除菌後に発見された胃癌におけるNBI拡大内視鏡所見の特徴

Magnifying Narrow-band Imaging of Early Gastric Cancers Detected after Helicobacter pylori Eradication

要旨●除菌後に発見された早期胃癌84症例100病変を検討した．組織学的に，表層部で腺窩上皮様に細胞分化を示す分化型癌25病変は低異型度癌が多く，NBI拡大内視鏡観察を行っても19病変は癌の質的診断が困難であった．辺縁部を中心に表層を非腫瘍性上皮で被覆された27病変は高異型度癌が多く，12病変は質的診断より境界診断が困難であった．NBI拡大内視鏡は最表層の所見を視認するため，これらの病変では表面微細構造が多様性や不規則性に乏しく，除菌後の胃炎粘膜に類似し，明瞭なwhite zoneを認めることから，診断が困難となる．除菌後の胃炎類似病変は，背景粘膜萎縮が軽度の症例に多いため，特に注意深い観察が必要である．

　We evaluated 100 early gastric cancers detected in 84 patients who received successful Helicobacter pylori eradication therapy. Narrow-band imaging with magnifying endoscopy（NBI-ME）findings for gastric cancers after eradication were characterized by homogeneous and regular microstructure bordered by clear“white zone”, resembling the adjacent non-cancerous mucosa. Because NBI-ME is a special modality for enhanced visualization of microstructures within the superficial layer of cancers, such as“gastritis-like”appearance, it correlated with histological surface differentiation and non-neoplastic superficial epithelium. Moreover, surface differentiation revealed cytological maturation at the luminal surface layer of cancers. This finding led to difficulty in a qualitative diagnosis of cancer by NBI-ME（n＝19, Figs. 3 and 4）. Non-neoplastic tubules among and/or on the cancer tubules caused unclear demarcation of cancers (n＝12, Figs. 1 and 2）. To accurately diagnose“gastritis-like”cancers after eradication, careful surveillance endoscopy is recommended, particularly for patients with mild mucosal atrophy.