Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration Cytology: Navigating the Diagnostic Challenge between Tuberculosis and Sarcoidosis in Endemic Regions

Objective: Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) plays an important diagnostic role in concealed pulmonary diseases. However, diagnosing sarcoidosis and differentiating it from tuberculosis is a diagnostic quandary. We, thus, aimed to evaluate EBUS-TBNA cytology in these cases in a tubercular-endemic zone. Methods: A prospective 5-year study was done in a tertiary care center on 118 patients with tuberculosis versus sarcoidosis with mediastinal lymphadenopathy who underwent EBUS-TBNA. All samples obtained were sent for cytomorphological and microbiological evaluation. On cytology analysis, demonstration of acid-fast bacilli was considered diagnostic of tuberculosis. However, in its absence, a multidisciplinary diagnostic (MDD) approach was followed to establish a diagnosis. Results: EBUS-TBNA cytology contributed in reaching the final diagnosis in 88.1% cases. Of the 55 cases of tuberculosis, cytomorphological features were contributory in 90.9% cases. Out of 29 cases of sarcoidosis, 24 showed granulomas. Microbiological tests were contributory in the final diagnosis of tuberculosis in only 21.8% cases as compared to 90.9% by cytology analysis. In 10 cases, a definitive diagnosis could not be made on cytology analysis and were finally diagnosed on the basis of MDD. A definitive distinction between tuberculosis and sarcoidosis could not be made despite MDD in four cases. Conclusion: While a diagnosis of tuberculosis can be made independently on cytological features, MDD with contributory cytological findings is essential for the diagnosis of sarcoidosis. EBUS-TBNA cytology, thus, plays an important role in the multidisciplinary strategy of approaching thoracic lesions.