Studies on alpha-fetoprotein produced by renal cell carcinoma.

A 58-year-old man was found to have a Stage IV primary renal cell carcinoma (RCC) invading the colon and producing alpha-fetoprotein (AFP). The preoperative serum AFP level of 418 ng/ml had decreased to the normal level of 0.9 ng/ml 3 weeks after the radical operation. As the high serum AFP level in RCC without metastasis to the liver is a rare condition, histopathologic studies were performed on surgical specimens. Histologically, the tumor was clear cell adenocarcinoma and AFP was detected in tumor cells immunohistochemically. A Concanavalin A (Con A) sepharose affinity chromatogram was performed to detect the component of AFP in this case. The Con A nonreactive fraction rate was as high as 47%, which indicated that the AFP of this RCC was of fetal type.