Helicobacter pylori未感染早期胃癌・胃腫瘍の拡大内視鏡診断—自験例の検討から

Magnifying Endoscopic Diagnosis of Early Gastric Cancer and Superficial Neoplasm without Helicobacter pylori Infection：A Case Series

要旨●H. pylori（Helicobacter pylori）感染率の低下を背景に，従来まれとされたH. pylori未感染胃癌の存在が注目されるようになった．本稿では2005年4月〜2018年6月の期間に経験したH. pylori未感染早期胃癌のうち，胃底腺領域の超高分化型・低異型度腺癌と胃角部前庭部に局在する胃底腺・幽門腺境界領域の印環細胞癌計40例について，拡大内視鏡所見と病理組織学的所見を対比し特徴を検討した．胃底腺型胃癌や印環細胞癌は最表層を非腫瘍に被蓋され，表面構造と血管構築の不整に基づくdemarcation lineの認識が困難であった．表層に腺窩上皮型胃癌成分を有する病変は病理組織学的所見通り表面構造の不整が軽微であるものが存在した．しかし，いずれも丁寧な拡大観察によりその病理組織像を推定することは可能と考えられた．周囲に萎縮のない胃粘膜にする病変のため，その存在診断自体は困難ではないと思われ，拡大内視鏡診断は質的診断において重要と考える．

　The present study was retrospective and aimed to investigate the magnifying endoscopic appearance of early gastric cancer without H. pylori（Helicobacter pylori）infection from April 2005 to June 2018. We included 40 patients who fulfilled the requirement of not being infected by HP in the diagnosis as well as endoscopic and histological examinations. Of these, 21 patients had very well differentiated adenocarcinomas of the gastric phenotype, whereas 19 had signet-ring cell carcinomas. Fundic gland type adenocarcinomas and signet ring cell carcinomas did not exhibit demarcation lines because their surfaces were covered with the normal foveolar epithelium. In addition, some highly differentiated adenocarcinomas of other gastric phenotypes exhibited only subtle irregularities of surface patterns because of their pathological characteristics. However, we conclude that elaborate magnifying endoscopy could potentially estimate the histopathological structures of such gastric type adenocarcinomas by detecting the subtle surface and vascular abnormalities.