Renal sarcomas of childhood.

Renal sarcomas in infants and children are extremely uncommon. Previously classified as Wilms tumors with unfavorable histology, these tumors were thought to be variants of Wilms tumors but in general have a worse prognosis. Our recent experience with 4 cases of renal sarcomas indicate that these tumors must be approached individually and treated appropriately. Their histologic picture and their varying response to surgery and chemotherapy suggest that these unusual tumors are not variants of Wilms tumors but instead sarcomas unrelated to the classic Wilms tumors.