Wilms’ tumor is a rare kidney cancer that primarily affects children. Also known as nephroblastoma, it’s the most common cancer of the kidneys in children. Wilms’ tumor most often affects children ages 3 to 4 and becomes much less common after age 5. Wilms’ tumor most often occurs in just one kidney, though it can sometimes be found in both kidneys at the same time.
- Peak incidence: 2–5 years
- Most common malignant neoplasm of the kidney in children
The exact etiology of Wilms tumor remains unknown, but it is associated with several genetic mutations and syndromes.
- Gene mutations have been found in children both with and without genetic syndromes who have Wilms tumor.
- The WT1 (Wilms tumor 1) gene is the most important Wilms tumor gene (mutated in ∼ 10–20% of cases)
- Approx. 10% of Wilms tumors occur in children with syndromes.
- Denys-Drash syndrome (point mutation in WT1 gene, which encodes a zinc finger transcription factor)
- Wilms tumor
- Pseudohermaphroditism, undescended testes in males (due to gonadal dysgenesis)
- Early-onset nephrotic syndrome
- WAGR syndrome (deletion of the 11p13 band → deletion of WT1 gene and other genes such as PAX6)
- Wilms tumor
- Genitourinary (GU) anomalies – Pseudohermaphroditism, undescended testes in males (due to gonadal dysgenesis) and early onset nephrotic syndrome
- Intellectual disability (mental Retardation)
- Beckwith-Wiedemann syndrome (mutations of WT2 gene)
- Abdominal mass (often found incidentally) which is non-tender, unilateral, not crossing midline (however, up to 10% of cases are bilateral and/or multifocal), smooth and firm.
- Other signs and symptoms include
- Abdominal pain (∼ 40% of cases)
- Hematuria (∼ 25% of cases)
- Hypertension (∼ 25% of cases)
- In cases of subcapsular hemorrhage: anemia, and possibly fever
- Symptoms caused by metastatic spread (e.g., pulmonary symptoms)
- Urinalysis: hematuria may be present
- Best initial test: USG (Hypervascular tumor, mostly uniform echogenicity with hypoechoic areas of necrosis)
- Abdominal CT/MRI: assess extent of involvement and help with surgical planning
- CT thorax/CXR: determine metastases and staging
- Biopsy is usually reserved for assessing nodules
Wilms tumor consists of embryonic glomerular structures and may include cysts, hemorrhage, or necrosis. It typically has a pseudocapsule.