Intrarenal neuroblastoma masquerading as Wilms' tumor

Objectives. To better characterize intrarenal neuroblastoma. Methods. We retrospectively reviewed the records of 5 children with neuroblastoma initially diagnosed as Wilms' tumor. Results. Five patients, aged 11 months to 3.5 years, were preoperatively diagnosed as having intrarenal Wilms' tumor, prior to operative or histopathologic diagnosis of neuroblastoma. In 3 children the diagnosis of neuroblastoma involving the kidney was confirmed; in the fourth child subcutaneous metastatic disease precluded biopsy confirmation of the intrarenal tumor; and in the fifth child the kidney was severely displaced but not actually involved by neuroblastoma. All patients were hypertensive and 4 patients had elevated urinary catechol levels. Molecular genetic studies showed N-myc amplification in both patients who were evaluated. All patients had poorly differentiated histopathology. One patient is presently alive at 8 months with recurrent disease and another patient is free of disease 13 years after diagnosis. The remaining 3 patients died of the malignancy. Conclusions. Intrarenal neuroblastoma is a rare entity that clinically and radiographically may resemble Wilms' tumor. Our limited experience indicates that intrarenal neuroblastoma is an aggressive malignancy, and long-term survival is rare.