食道表在癌における炎症を示唆する拡大内視鏡所見─B2血管の鑑別，B2 iの提唱

Magnified Endoscopic Findings which Suggest Inflammation in Superficial Esophageal Squamous Cell Carcinoma:A New Sub-classification of B2 i

要旨●NBI拡大内視鏡で観察される非ループ血管（B2血管）を，血管径が細く高密度の“B2 i”と，それ以外の“B2 pure”へ亜分類し，その特徴を検討した．2011年1月〜2018年5月までに食道ESDを施行した食道扁平上皮癌（SCC）のうち，NBI拡大観察にてB2と診断し，組織像との一対一対応が可能であった連続51例53病変を対象とした．B2 pureを認めた44病変の病理組織学的診断はすべてSCCであった．一方，B2 iを認めた9病変の病理組織学的診断はSCCが2病変のみで，7病変がびらん・炎症であった．また，CD34染色22切片を用いてNBI拡大観察でB2 pureおよびB2 iが観察された領域の，表層から100μmまでの血管短径と密度を計測した．密度平均値は，B2 pureで3.35本/mm，B2 iで8.22本/mmで，B2 iで密度が有意に高かった（p＝0.001）．血管短径平均値は，B2 pureで12.3μm，B2 iで6.65μmで，B2 iは有意に血管径が細かった（p＝0.0028）．血管径と密度の相関をみると，B2 iではより細く高密度であり，B2 pureではより太く低密度であることが示された．B2 iはびらん・炎症の特徴的な拡大所見であり，深達度の深読みを予防しうる重要な指標と思われた．

　Non-loop vessels（type B2）observed using narrow-band imaging magnified endoscopy（NBI-ME）were sub-classified into B2 i as thin vessels with high density and B2 pure as except for B2 i. The characteristics of B2 i and B2 pure were investigated.

　Fifty-three consecutive squamous cell carcinomas（SCC）in 51 patients treated by esophageal ESD from January 2011 to May 2018 enrolled in this retrospective study were assessed. Histological findings of the B2 area diagnosed by NBI-ME were investigated.

　All pathological diagnoses in 44 lesions that exhibited B2 pure were SCC. Pathological diagnoses of the 9 lesions that exhibited B2 i were SCC in 2 lesions and erosion or inflammation in 7 lesions.

　We investigated density and mean diameter of vessels in the regions that exhibited B2 i or B2 pure. Veins that were 100μm from the surface were counted using 22 sections stained by CD34.

　The mean density in B2 pure and B2 i was 3.35/mm and 8.22/mm, respectively（p＝0.001）. The mean minor axis of the vessels was 12.3μm and 6.65μm, respectively.（p＝0.0028）. B2 i has thin and high-density vessels, and B2 pure has thick and low-density vessels.

　B2 i is a characteristic finding of erosion or inflammation. Therefore, B2 i is an important parameter to prevent overdiagnosis of invasion depth.