What is the diagnostic and treatment approach for pediatric hilar lymphadenopathy identified on a chest X-ray (CXR)?

Diagnostic and Treatment Approach for Pediatric Hilar Lymphadenopathy on CXR

For pediatric patients with hilar lymphadenopathy identified on chest X-ray (CXR), a thin-section CT scan should be performed to better characterize the nature and distribution of the lymphadenopathy, followed by appropriate diagnostic testing based on clinical presentation to determine the specific underlying cause. 1

Initial Evaluation of Hilar Lymphadenopathy

Imaging Studies

• Chest X-ray (CXR): Initial finding of hilar lymphadenopathy requires further investigation
• Thin-section CT scan: Recommended to better characterize the lymphadenopathy 1
  • Should be performed at centers with expertise in pediatric chest CT
  • Use lowest radiation dose that provides adequate diagnostic information
  • Evaluate distribution pattern (subcarinal, paratracheal, hilar regions are most common in TB) 2, 3
  • Assess for lymph node characteristics:
    • Size (nodes >1 cm are more concerning)
    • Enhancement patterns
    • Calcification
    • Conglomeration
    • Perinodal fatty stranding
    • Effect on bronchial tree (compression)

Clinical Assessment

• Evaluate for presence of symptoms:
  • Respiratory symptoms (cough, dyspnea)
  • Systemic symptoms (fever, weight loss, night sweats)
  • Specific syndrome features (Löfgren's syndrome, Heerfordt's syndrome) 1
• Assess for risk factors:
  • TB exposure
  • Family history of sarcoidosis or other granulomatous diseases
  • Immunocompromised status
  • Travel history

Diagnostic Testing Based on Clinical Presentation

For Asymptomatic Bilateral Hilar Lymphadenopathy

• If high clinical suspicion for sarcoidosis, lymph node sampling may not be necessary 1
• Close clinical follow-up is essential if sampling is deferred

For Symptomatic or Concerning Hilar Lymphadenopathy

1. Echocardiography: Recommended to rule out structural cardiovascular disease and pulmonary hypertension 1

2. Flexible bronchoscopy with bronchoalveolar lavage (BAL):

   • To exclude infection or airway abnormalities 1
   • Send BAL fluid for:
     • Microbiologic studies (cultures, PCR for pathogens)
     • Cytology (differential cell count)
     • Special stains for acid-fast bacilli if TB is suspected 1

3. Laboratory testing:

   • Complete blood count with differential
   • Inflammatory markers (ESR, CRP)
   • Tuberculin skin test or interferon-gamma release assay if TB suspected
   • Specific testing based on clinical suspicion:
     • For suspected genetic disorders: SFTPB, SFTPC, ABCA3 mutations 1
     • For suspected sarcoidosis: ACE levels, calcium levels

4. Lymph node sampling (if diagnosis remains unclear):

   • Surgical lung biopsy via video-assisted thoracoscopy (VATS) if other investigations inconclusive 1
   • Specimens should be handled according to protocols for:
     • Histopathology and immunohistochemistry
     • Microbiologic culture
     • Special studies (immunofluorescence)
     • Electron microscopy

Common Causes of Pediatric Hilar Lymphadenopathy

Infectious Causes

• Tuberculosis: Most common cause of significant hilar lymphadenopathy in endemic areas 2, 3

  • Characteristic CT findings: subcarinal (90%), hilar (85%), and paratracheal (63%) lymphadenopathy
  • Ghost-like ring enhancement pattern
  • May cause bronchial compression (25% of cases)

• Other infections:

  • Bacterial pneumonia
  • Fungal infections
  • Atypical infections (e.g., Chlamydia pneumoniae) 4

Non-infectious Causes

• Sarcoidosis: Characterized by non-caseating granulomas 1

  • Bilateral hilar lymphadenopathy is common
  • May not require biopsy if clinical presentation is typical

• Childhood interstitial lung disease (chILD): Various forms may present with hilar lymphadenopathy 1

• Malignancy: Less common but important to exclude

  • Lymphoma
  • Leukemia
  • Metastatic disease

Treatment Approach

Treatment should be directed at the underlying cause:

1. Infectious causes:

   • Tuberculosis: Standard anti-TB regimen
   • Bacterial/atypical infections: Appropriate antimicrobial therapy

2. Sarcoidosis:

   • Observation for asymptomatic cases
   • Corticosteroids for symptomatic cases 1

3. Malignancy:

   • Referral to pediatric oncology for specific treatment protocols

4. Childhood interstitial lung disease:

   • Treatment depends on specific diagnosis
   • May include supportive care, corticosteroids, or other immunomodulatory agents

Important Considerations and Pitfalls

• Interobserver variability in detecting lymphadenopathy on CT is significant; the right hilum and subcarinal regions show the best agreement among observers 5

• Point-of-care sonography through the suprasternal notch may be useful in resource-limited settings to evaluate for mediastinal lymphadenopathy 6

• Bilateral hilar lymphadenopathy without symptoms may be observed with close follow-up rather than immediate invasive testing 1

• When evaluating pleural fluid in cases with effusion, a lymphocytic predominance should raise suspicion for TB or malignancy 1

• Avoid unnecessary radiation exposure in children by using the lowest possible dose for CT imaging and considering alternative imaging modalities when appropriate 1