Practice Essentials
Wilms tumor, or nephroblastoma, is the most common childhood abdominal malignancy. The median age at diagnosis of this kidney tumor (see the image below) is approximately 3.5 years. With current multimodality therapy, approximately 80-90% of children with a diagnosis of Wilms tumor survive.
CT scan of child with a stage IV Wilms tumor with favorable histology. Note the bilateral pulmonary metastases.
See Wilms Tumor: A Pediatric Oncology Success Story, a Critical Images slideshow, to help identify the clinical features, staging evaluation, prognostic factors, and therapeutic options for this disease.
Signs and symptoms
Clinical findings include the following:
Asymptomatic abdominal mass (in 80% of children at presentation)
Abdominal pain or hematuria (25%)
Urinary tract infection and varicocele (less common)
Hypertension, gross hematuria, and fever (5-30%)
Hypotension, anemia, and fever (from hemorrhage into the tumor; uncommon)
Respiratory symptoms related to lung metastases (in patients with advanced disease; rare)
See Presentation for more detail.
Diagnosis
The following laboratory studies are indicated:
Complete blood cell (CBC) count
Chemistry profile – Including kidney function tests and routine measurements of electrolytes and calcium
Urinalysis
Coagulation studies
Cytogenetics studies, including 1p and 16q deletion
Imaging studies are as follows:
Renal ultrasonography (often the initial study)
Four-field chest radiography (to detect lung metastases)
Abdominal and chest computed tomography (CT)
Abdominal magnetic resonance imaging (MRI)
Histologic confirmation in North America is with immediate nephrectomy, with exploration of the contralateral kidney to ensure that the disease is unilateral, and lymph node biopsy sampling for staging purposes. Immediate nephrectomy is not performed in patients with bilateral disease at presentation.
Approximately 90% of all Wilms tumors have favorable histology; however, 3-7% of Wilms tumors are characterized by anaplastic changes. If these changes are present diffusely throughout the tumor, they are predictive of a poor outcome. Wilms tumors with anaplastic changes have unfavorable histology.
See Workup for more detail.
Management
The usual approach is surgery (nephrectomy) followed by chemotherapy, with or without postoperative radiotherapy. Chemotherapy regimens typically comprise vincristine and dactinomycin; doxorubicin and then cyclophosphamide and etoposide are added for increasingly high-risk disease. Children with loss of heterozygosity at 1p and 16q receive more aggressive chemotherapy.
See Treatment and Medication for more detail.