Alpha-fetoprotein-producing renal cell carcinoma.

A case of alpha-fetoprotein (AFP)-producing renal cell carcinoma with multiple bone and lung metastases, but without liver involvement is reported. The stain specific to AFP (avidin-biotin complex) proved the presence of the AFP in the cytoplasms of some cells of the renal tumors. In addition, three other cases of AFF-producing renal cancer recently published in the literature in Japan are reviewed. These four cases indicate that mesoderm-originating malignant tumors such as renal cell carcinomas can produce AFP in some situations. So, AFP is probably more universal than believed, although it is generally a popular and useful tumor marker for hepatocellular carcinomas and yolk sac tumors. The knowledge of the presence of AFP-producing renal cell carcinomas will make a new contribution to the study of the oncogenesis of AFP-producing tumors.