日本食道学会拡大内視鏡分類と深達度―深達度診断におけるB2血管の意義

Prospective Study of the Usefulness of Type B2 Vessel Determined by the Japan Esophageal Society Classification of Magnified Endoscopy for the Diagnosis of Superficial Esophageal Squamous Cell Carcinoma

要旨　日本食道学会分類B2血管の深達度正診率につき，prospectiveな検討を行った．2年4か月の期間にB2血管と診断した35病変を対象とした．関心領域での病理組織学的深達度は，pT1a-EP/LPMが3病変，pT1a-MM，pT1b-SM1が23病変，pT1b-SM2が9病変であった．AVA-largeを呈したpT1b-SM2の1病変を含め，その正診割合は68.6％（24/35）であった．また，特異度は94.1％と高いが，感度は75.0％とやや低い傾向にあった．誤診例には，ループ形成に乏しい血管の判断が難しい症例，B2血管と判断しても血管径が細い症例や領域が小さい症例が存在し，今後はこれらの所見と深達度の関連を詳細に検討する必要がある．さらに現在この分類の正診率に関して多施設共同前向き研究を開始している．

　The accuracy of the diagnosis of invasion depth in superficial esophageal SCC（squamous cell carcinoma）was evaluated by Type B2 microvessel in a new classification established by JES（the Japan Esophageal Society）at our institute, prospectively. Thirty five consecutive patients who had superficial esophageal SCC showing Type B2 microvessel and treated by ESD（endoscopic submucosal dissection）were enrolled in this study from March 2011 to June 2013. Three lesions were histological diagnosed as pT1a-EP/LPM, 23 lesions were defined as tumor depth of pT1a-MM or pT1b-SM1, and the remaining 9 lesions were determined as pT1b-SM2. The accuracy rate of the tumor depth of invasion on the targeted area diagnosed as Type B2 vessels by magnified endoscopy with NBI（narrow band imaging）was 68.6％（24/35）. The specificity and the sensitivity of Type B2 vessel was 94.1％and 75.0％, respectively. The reason of misdiagnosis was that it was difficult to determine if the microvessel resemble loop form or not and if the variation of diameter or regional area of Type B2 vessel existed. So an investigation in detail was thought to be needed according to the relation between these findings and the tumor depth of invasion.

　In the near future, a prospective multicenter study of the usefulness of JES Classification of magnified endoscopy for the diagnosis of superficial esophageal SCC will be commenced.