[A case of erythropoietin-producing renal cell carcinoma proved by immunohistochemistry].

A case of erythropoietin-producing renal cell carcinoma is reported. A 59-year-old woman was referred to our hospital for further examination of erythrocytosis accompanied with an elevated serum erythropoietin level. Ultrasonography and computerized tomography scan showed a left renal tumor. She underwent a left radical nephrectomy. Postoperatively, serum erythropoietin level and erythrocytosis were normalized. Histopathology was renal cell carcinoma, clear cell subtype, and immunohistochemistry revealed erythropoietin in cancer cells. Furthermore, the cancerous tissue contained a high concentration of erythropoietin.