light blue crest陽性の小腸型低異型度分化型胃癌（狭義の横這型胃癌）の1例

Low-grade, Well-differentiated Adenocarcinoma of the Small Intestinal ("Crawling-type" Adenocarcinoma) with Light Blue Crest, Report of a Case

要旨●患者は50歳代，男性．EGDで胃体下部後壁に10mm大の発赤調平坦病変を認め，生検で胃癌が疑われた．NBI併用拡大観察で，腫瘍部で目立つLBC（light blue crest）により背景粘膜との境界を認め，軽微な不整を示す表面微細構造および微小血管構築像の所見が，小腸型低異型度分化型胃癌に相当する所見と考えESDを施行した．切除標本結果は11×7mm，tub2，pT1a（M）の小腸型低異型度分化型胃癌（狭義の横這型胃癌）であった．NBI併用拡大観察により小腸型低異型度分化型胃癌（狭義の横這型胃癌）の特徴を描出しえたと考えられた．

　Upper gastrointestinal endoscopy performed on a man in his 50s revealed a reddish flat lesion, 10mm in diameter, on the posterior wall of the lower gastric body. A biopsy was performed on the lesion, and the man was diagnosed with adenocarcinoma. Using ME-NBI（magnifying endoscopy with narrow band imaging）, LBC（light-blue crest）was detected in the tumor but not in the surrounding mucosa. LBC was used as a demarcation line between the tumor and the surrounding mucosa. ME-NBI also revealed slightly irregular microvascular architecture and microsurface structure. These endoscopic findings suggested that the tumor was a type of low-grade, well-differentiated adenocarcinoma of the small intestinal ("crawling-type" adenocarcinoma). The surgeon performed an endoscopic submucosal dissection for histological assessment, and the results confirmed the findings of ME-NBI. We believe that ME-NBI used in this case was able to aid clear visualization of the features of this type of adenocarcinoma.