Aggressive neuroblastoma simulating Wilms tumor

Solid intrarenal neoplasms in children are usually Wilms tumors. Occasionally, however, a neuroblastoma appears to be intrarenal. In six cases where this phenomenon was observed, the histologic findings of each tumor were identical: undifferentiated neuroblastoma. In each case the child's condition rapidly and progressively deteriorated. These six cases demonstrate the possibility that intrarenal origin or extension of neuroblastoma may be confused with Wilms tumor.