組織混在型早期胃癌の内視鏡的特徴―拡大内視鏡

Magnified Endoscopic Findings of Early Gastric Cancers Mixed with Well and Poorly Differentiated Type

要旨　2012年1月～2月までの間に，ESDを施行した胃癌172例182病変を対象とし，肉眼系別に組織型と内視鏡所見の相関を検討した．主肉眼型は0-I型：9，0-IIa型：67，0-IIb型：7，0-IIc型：99病変であった．組織型はtub1，tub2，papを分化型，por，sig，mucを未分化型とし，純粋分化型，純粋未分化型，混在型の3群に分けた．また，混在型を分化混在型と未分化混在型に二分した．0-I型癌9病変中，2病変に未分化型癌の混在を認めた．2病変ともpap成分を有する0-I型癌であり，pap成分を有する0-I型癌は未分化混在を念頭に置く必要があると推察された．0-IIa型癌67病変中，18病変が混在型であり，このうち4病変が未分化混在型であった．腫瘍径が30mmを超えると，分化混在型や未分化混在型の頻度が増加していた．0-IIb型癌7病変中，1病変が分化混在型であったが，未分化型混在型は認められなかった．0-IIc型癌99病変中，42病変に混在型が認められ，17病変が未分化混在型であった．腫瘍径とともに分化混在型や未分化混在型の頻度が増加し，特に30mmを超えると，50％が未分化混在型であった．また，大きさにかかわらず，未分化混在型はすべてtub2成分を有していた．拡大内視鏡観察にて，表面構造の不明瞭化や，non-network血管が観察された場合は，未分化混在型の術前診断が可能であった．しかし，大きな病変全体を拡大観察することは困難であり，拡大内視鏡による組織混在型癌の診断には課題が残された．

　One hundred eighty-two gastric adenocarcinomas from 172 patients treated by ESD from January to December, 2012 were enrolled in this study. The gross type was classified into 0-I, IIa, IIb and IIc, and the numbers were 9, 66, 8, and 99, respectively. The histology was classified into tub1, tub2, pap, por, sig and muc. When the cancer had only tub1, tub2, or pap component, it was classified as pure differentiated type. And, when the cancer had tub1 and pap component, it was classified as mixed type. And, when the cancer had a poorly differentiated component, it was classified as poorly mixed type.

　Two of 9 0-I cancers were classified as poorly mixed type. Both of them had pap component. And remaining 7 cancers were pure well-differentiated type.

　Eighteen of 67 0-IIa cancers were classified as mixed type, and 4 of them were poorly mixed type. The frequency of poorly mixed type was higher when the size became 30mm or more.

　One of 7 0-IIb was mixed type. But, there were no poorly mixed types.

　On the other hand, 42 of 99 0-IIc cancers were mixed type, and 17 cancers had por component. The frequency of poorly mixed type has increased with the size. And, the ratio of poorly mixed type increased to 50％, when the size became 30mm or more.

　Magnified endoscopy is a useful device for the diagnosis of the histology. For example, when uncertain surface or non-network vascular pattern was observed, the cancer could be diagnosed as poorly differentiated type. However, the disadvantage of magnified endoscopy is the narrow observation field and contact bleeding. Detailed observation from the edge to the edge by a magnified endoscopy is impossible, because the width of the visual field is only 3mm. Therefore, a combination of white light endoscopy and NBI magnified endoscopy is necessary.