Alpha-fetoprotein producing renal cell carcinoma: a case report.

We report a case of alpha-fetoprotein (AFP) producing renal cell carcinoma. A 53-year-old man with fever was found to have a left renal mass on computed tomography. No mass was detected in the liver. Serum AFP was 1,460 ng/ml. Radical nephrectomy showed a 10 cm mass in the upper half. A half of the tumor was whitish yellow and firm whereas another half was soft and bright yellow with hemorrhagic and necrotic areas. Histologically, the two areas were different. The lower part consisted of the clear cell renal cell carcinoma and the upper part consisted of granular cells. On immunohistochemistry, the granular tumor cells only were positive for AFP. Serum AFP level dropped abruptly to 383 ng/ml on the 6th postoperative day and gradually returned to normal during the 6 months. Multiple metastatic nodules were found in the lungs, liver and bone in 9th postoperative month and the AFP was less than 1 ng/ml. This suggest metastatic lesions are non-AFP producing clear cell type. It can be concluded that serum AFP elevation was due to synthesis by the renal cell carcinoma in the absence of liver neoplasm. Although AFP producing renal cell carcinoma is a rare entity, serum AFP can be a useful marker for the detection of the tumor.