食道上皮下病変の内視鏡診断—画像強調内視鏡（NBI拡大）の立場から：特に上皮下発育を呈する食道癌を中心に

Diagnosis of Subepithelial Lesions of the Esophagus Using Endoscopy, Focusing on Esophageal Carcinoma with Subepithelial Growth

要旨●上皮下発育を呈する食道癌のNBI拡大内視鏡所見と病理組織学的所見を解析し，その特徴やそれに基づく診断ストラテジーについて検討した．特にSECNに類似した上皮下に存在し蛇行や口径不同，形状不均一などの異常に乏しいネットワーク状血管をSECN-like vesselsと命名し，この血管を呈する隆起性食道癌を対象とした．SECN-like vesselsは病理組織学的には非腫瘍性重層扁平上皮と腫瘍の間に存在する血管であった．腫瘍径や存在部位により2群に分類可能で，関心領域が病変のほぼ全体を占め，大きさが4mm以上の場合（A群）は特殊組織型食道癌，特にNEC，BSC，まれであるがAMを，胃のWGAに類似しSCCの辺縁あるいは中央に存在し，その大きさが1〜2mm程度と小さい場合（B群）は癌胞巣中心の囊胞様変化として異角化細胞，錯角化，泡沫細胞，腫瘍壊死あるいはSCC胞巣を考慮する必要があると考えられた．

　Based on the analysis of the findings of narrow band imaging- magnification endoscopy and histopathology for esophageal carcinoma with subepithelial growth, we discussed the characteristics and diagnostic strategies. The SECN（subepithelial capillary network）-like vessels were defined as slightly dilated SECN that were not heterogeneous in shape, caliber, or tortuosity, and they were located between the nonneoplastic stratified squamous epithelium and the tumor. The lesions can be classified into two groups based on the size and location of the region of interest：1）esophageal carcinomas that occupy almost the entire lesion and is >4mm and belong to special and rare histological types, especially neuroendocrine carcinoma, basaloid squamous cell carcinoma, and AM（group A）and 2）carcinomas that small and resemble the gastric white globe appearance and are present at the margins or in the center of the SCC（squamous cell carcinoma）（group B）, in which case, it is necessary to consider dyskeratosis, parakeratosis, foamy macrophages, tumor necrosis, or SCC cell nests that are present in the voids of the cancer cells.