What tests are recommended for further evaluation of hilar lymphadenopathy?

Evaluation of Hilar Lymphadenopathy

For patients with hilar lymphadenopathy, a contrast-enhanced CT scan of the chest should be the first diagnostic test, followed by EBUS-guided lymph node sampling if the etiology remains unclear after initial evaluation. 1, 2

Initial Imaging

• High-resolution CT scan with IV contrast is essential as the first step in evaluating hilar lymphadenopathy, as it provides better characterization of lymph nodes and helps narrow the differential diagnosis 1, 2
• CT chest with IV contrast is superior for evaluation of hilar lymph nodes compared to non-contrast CT, as absence of IV contrast limits evaluation of hilar structures 1
• Contrast-enhanced CT helps differentiate lymph nodes from vascular structures and improves assessment of mediastinal invasion 1, 3

Additional Diagnostic Tests Based on Clinical Suspicion

• PET/CT is recommended if lymphoma or malignancy is suspected, with a reported sensitivity and specificity of 90% for detecting recurrent lung cancer 1
• Pulmonary function tests (spirometry and DLCO) should be performed to assess for restrictive physiology, especially if interstitial lung disease is suspected 1, 2
• Laboratory testing should include:
  • Complete blood count with differential 1
  • Serum lactate dehydrogenase (LDH) 1
  • Angiotensin-converting enzyme (ACE) if sarcoidosis is suspected 2
  • IgG4 levels if IgG4-related disease is suspected 2
  • Tuberculosis testing (interferon-gamma release assay or tuberculin skin test) 2

Lymph Node Sampling

• EBUS-guided transbronchial needle aspiration (EBUS-TBNA) should be performed if the etiology remains unclear after initial evaluation, with a diagnostic yield of 87% and minimal complications (<0.1%) 2, 4
• Core needle biopsy is preferred over fine-needle aspiration to enable histological examination 2
• Excisional or incisional lymph node biopsy is recommended if lymphoma is suspected, as FNA alone is not acceptable for diagnosing lymphoma 1
• Mediastinoscopy should be considered if EBUS-TBNA is negative but clinical suspicion for pathology remains high, as it has a higher diagnostic yield (98%) 2

Differential Diagnosis Considerations

• Sarcoidosis is confirmed in 85% of patients with suspected stage 1 disease (bilateral hilar lymphadenopathy) 2, 5
• Alternative diagnoses to consider include:
  • Tuberculosis and fungal infections (particularly histoplasmosis) 5, 6
  • Lymphoma and other malignancies 1, 7
  • Reactive lymphadenopathy (accounts for approximately 48% of isolated mediastinal/hilar lymphadenopathy cases) 4
  • Occupational exposures (silicosis, beryllium disease) 5, 6

Follow-up Recommendations

• For patients with negative EBUS-TBNA results, consider the following factors that suggest reactive lymphadenopathy:
  • Younger age 4
  • Absence of relevant comorbidities 4
  • Smaller lymph node size (<20mm) 4
• Follow-up imaging should be performed at appropriate intervals based on the suspected diagnosis and clinical course 2
• Repeat pulmonary function tests regularly if interstitial lung disease is suspected 1, 2

Important Considerations

• The negative predictive value of EBUS-TBNA in isolated mediastinal and hilar lymphadenopathy is approximately 84%, but can be higher (93.8%) in low-risk patients 4
• Reactive lymphadenopathy accounts for a significant proportion of patients with isolated mediastinal and hilar lymphadenopathy 5, 4
• For patients with suspected sarcoidosis and classic presentation (Löfgren's syndrome), lymph node sampling may not be necessary, but close clinical follow-up is required 2