胃粘膜の拡大観察―微小血管構築像を指標とした分化型早期胃癌の境界診断

The Usefulness of Microvascular Findings as Visualized by Magnifying Endoscopy for Determining the Margin of Gastric Cancer of the Differentiated-type

要旨　近年，胃癌の縮小治療法が進歩し，より厳密な分化型早期胃癌の境界診断法が求められている．一方，従来の診断学では癌の境界診断が困難な境界不明瞭な早期胃癌が増加していることが指摘されている，われわれは2000年よりルーチン検査で使用できる拡大内視鏡を用い，早期胃癌の微小血管構築像の特徴像を報告してきた．特に分化型癌の微小血管構築像は特徴的であった．それらは，(1)regular subepithelial capillary network patternの消失，(2)demarcation lineの存在，(3)irregular microvascular patternの存在の3所見であった．これらの所見を用い，拡大観察で癌の境界部を同定し，従来の指標では範囲診断が困難な例を含め分化型癌の浸潤範囲診断に応用している．癌の微小血管構築の拡大観察が境界診断に有用であった分化型粘膜内胃癌の2症例を呈示し，文献的考察を加えた．近年増加した境界不明瞭な癌の特徴は分化型癌で，陥凹や小区像などの所見に乏しく，従来の診断体系では境界診断が困難な例が多く，本論文で示したような微小血管構築を指標とした拡大内視鏡は，癌の境界診断に有用な新しい診断法であると考えられた．

　The preoperative diagnosis of the horizontal extent of an early gastric cancer is essential for carrying out minimal invasive surgery and endoscopic mucosal resection. These days, there is a considerable incidence of differentiated-type gastric cancer presenting an unclear margin, which cannot be identified by ordinary endoscopic technique alone. We reported the characteristic findings concerning the microvascular architecture of early gastric cancer as visualized by magnifying endoscopy. The characteristics of the microvascular architecture in intramucosal gastric cancer, (differentiated-type carcinoma) were an irregular microvascular pattern, the presence of a demarcation line and the disappearance of the regular subepithelial capillary network (SECN) pattern. On the other hand, undifferentiated-type carcinoma presents the disappearance of, or a reduced pattern of the regular SECN. The findings of differentiated-type carcinoma seemed to be specific enough for determining the margin of the carcinoma and for making a differential diagnosis between carcinoma and gastritis in the case of flat reddened lesions. We showed two representative cases in this article. In these cases, the margin of the lesions could be identified successfully by applying magnified endoscopy according to the difference in microvascular architecture between cancerous and non-cancerous mucosa. We are utilizing this technique for preoperative diagnosis to determine the horizontal extent of carcinoma in clinical practice. The margins of all the early gastric cancer of differentiated type became visible after magnification and were successfully identified. The magnified endoscopic technique based on the difference in microvascular architecture and density between cancerous and non-cancerous mucosa could become a new diagnostic system for determining the margins of early gastric cancer.