Workup for Wilms Tumor
For a child with suspected Wilms tumor, obtain abdominal imaging (ultrasound or CT/MRI) to evaluate the renal mass, chest imaging (CT or chest x-ray) to assess for pulmonary metastases, and avoid initial biopsy in most cases—proceeding directly to treatment planning based on imaging findings. 1
Initial Imaging Evaluation
The diagnostic workup centers on imaging rather than tissue diagnosis:
Abdominal Assessment
- Abdominal ultrasound is the primary screening modality, particularly useful for initial detection and surveillance 1
- CT or MRI of the abdomen provides detailed anatomic information for surgical planning and staging 1
- Imaging should evaluate tumor size, laterality (unilateral vs bilateral), vascular involvement, and lymph node status
Chest Evaluation
- Chest CT or chest x-ray is mandatory to detect pulmonary metastases 1
- This is critical for staging as lung metastases significantly alter treatment approach
Critical Biopsy Considerations
Initial biopsy is NOT recommended for most children with suspected Wilms tumor 1. This is a common pitfall—the imaging appearance is typically sufficient for diagnosis and treatment planning.
Exceptions Where Biopsy Should Be Considered:
- Children >10 years of age with bilateral renal tumors or unilateral tumor with predisposing condition 1
- Concern for pathology other than Wilms tumor based on imaging characteristics 1
The rationale: biopsy risks tumor spillage and upstaging, and most cases can be managed based on imaging alone.
Genetic and Syndromic Evaluation
Assess for predisposing conditions that occur in 10-33% of Wilms tumor cases 1:
- Denys-Drash syndrome
- WAGR syndrome (Wilms tumor, Aniridia, Genitourinary anomalies, Range of developmental delays)
- Beckwith-Wiedemann syndrome
- Frasier syndrome
- Perlman syndrome
- Contralateral nephrogenic rests in children <12 months
Physical examination should specifically look for:
- Aniridia (absence of iris)
- Hemihypertrophy
- Genitourinary anomalies
- Macroglossia or other overgrowth features
Laboratory Studies
While not explicitly detailed in the guidelines, standard workup includes:
- Complete blood count
- Renal function tests (creatinine, BUN)
- Liver function tests
- Urinalysis
Staging Workup Summary
The imaging workup directly informs staging and treatment stratification:
- Local staging: Abdominal imaging determines resectability, lymph node involvement, and local extent
- Distant staging: Chest imaging identifies pulmonary metastases (Stage IV disease)
- Bilateral disease: Requires different treatment approach with neoadjuvant chemotherapy before surgery 1
Key Clinical Pitfalls to Avoid
- Do not routinely biopsy unilateral renal masses in young children with typical imaging features—this can cause tumor spillage and worsen staging
- Do not delay chest imaging—pulmonary metastases are the most common site of distant spread and fundamentally change treatment
- Do not miss bilateral disease—this requires neoadjuvant chemotherapy rather than upfront nephrectomy
- Screen for predisposing syndromes—these affect surveillance protocols and may indicate bilateral risk
Multidisciplinary Planning
Once imaging is complete, management should involve pediatric oncology, pediatric surgery, and radiation oncology to determine whether the tumor is:
- Resectable (proceed to nephrectomy followed by adjuvant therapy)
- Unresectable (neoadjuvant chemotherapy first) 1
- Bilateral (neoadjuvant chemotherapy with nephron-sparing approach) 1
The workup is streamlined and imaging-based, avoiding unnecessary invasive procedures while rapidly establishing stage and treatment pathway.