リンパ節転移を認めたGISTの1例

Gastrointestinal Stromal Tumor of the Stomach with Metastasis to Lymph Node, Report of a Case

要旨　患者は72歳，男性．主訴は吐血．内視鏡検査および腹部CT検査で，胃噴門部後壁に粘膜下腫瘍を指摘され，胃全摘術を受けた．摘出腫瘍はSkandalakis分類の混合型発育を示す7×6×5cm大の粘膜下腫瘍で，内腔側突出部中央に1.5×1.0cmの不整な下掘れの強い潰瘍を有していた．病理組織学的に腫瘍は，比較的均一な紡錘形細胞の密な束状・柵状の増殖から成り，一部に大型の異型核を有する細胞を伴っていた．腫瘍細胞には50高視野当たり13個の核分裂像がみられ，また，左噴門リンパ節に転移を認めた．腫瘍細胞は免疫組織化学的にはc-kit protein，CD34，および筋原性マーカーのcaldesmonが陽性であった．以上の所見より筆者らの基準に従いgastrointestinal stromal tumor(GIST)，smooth muscle type，malignantと診断した．GISTの肝転移はしばしばみられるが，リンパ節転移を認めた報告は少なく本症例はまれな症例と考えられた．

　A 72-year-old man was seen at the hospital because of hematemesis. Endoscopic examination showed a large submucosal tumor with hemorrhagic ulceration in the cardiac region. Total gastrectomy was performed. The resected tumor was 7×6×5 cm in size. Histopathologically, the tumor was composed of fasciular proliferation of the spindle-shaped cells with mitosis (13/50 HPF). Immunohistochemically, the tumor cells were positive for vimentin, c-kit, CD34 and caldesmon, but negative for a-SMA and S-100. The tumor was diagnosed as malignant GIST, smooth muscle type, with metastasis to the regional lymph nodes. Although matastasis to the liver is commonly seen, this case is reported because the GIST with matastasis to the regional lymph node is very rare.