of hypoacidity, and that the smaller lesion signified the incipient phase of carcinoma.

　Differentiated adenocarcinoma was seen with high frequency (82.8%). On histological and dissecting microscopical examination of typical IIb, differences between differentiated and undifferentiated carcinoma were found in the histological construction and the structure of the surface. In the differentiated carcinoma, atypisln was extremely low when it occupied the whole thickness of mucosa, while in case of higher atypism did not occupy the whole mucosa. When exposed to the surface, carcinoma showed various patterns of structure described as finger-like, network or flat. Before the exposure, the carcinoma with the epithelium on it and the gastric glands in it with undifferentiated type appeared slightly edematous and irregular compared with the normal mucosa around it.