Prenatal detection of a Wilms' tumor.

Kidney tumors occur very rarely in utero but when present, they are most often congenital mesoblastic nephroma. A newborn boy was transferred to our hospital with a history of fetal renal mass which proved to be a Wilms' tumor. The clinical history, imaging results, and differential diagnosis are presented with a discussion of neonatal Wilms' tumor. While imaging may not specify the exact diagnosis, it provides staging and anatomic information for the surgeon and the oncologist.