Wilms tumor (nephroblastoma) is the most common renal malignancy in children, typically affecting children between 2 and 5 years of age. A minority of cases are associated with specific syndromes (e.g., WAGR, Beckwith-Wiedemann) and gene mutations (e.g., WT1). Wilms tumor is typically an incidental finding that manifests as a large abdominal mass. Other signs and symptoms may occur, such as hematuria and abdominal pain, especially in tumors that are large, ruptured, or metastasized. Treatment consists of tumor resection and chemotherapy for all stages (except for very low-risk tumors), while radiation is predominantly used in advanced disease.
Epidemiological data refers to the US, unless otherwise specified.
The exact etiology of Wilms tumor remains unknown; , but it is associated with several genetic mutations and syndromes.
Genetic predisposition 
- Gene mutations have been found in children both with and without genetic syndromes who have Wilms tumor.
- Associated with tumor supressor genes on chromosome 11 of
Associated syndromes 
- WAGR syndrome: Deletion of the 11p13 band leads to the deletion of the WT1 gene and other genes, such as PAX6. 
- Denys-Drash syndrome: point mutation in WT1 gene, which encodes a zinc finger transcription factor 
- : mutations of the WT2 gene
Palpable abdominal mass (often found incidentally)
- Unilateral and large but not crossing midline
- Smooth and firm
- Abdominal pain (∼ 40% of cases)
Other signs and symptoms
- Hematuria (∼ 25% of cases)
- Hypertension (∼ 25% of cases)
- In cases of subcapsular hemorrhage:
- Symptoms caused by metastatic spread (e.g., pulmonary symptoms)
|National Wilms Tumor Study (NWTS) system |
|Stage||Tumor location||Tumor spread||Surgery|
|I|| || |
|III|| || |
|V|| || |
- Urinalysis: hematuria may be present
- Wilms tumor consists of embryonic glomerular structures.
- May include cysts, hemorrhage, or necrosis
- Typically has a pseudocapsule
- Classic type: consists of three cell types
- Anaplastic type
|Differential diagnosis of Wilms tumor and neuroblastoma |
|Clinical findings (e.g., fever, weight loss)|| || |
|CT/MRI findings (e.g., calcifications, vascular encasement, midline crossing)|| || |
|I-123 MIBG scan|| || |
|Catecholamine metabolites in urine (VMA, HVA)|| || |
Other renal tumors
- Clear cell sarcoma
- Rhabdoid tumor
- Congenital mesoblastic nephroma
- Renal cell carcinoma
- Renal medullary carcinoma
The differential diagnoses listed here are not exhaustive.
|Treatment of Wilms tumor according to stage|
|Treatment||Stages I and II||Stages III and IV||Stage V (bilateral)|
|Surgery||Renal parenchymal-sparing resection|| || |
|Nephrectomy|| || |
|Chemotherapy||Preoperative chemotherapy|| || |
|Doxorubicin|| || |
|Dactinomycin and vincristine|| |
|Radiation|| || || |
- Good prognosis: survival rates are > 90% 
- The majority of tumor recurrences happen within two years of treatment.
- Regular screening of children with associated syndromes (e.g., abdominal ultrasound every three months until the age of 8)