Alpha-fetoprotein producing tumor cells in children with Wilms' tumor.

Alpha fetoprotein (AFP) is generally used as a marker in diagnosis and follow-up of germ cell tumors and hepatoblastomas. However, serum AFP levels were elevated in our three patients with Wilms tumor. The elevated levels could only be decreased completely by surgery and not by chemotherapy. Histopathologically, the tumors consisted of blastemal, stromal, and epithelial cells. Chemotherapy was only effective on stromal and epithelial components of the tumors. In AFP staining, the source of AFP production was identified as blastemal tumor cells. Because the increased AFP levels were decreased after surgery, AFP levels may be used in the follow-up of the patients with Wilms tumor. Herein, we report three patients with Wilms tumor whose serum AFP levels were elevated and who had diffuse WT-1 and focal AFP expression in all tumors, immunohistochemically.