ABSTRACT
Introduction: This study assessed the clinical utility of endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) for the diagnosis of suspected granulomatous mediastinal lymphadenopathy.
Materials and Methods: Retrospective chart review of all patients who underwent EBUS-TBNA for suspected granulomatous mediastinal lymphadenopathy at Singapore General Hospital between December 2008 and December 2011 inclusive. Results: Over a period of 3 years, a total of 371 patients underwent EBUS-TBNA of whom 33 (9%) had the procedure performed for evaluation of suspected granulomatous mediastinal lymphadenopathy — 18 for suspected tuberculosis (TB) and non-tuberculous mycobacterial (NTM) lymphadenitis, and 15 for suspected sarcoidosis. EBUS-TBNA was diagnostic in 9 of the 13 patients with a final diagnosis of TB/NTM. EBUS-TBNA cultures were positive in 6 of them (46%), 1 showed acid-fast bacilli (AFB) although cultures were negative, and 2 had necrotising granulomatous inflammation from EBUS-TBNA biopsies and sputum cultures grew TB. EBUS-TBNA was diagnostic in 9 of the 14 patients with a final diagnosis of sarcoidosis through histology showing non-caseating granulomatous inflammation. The sensitivities of EBUS-TBNA for diagnosis of TB/NTM, sarcoidosis and overall granulomatous mediastinal lymphadenopathy were 69%, 64%, 64%; the negative predictive values were 56%, 17%, 33%; and accuracies were 78%, 67%, 70%, respectively. Conclusion: EBUS-TBNA can be useful in the diagnosis of suspected granulomatous mediastinal lymphadenopathy with sensitivities and accuracies of >60%.The clinical utility and safety of endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) in the diagnosis and mediastinal staging of patients with non-small cell lung has been well established with diagnostic accuracies reported at 85% to 100%, and a negative predictive value of 11% to 97.4%. Of all the other conditions, sarcoidosis has been the most extensively studied, and publications have reported diagnostic sensitivities of EBUS-TBNA of 79.5% to 93%. These studies were done in patients with a high pretest probability of sarcoidosis and in countries with an incidence rate of 1 to 50 per 100,000, and prevalence rate of 3 to 200 per 100,000 population. Published data on tuberculous mediastinal lymphadenopathy are scarce — one report described the utility of EBUS-TBNA in the diagnosis of tuberculosis in 2 retroviral patients with mediastinal lymphadenopathy for evaluation, whilst 2 other studies have shown sensitivities of EBUS-TBNA for diagnosis of tuberculous mediastinal lymphadenopathy of 84.2% (19 patients) and 94% (156 patients). In geographic areas where tuberculosis (TB) is endemic, it can be clinically challenging to distinguish between TB and thoracic sarcoidosis as both may present similarly with mediastinal and hilar lymphadenopathy with or without systemic manifestations of cough, fever and weight loss. In Singapore, the incidence of TB is 35 per 100,000 and that of sarcoidosis is 0.56 per 100,000 population. It would be imperative to differentiate between these 2 conditions as therapeutic management is markedly different. As such, this study set out to evaluate the clinical utility of EBUS-TBNA for suspected granulomatous mediastinal lymphadenopathy at our institution.
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