粘膜下層浸潤癌を認めたSPS（serrated polyposis syndrome）の1例

SPS（Serrated Polyposis Syndrome）with Submucosal Invasive Cancer, Report of a Case

要旨●患者は60歳代，女性．上行結腸肝彎曲部に30mm大の発赤の目立つ表面型病変と，それに連続する白色調の平坦隆起を認めた．NBI拡大観察にて，発赤部分は佐野分類CP Type IIIB，クリスタルバイオレット色素撒布内視鏡拡大観察ではV_I高度不整pit（V_I invasive pattern）を呈し，白色調の平坦隆起部は星芒状pitが主体であった．内視鏡的には，HPあるいはSSA/P由来の0-IIa＋IIc型，SM高度浸潤癌と診断し．病理組織学的には，高異型度高分化腺癌がSSA/Pと連続性に認められ，粘膜下層深部まで浸潤していた．BRAF変異およびMLH1メチル化を認め，それに伴うMSI陽性腫瘍であることが確認された．また，その他にも多数の鋸歯状病変を認め，WHO基準よりSPSと診断した．

　A 60-year-old female had a reddish superficial lesion in the ascending colon with surrounding discolored flat elevation. Narrow band imaging magnifying image showed distorted and sparse microvessels within the reddish lesion. Magnification colonoscopy with crystal violet staining demonstrated the reddish superficial lesion to have a type V_I high-grade pit pattern（V_I invasive pattern）with a regular asteroid pit pattern in the surrounding discolored flat elevation. Histologically, the resected specimen revealed well-differentiated adenocarcinoma continuing to sessile serrated adenomas/polyps（SSA/P）and adenocarcinoma with deeper submucosal invasion. The tumor showed BRAF mutations and MLH1 methylation, indicating microsatellite instability. The patient had other multiple SSA/Ps, and hence, we diagnosed the patient with serrated polyposis syndrome using the WHO classification.