日本食道学会拡大内視鏡分類と深達度―Type R血管と組織像

Classification of the Japan Esophageal Society for Magnifying Endoscopy and the Depth of Tumor Invasion: Type R Vessels and Histopathological Features

要旨　日本食道学会拡大内視鏡分類の付記1“不規則で細かい網状（reticular：R）血管を認めることがあり，低分化型扁平上皮癌（por SCC），INFc，特殊な組織型を示すことが多いので，Rと付記する”を検証するべく，低分化型，INFc，特殊な組織型を示す病変の血管像を見直し，Type Rの特徴を再検討した．食道表在癌316病巣中，por SCC，特殊な組織型，INFcを示した病変は45病巣あり，このうち16病巣（35.6％）にType Rと判定される血管が観察された．Type Rの特徴として，褪色調の領域を作って血管密度が低いこと，極めて細いチリチリした網状の形態を示すこと，口径不同が著しいこと，loop構造の名残がないことが挙げられた．病理組織像は細かい蜂巣がバラバラに浸潤する病変でType Rを示すことが多く，por SCCやINFc，特殊な組織型を示した病変のうち，浸潤性の病巣が表層に露出している（しかかっている）病変が，Type Rとして認識されていると考えられた．

　To verify that“irregular small-caliber, reticular（Type R）vessels are found in poorly differentiated carcinomas（por SCC）, miscellaneous carcinomas such as basal-cell carcinoma, adenosquamous cell carcinoma, and mucoepidermoid carcinoma, and INFc according to the Japan Esophageal Society classification for magnifying endoscopy, we reassessed the vascular images of lesions showing por SCC, INFc, and miscellaneous carcinomas, to reinvestigate the characteristics of Type R. Among 316 lesions of superficial esophageal cancer, 45 showed por SCC, miscellaneous carcinomas, and INFc patterns, and 16（35.6％）of these lesions showed blood vessels evaluated to be Type R. Type R vessels were characterized by low vascular density in pale regions, extremely fine, curly, reticular features, marked differences in vessel caliber, and no traces of loop structures.

　Histopathologically, lesions showing fine and scattered invasion were often associated with Type R vessels. Among lesions showing por SCC, INFc, and miscellaneous carcinomas, Type R vessels appeared to be associated with infiltrative lesions exposed（nearly exposed）on the superficial layer of the esophagus.