2) 胃 (2)血管パターン分類

Classification of the Microvascular Pattern of Early Gastric Cancer

要旨　微小血管と粘膜微細模様の異常を認識することで表在性胃腫瘍のより正確な内視鏡診断が可能であり，real timeのoptical biopsyが可能となってきた．表面陥凹型胃癌の異常微小血管は網目状（network）patternと縮緬状（corkscrew）patternに大別でき，各々分化型腺癌と低分化型腺癌にほぼ対応することから，癌存在診断と同時に組織型予測ができる．表面平坦型胃癌や隆起・陥凹型胃癌の辺縁平坦部では粘膜構造内異常血管（intrastractural irregular vessel；ISIV）がみられる．ISIVは類円形もしくは乳頭状粘膜模様（構造）に内包されるように存在し，口径不同・拡張・形状不均一といった異常形態を呈する微小血管である．表面隆起型胃癌では異常な微小血管は必ずしも出現しないが，粘膜模様の消失・不整化した局面に網目状の異常血管や辺縁部にISIVがみられる．このように，胃癌肉眼型に応じた系統的な微小血管異常を念頭に置くことで，より正確な胃癌拡大内視鏡診断が可能となる．

　The recognition of irregularity of microvessel and fine mucosa structure contributes to accurate endoscopic diagnosis of superficial gastric cancer and allows optical biopsy in real time. Irregular microvessels of superficial depressed gastric cancer are classified into two patterns, ‘network pattern' and ‘corkscrew pattern', which correspond to well-differentiated adenocarcinoma and poorly-differentiated adenocarcinoma respectively. In superficial flat cancer, as well as the marginal flat area of an elevated or a depressed lesion, a specific microvascular pattern called ISIV (intrastractural irregular vessel) is observed. ISIV is a group of microvessels enclosed in a round or papillary fine mucosal structure, which show irregularity such as heterogeneous shape, uneven caliber and abnormal dilatation. Although irregular microvessels are not always visible in superficial elevated cancer, when they are visable patterns of the irregular microvessels are classified into three groups, 1)network-shaped vessels in the area where fine mucosal structure disappears, 2)isolated irregular vessels that transverse or overrun the fine mucosal structures, 3)ISIV as shown above. Magnified endoscopic diagnosis can achieve optical biopsy by accurate understanding of the patterns of irregular microvessels that vary according to the macroscopic appearances (depressed, flat, or elevated) of superficial gastric cancers.

　In this way, Observing classification of microvascular pattern makes it possible to diagnose early gastric cancer by Magnified endoscopy.