胃上皮性腫瘍の拡大観察像と病理学的所見

Verification of the Usefulness of Magnifying Endoscopy with Narrow Band Imaging for Diagnosing Early Gastric Carcinoma from a Pathological Viewpoint

要旨　NBI（narrow band imaging）併用拡大内視鏡観察後に内視鏡的切除された早期胃癌病変を対象に，NBI所見と病理学的所見についてデジタル画像による比較検討を行った．Yagi分類に基づいてNBI拡大観察の所見が評価され，それらを踏まえてKobayashi分類により病変のグループ分類がなされた．A-typeの全例が胃型優位形質を示し（100％，15/15），B-typeでは全例が腸型優位形質を示した（100％，6/6）．一方，C-typeの多くが中分化型腺癌ないし低分化型腺癌を混在し（84.2％，16/19），形質別には胃腸混在型が最多であった（52.6％，10/19）．NBI拡大観察には形質を含めた病理組織所見が反映されると考えられ，腫瘍性変化の認識や質的診断に関して有用性が示された．一方で，表層部が非癌粘膜で被覆される中分化型ないし低分化型腺癌や，一部の特殊な組織型を伴う病変では，所見を取るうえで十分な注意が必要と考えられた．

　The aim of this study was to verify the usefulness ME-NBI（magnifying endoscopy with narrow band imaging）for diagnosing early gastric carcinoma. Formalin-fixed and paraffin-embeded materials were histopathologically evaluated according to Yagi-Kobayashi's classfication of ME-NBI. All lesions of type-A group（100％,15/15）demonstated gastric-dominant phenotype. All lesions of type-B group（100％,6/6）showed intestinal-dominant phenotype. On the other hand, there was a higher frequency of moderately to poorly differentiated carcinoma（84.2％,16/19）and gastrointestinal phenotype ones（52.6％,10/19）in the type-C group.

　The ME-NBI seemed to be useful for diagnosing early gastric carcinoma, but there were some difficult and misleading cases with special histopathological findings such as moderately differentiated carcinoma covered with non-neoplastic epithelium on their surface, which urges us to be careful in diagnosing early gastric carcinomas with ME-NBI.