Spurious polycythemia and renal malignancy

We have described a 19-year-old woman with polycythemia. Based on a normal red cell mass and decreased plasma volume, spurious polycythemia was diagnosed. CT scan of the abdomen revealed a 4 cm mass in the right kidney. Upon right nephrectomy, the mass was found to be an unusual neoplasm of the renal tubular epithelium. Four weeks postoperatively, both the hemoglobin and hematocrit values were normal.