Wilms' Tumor

The Wilms' tumor (WT) is an embryonal tumor of renal origin, but extrarenal localization may rarely occur. The first description of a kidney tumor as myoma sarcomatodes is from Eberth in 1872. In 1898, Birch-Hirschfeld classified a similar kidney tumor as embryonal adenosarcoma. In 1899, Wilms reviewed the literature and added seven more cases with the clinical picture of the tumor that now bears his name, or neph-roblastoma. It is the most common kidney tumor, the second common solid tumor after neuroblastoma, and represents 6–10% of all childhood cancer cases. The incidence varies between 1 per 50.000 to 1 per 200.000 neonates. It is more common in the US with 10.9 per million than in China with 2.5 per million. Most cases are diagnosed around the age of 3 years (range 1–5 years). Males and females are affected equally. Ninety-two to ninety-five percent of the WT occur in only one kidney and are unilateral. Anomalies associated with WT are the WAGR syndrome (aniridia, genitourinary anomalies, mental retardation), the Denis-Drash syndrome (intersex, nephropathy), the Beckwith-Wiedemann syndrome (exomphalos, macroglossia, viscero-megaly), and hemihypertrophy. Patients with bilateral tumor or other associated anomalies are diagnosed signifi cantly earlier. About 2% of patients have a positive family history with one relative who also suffered from a WT. The association with other anomalies as well as the occurrence in families suggest that altered genes are involved in the tumor pathogenesis. Several genetic loci are involved. The two more important genes are the WT 1 and WT 2 suppressor gene on chromosome 11, but additional loci have been described on several other chromosomes, so far.