1585 SCIENTIFIC EXHIBIT Pediatric Renal Masses: Wilms Tumor and Beyond 1 Lisa H. Lowe, MD • Bernardo H. Isuani, MD • Richard M. Heller, MD Sharon M. Stein, MD • Joyce E. Johnson, MD • Oscar M. Navarro, MD Marta Hernanz-Schulman, MD A variety of pediatric renal masses may be differentiated from Wilms tumor on the basis of their clinical and imaging features. Wilms tumor is distinguished by vascular invasion and displacement of structures and is bilateral in approximately 10% of cases. Nephroblastomatosis occurs most often in neonates and is characterized by multiple bilateral sub- capsular masses, often associated with Wilms tumors. Renal cell carci- noma is unusual in children except in association with von Hippel– Lindau syndrome and typically occurs in the 2nd decade. Mesoblastic nephroma is the primary consideration in a neonate with a solid renal mass. Multilocular cystic renal tumor is suggested by a large mass with multiple cysts and little solid tissue. Clear cell sarcoma is distinguished by frequent skeletal metastases, and rhabdoid tumor is distinguished by its association with brain neoplasms. Angiomyolipoma frequently contains fat and is associated with tuberous sclerosis. Renal medullary carcinoma occurs in patients with sickle cell trait or hemoglobin SC disease and manifests as an infiltrative mass with metastases. Ossifying renal tumor of infancy is differentiated from mesoblastic nephroma by the presence of ossified elements. Metanephric adenoma lacks specific features but is always well defined. Renal lymphoma is characterized by multiple homogeneous masses, often with associated adenopathy. Index terms: Kidney neoplasms, diagnosis, 81.30 • Kidney neoplasms, in infants and children, 81.30 • Kidney, nephroblastomatosis RadioGraphics 2000; 20:1585–1603 1 From the Departments of Radiology and Radiological Sciences (L.H.L., B.H.I., R.M.H., S.M.S., M.H.S.) and Pathology (J.E.J.), Vanderbilt University Children’s Hospital and Medical Center, D-1120 Medical Center North, 1211 22nd Ave S, Nashville, TN 37232; and the Department of Diagnostic Imaging, Hospital for Sick Children, Toronto, Ontario, Canada (O.M.N.). Presented as a scientific exhibit at the 1999 RSNA sci- entific assembly. Received March 1, 2000; revision requested March 28 and received May 15; accepted May 16. Address correspondence to M.H.S. (e-mail: marta.schulman@mcmail.vanderbilt.edu). © RSNA, 2000 LEARNING OBJECTIVES FOR TEST 4 After reading this article and taking the test, the reader will be able to: ■ Describe a variety of pediatric renal masses. ■ Recognize the fea- tures of these masses at evaluation with various imaging mo- dalities. ■ Correlate the ana- tomic, radiologic, and histopathologic findings in pediatric renal masses. CME FEATURE See accompanying test at http:// www.rsna.org /education /rg_cme.html