除菌後発見胃癌の内視鏡的特徴と病理像─拡大内視鏡像を中心に

Endoscopic Features of Gastric Cancer after Successful Helicobacter pylori Eradication Therapy

要旨●除菌後発見胃癌24例と対照群47例において，通常光観察とNBI拡大内視鏡観察における胃炎様模様と，組織における非腫瘍上皮の被覆の程度について検討した．除菌群で胃炎様模様，非腫瘍上皮の被覆が多くみられた．また，内視鏡像で胃炎様模様を呈する症例の9割以上に組織で非腫瘍上皮の被覆がみられ，癌腺管とモザイク状に混在していた．内視鏡像での胃炎様模様，病理組織像でのモザイク状の混在は除菌後発見胃癌の存在・範囲診断を困難にする要因であるが，背景粘膜とは異なる領域性を有する胃炎様模様に着目し，NBI拡大内視鏡観察で背景粘膜と病変内部の表面構造を詳細に比較し，“形状不均一”や“方向性不同”に注目することで存在・範囲診断をすることは可能である．

　In the present study, we examined gastritis-like appearance using conventional endoscopy and NBI（narrow-band imaging）magnifying endoscopy and the extent to which non-neoplastic epithelium covered cancer in 74 patients with gastric cancer, 27 patients who had undergone H. pylori eradication（eradication group）and 47 patients who had not（control group）. Gastritis-like appearance and overlying non-neoplastic epithelium were more frequently observed in the eradication group. Approximately 90% of cancers showing gastritis-like appearance had non-neoplastic epithelium extending over 10% of the cancerous area, which was mixed with cancerous ducts in a mosaic-like pattern. Although the presence of gastritis-like appearance and non-neoplastic epithelium make it difficult to detect cancer and delineate the cancerous area, close observation enables accurate diagnosis. To diagnose gastric cancer occurring with gastritis-like appearance, it is important to identify slight differences in mucosal patterns from the surrounding area using conventional endoscopy, as well as surface structure exhibiting morphological heterogeneity and direction diversity using NBI magnifying endoscopy.