胃未分化癌の組織発生

Histogenesis of Undifferentiated Gastric Carcinoma

要旨●胃未分化癌は，Ueyamaらが報告したvimentin陽性胃癌に始まる極めて予後不良な退形成癌である．vimentin陽性胃癌は，充実・髄様に発育した癌で，円形〜多形を示し好酸性あるいは淡明な細胞質と偏在した核から成るラブドイド細胞に似た腫瘍細胞（rhabdoid-like cell）を含むことを特徴とする．また近年，胃未分化癌や充実型低分化胃癌ではクロマチンリモデリング因子であるSWI/SNF（BAF）複合体の構成蛋白（SMARC蛋白）やARID1A蛋白の欠失を伴い，高率にマイクロサテライト不安定性（MSI）を示すとの報告もあり，SWI/SNF（BAF）複合体の失活は胃癌の充実型組織発生に関与すると考えられる．

　Undifferentiated gastric carcinoma, which was previously identified as vimentin-positive gastric carcinoma by Ueyama et al., is an anaplastic carcinoma with a poor prognosis. Vimentin-positive gastric carcinoma is characterized by solid or medullary growth, including a “rhabdoid-like cell” having eosinophilic or clear abundant cytoplasm, eccentric nuclei, and prominent nucleoli that mimics the rhabdomyosarcoma cell. Recently, there have been several reports on SMARC protein-loss gastric carcinoma. In these reports, the SMARC protein is said to be composed of the chromatin remodeling factor SWI/SNF（BAF）complex, and loss of function of the SWI/SNF（BAF）complex is highly associated with solid histogenesis of gastric carcinoma and MSI（microsatellite instability）. SMARC protein-loss is associated with the histogenesis of gastric undifferentiated carcinoma.