What is the management approach for a 2-year-old boy presenting with shortness of breath (sob), hematuria, a large abdominal mass, and decreased lung perfusion?

Management of Suspected Wilms Tumor with Respiratory Compromise

This 2-year-old requires immediate hospital admission for urgent evaluation of a likely Wilms tumor with pulmonary metastases, necessitating rapid diagnostic imaging, respiratory support, and oncology consultation for chemotherapy initiation.

Immediate Stabilization and Assessment

Airway and Respiratory Management

• Admit the child immediately to hospital given the combination of respiratory compromise (shortness of breath with decreased lung perfusion) and systemic findings 1.
• Measure oxygen saturation urgently, as SpO2 below 92% indicates severe disease requiring supplemental oxygen 1.
• Monitor for signs of increased work of breathing including chest retractions, grunting, and assess the child's hydration status, activity level, and appetite 1.

Clinical Examination Priorities

• Assess for unilateral signs of decreased chest expansion, dullness to percussion, and reduced or absent breath sounds which suggest pleural effusion or metastatic disease 1.
• Document the size, location, and characteristics of the abdominal mass.
• Evaluate for signs of respiratory distress including respiratory rate, use of accessory muscles, and cyanosis 1.

Diagnostic Workup

Imaging Studies

• Obtain posteroanterior or anteroposterior chest radiographs immediately to evaluate pulmonary involvement 1.
• Ultrasound must be used to confirm the presence of any pleural fluid collection and to characterize the abdominal mass 1.
• Consider chest CT if there is suspicion of pulmonary metastases, necrotizing pneumonia, or pulmonary abscess, particularly in a child not responding to initial supportive measures 1.
• Abdominal imaging (ultrasound and/or CT) is essential to characterize the renal mass and assess for local extension.

Laboratory Investigations

• Obtain urinalysis to document hematuria and assess for infection.
• Blood cultures should be performed if there is any concern for concurrent infection 1.
• Complete blood count, renal function tests, and coagulation studies.
• Routine measurement of platelet count and clotting studies are only recommended in patients with known risk factors before any invasive procedures 1.

Differential Diagnosis Considerations

Primary Concern: Wilms Tumor with Pulmonary Metastases

The constellation of a large abdominal mass in a 2-year-old with hematuria and respiratory symptoms strongly suggests Wilms tumor (nephroblastoma) with pulmonary metastases, which occurs in approximately 10-15% of cases at presentation.

Alternative Diagnoses to Exclude

• Tuberculosis and malignancy must be excluded in the presence of pleural lymphocytosis if pleural fluid is obtained 1.
• Consider neuroblastoma, which can also present with abdominal mass but typically originates from the adrenal gland.
• Underlying rarer conditions such as immunodeficiency, inhaled foreign body, and malignancy must be considered in the initial evaluation 1.

Management Strategy

If Pleural Effusion is Present

• Ultrasound should be used to guide thoracocentesis or drain placement if significant pleural fluid is identified 1.
• Pleural fluid must be sent for microbiological analysis including Gram stain and bacterial culture, as well as differential cell count 1.
• If there is any indication the effusion is not secondary to infection, consider an initial small volume diagnostic tap for cytological analysis, avoiding general anesthesia/sedation whenever possible 1.

Respiratory Support

• Provide adequate analgesia to keep the child comfortable, particularly if respiratory distress is causing chest pain 2.
• Give antipyretics for fever management 2.
• Supplemental oxygen should be administered to maintain SpO2 >92% 1.

Oncology Consultation

• Urgent pediatric oncology consultation is essential for suspected Wilms tumor.
• Biopsy planning should be coordinated with oncology, as some protocols recommend neoadjuvant chemotherapy before surgical resection, particularly in cases with respiratory compromise from metastases.
• Avoid nephrotomy or tumor biopsy until oncology evaluation is complete, as tumor rupture can upstage the disease.

Critical Pitfalls to Avoid

• Never clamp a bubbling chest drain if one is placed 1, 2.
• If a clamped drain causes breathlessness or chest pain, immediately unclamp and seek medical advice 1, 2.
• Do not delay oncology consultation while pursuing extensive infectious workup if malignancy is suspected.
• Avoid chest physiotherapy, as it is not beneficial and should not be performed in children with pleural effusions 1, 2.

Multidisciplinary Approach

• A respiratory paediatrician should be involved early if chest tube drainage becomes necessary 1.
• Coordinate care between pediatric oncology, nephrology, surgery, and respiratory medicine.
• Early surgical consultation is essential when medical management fails or if definitive surgical intervention is planned 2.

Follow-Up Considerations

• Children should be followed up after discharge until they have recovered completely and imaging has normalized 1, 2.
• Monitor for treatment response with serial imaging and clinical assessment.
• The prognosis for Wilms tumor is generally excellent with appropriate multimodal therapy, with 5-year survival rates exceeding 90% for favorable histology tumors.