表在型食道類基底細胞癌の内視鏡診断—病理学的根拠を踏まえ

Endoscopic Diagnosis of Superficial Basaloid Squamous Carcinoma of the Esophagus：Pathology Based Assessment

要旨●2003年12月〜2016年2月までに内視鏡的切除術を施行した表在型食道類基底細胞癌（basaloid squamous carcinoma ; BSC）10例を対象とした．BSCのみで構成された病変（pure BSC）は2例で表層は非腫瘍で被覆されており，ともにT1a-LPMであった．BSCとSCCとの混在した病変（mixed BSC）は8例で，うち7例でBSCが最深部であり，T1a-MM以深であった．1例ではBSCが露出していた．WLIの特徴としてSMT様隆起，なだらかな辺縁隆起，黄色調顆粒が挙げられ，これらの特徴は8例80%に認められた．NBI-MEではpure BSCでJES Type B2を認め，菲薄化した非腫瘍上皮を通してBSC内の血管が透見されたと考えられた．mixed BSCでは表層がSCC（T1a-EP〜LPM）で被覆されている部位でJES Type B1，JES Type B2を認め，表層を覆うSCCを反映していると考えられた．

　This study comprised 10 patients with superficial basaloid squamous carcinoma（BSC）of the esophagus who underwent endoscopic resection between December 2003 and February 2016. Two patients had lesions consisting BSC alone（pure BSC）, covered by non-neoplastic epithelium ; the lesions in both these patients were T1a-LPM. Eight patients had lesions comprising BSC and squamous cell carcinoma（SCC）（mixed BSC） ; of these patients, seven had BSC in the deepest part, with T1a-MM or deeper, and one patient had an exposed BSC.

　In eight patients（80%）, lesion characteristics observed using white-light imaging included submucosal tumor（SMT）-like protrusions, protrusions with gently sloping margins, and yellowish granules.

　Using narrow-band imaging magnification, we observed Japan esophageal society classification（JES）type B2 in patients with pure BSC. The vascular pattern within BSC was observed through the thin non-neoplasia epithelium. In patients with mixed BSC, at the site of the superficial layer covered by SCC（T1a-EP〜LPM）, both JES type B1 and JES type B2 were observed, which were perceived to reflect SCC covering the superficial layer.

　A new finding of yellowish granules was found in this study.