From the Guidelines
To diagnose TB lymphadenitis in a patient with mediastinal lymphadenopathy and a history of pleural effusion, a comprehensive diagnostic approach is needed, starting with a thorough clinical evaluation, followed by chest imaging with CT scan, and obtaining tissue samples through endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) as recommended by the Chest guideline and expert panel report 1. The clinical evaluation should include symptoms assessment, such as fever, night sweats, weight loss, and cough.
- Tuberculin skin testing or interferon-gamma release assay (IGRA) like QuantiFERON-TB Gold should be performed to support the diagnosis.
- Chest imaging with CT scan is essential to characterize the mediastinal lymphadenopathy, as suggested by the ACR appropriateness criteria for imaging of possible tuberculosis 1. The definitive diagnosis requires obtaining tissue samples through EBUS-TBNA, mediastinoscopy, or video-assisted thoracoscopic surgery (VATS), and these samples should undergo:
- Histopathological examination
- Acid-fast bacilli (AFB) staining
- Mycobacterial culture
- Nucleic acid amplification tests like GeneXpert MTB/RIF The previous pleural effusion history strongly suggests TB, especially if it was lymphocytic exudate with high adenosine deaminase levels, as indicated by the British Thoracic Society guideline for pleural disease 1. If TB lymphadenitis is confirmed, standard treatment includes a 6-month regimen with 2 months of isoniazid, rifampin, pyrazinamide, and ethambutol, followed by 4 months of isoniazid and rifampin. This approach combines clinical, radiological, and microbiological methods to establish a definitive diagnosis of TB lymphadenitis, prioritizing morbidity, mortality, and quality of life as the outcome.
From the Research
Diagnosing TB Lymphadenitis in Patients with Mediastinal Lymphadenopathy
To diagnose TB lymphadenitis in a patient with a history of mediastinal lymphadenopathy and pleural effusion 5 months ago, several diagnostic approaches can be considered:
- Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration (EBUS-TBNA): This procedure has been shown to be safe and effective in diagnosing mediastinal tuberculous lymphadenitis, with a diagnostic yield of 70.3% and an estimated sensitivity and specificity of 79.2% and 99%, respectively 2.
- Cytological and Microbiological Examinations: Combining cytopathological and microbiological examinations of EBUS-TBNA samples can improve the diagnostic accuracy of TB lymphadenitis, with a sensitivity of 87.5%, specificity of 98.5%, and accuracy of 94.4% 3.
- Mediastinoscopy: This invasive procedure can provide a tissue diagnosis in most cases of mediastinal tuberculous lymphadenitis, but it is associated with a higher risk of complications compared to EBUS-TBNA 4.
- Clinical Evaluation and Imaging: A thorough clinical evaluation, including history and physical examination, along with imaging studies such as chest X-ray and CT scan, can help identify patients with mediastinal lymphadenopathy and suggest the possibility of TB lymphadenitis 5, 6.
Diagnostic Considerations
When diagnosing TB lymphadenitis, it is essential to consider the following:
- Isolated Mediastinal Lymphadenopathy: TB lymphadenitis can present as isolated mediastinal lymphadenopathy without lung involvement, making diagnosis more challenging 5, 4.
- Asymptomatic Patients: Some patients with TB lymphadenitis may be asymptomatic, emphasizing the importance of a thorough clinical evaluation and diagnostic workup 2, 5.
- Treatment Response: Monitoring treatment response is crucial in managing TB lymphadenitis, and EBUS-TBNA can help assess treatment efficacy 2.