A teratoid Wilms' tumor with raised serum alpha-fetoprotein level.

Tumor markers are used to diagnose certain cancers and can be useful in monitoring the response to treatment. We describe a renal tumor with the features of a teratoid nephroblastoma associated with a raised serum level of alpha-fetoprotein (AFP). The serum AFP remained high during chemotherapy but returned to normal after nephrectomy. AFP was demonstrated by immunohistochemistry in cysts lined by enteric-type epithelium within the tumor. Cytogenetic examination of the tumor showed a clone of cells with trisomy 8. Raised serum AFP has not previously been described in teratoid Wilms' tumor.