家族性大腸腺腫症に発生しNBI併用拡大観察により診断可能であった微小早期胃癌の1例

Small Early Gastric Carcinoma with Familiar Adenomatous Polyposis in a Young Patient Diagnosed Accurately by Magnifying NBI, Report of a Case

要旨　患者は20歳代，男性．FAPに対する大腸全摘術後の経過観察中，上部消化管内視鏡検査で，幽門前庭部に径5mmと径3mmの頂部に発赤調軽度陥凹を伴う隆起性病変を認め，5mm大の病変からの生検でGroup5（tub1）と診断した．ESD時の通常内視鏡観察では，3mm大の病変の質的診断は困難であったが，NBI併用拡大内視鏡観察を施行したところ，発赤調軽度陥凹部に一致してdemarcation lineを認め，大小不同の管状から溝状の腺管開口部を呈する表面微細構造と拡張・口径不同・走行異常を伴う微小血管像を認めた．以上の所見をもとに同病変も粘膜内高分化型腺癌と診断し，2病変をESDにて一括切除した．病理診断では両病変とも粘膜内低異型度高分化型管状腺癌であり，完全切除であった．本症例のような微小癌に対しては，生検による影響で内視鏡治療時に指摘困難となる可能性があるため，十分なインフォームドコンセントを得たうえで，生検をできるだけ省略し，NBI併用拡大内視鏡観察による詳細な診断が必要と考える．さらにFAPにおいては，若年者でも胃癌を合併することがあり注意が必要である．

　A male in his twenties with FAP after total colectomy under went conventional endoscopy during surveillance for malignancy. Endoscopy showed two elevated lesions with slightly reddish depressions located in the prepylorus. The biopsy specimens of the larger lesion（A）revealed well-differentiated adenocarcinoma, therefore ESD was recommended. On the day of ESD, conventional endoscopy could not lead to accurate diagnosis for the smaller lesion（B）. But magnifying endoscopy with NBI made it possible to diagnose accurately well-differentiated adenocarcinoma. Magnifying NBI revealed irregular microsurface pattern（papillary/tubular surface pattern in various shapes and sizes）and irregular microvascular pattern with a clear demarcation line corresponding to a slightly depressed area. We performed ESD for both lesions in en-bloc fashion without biopsy examination of this lesion. Histopathologically, both of the tumors were diagnosed as adenocarcinoma（tub1, low）, pM, ly0, v0, pHM0, pVM0, 0IIc, with tumor size being 4mm and 1mm respectively. For a tiny gastric carcinoma as in this case that may disappear because of the effect of biopsy, magnifying NBI endoscopy is very useful to make an accurate diagnosis.