多血症を呈したエリスロポエチン産生腎細胞癌

Erythropoietin-producing renal cell carcinoma with polycythemia：A case report

症例は72歳，男性。他院で多血症を指摘され，精査中に腹部CTで左腎腫瘍を認めたため，当科を紹介された。左腎上極に，造影効果のある長径98mm大の腫瘍を認めた。cT2aN0M0の診断で，根治的左腎摘除術を施行した。病理組織学的に淡明細胞型腎細胞癌と診断された。術前より高値を示した血清エリスロポエチン値は，術後には正常値に回復し，多血症も改善した。術後9か月目に右肺転移を認め，胸腔鏡下右肺部分切除術を施行した。現在，外来でフォロー中である。

The 72-year-old man with left renal tumor detected by computed tomography was referred to our department for the detailed examination of associated polycythemia. Polycythemia disappeared and the serum erythropoietin became decreased after left radical nephrectomy. Histopathologic examination revealed clear cell renal cell carcinoma（G2＞G1＞G3, INFb, v1, ly0, eg, fc1, im0, rc-inf0, rp-inf0, s-inf0, pT2a）. Immunohistochemical study revealed erythropoietin expression in the carcinoma cells. Although post-operative course had been uneventful, development of the nodule in the right lung was observed at 9 postoperative month. Video assisted thoracoscopic surgery was performed and histopathological examination of the resected tumor confirmed metastatic renal cell carcinoma. The patient has remained disease-free to date.