•Angiography may be indicated in bilateral nephroblastoma but is rarely done because of MRI imaging being adequate for staging and surgical planning

•Radioisotope scans and/or skeletal survey in patients with suspected skeletal metastases

•Central nervous system (CNS) MRI in patients with clear-cell sarcoma or rhabdoid kidney sarcoma

11.8Differential Diagnosis

•Multicystic kidney, hydronephrosis, cystic nephroma

•Renal abscess

•Cyst of ductus choledochus or mesenteric cyst

•Neuroblastoma, rhabdomyosarcoma, hepatoblastoma

•Other solid tumors in retroperitoneal area

•In neonates: congenital, mesoblastic nephroma (fetal hamartoma)

•Lymphoma of the kidney (rare)

•Renal cell carcinoma

•Extrarenal fibrosarcoma

11.9Staging

National Wilms Tumor Study Group staging system

Stage Description

ITumor confined to the kidney and completely resected. No penetration of the renal capsule or involvement of renal sinus vessels

IITumor extends beyond the kidney but is completely resected (none at margins; no lymph nodes). At least one of the following has occurred: (a) penetration of the renal capsule, (b) invasion of the renal sinus vessels, (c) biopsy of tumor before removal, (d) spillage of tumor locally during removal

IIIGross or microscopic residual tumor remains postoperatively, including inoperable tumor, tumor at surgical margins, tumor spillage involving peritoneal surfaces, regional lymph node metastases, or transected tumor thrombus

11.10 Therapy

•Due to Wilms tumor study groups, the prognosis has changed from a 90% lethality rate to a 90% cure rate

–International differences in treatment procedure:

°Europe (SIOP): Prenephrectomy chemotherapy with less tumor rupture during surgery (from 25% to 8% with prechemotherapy)

°USA (COP): surgery at diagnosis with more accurate tumor staging