Accuracy of TB-PCR using endobronchial ultrasound guided trans-bronchial needle aspiration (EBUS-TBNA) samples in mediastinal granulomatous lymphadenopathy

Abstract

IntroductionMediastinal granulomatous lymphadenopathies, such as tuberculous lymphadenitis, sarcoidosis, are frequently encountered by respiratory physicians, and their diagnosis is based on histological and microbiological tests. Endobronchial ultrasound-guided Trans bronchial needle aspiration (EBUS-TBNA) is widely used to perform mediastinal lymph node sampling. However, very limited data is available on the yield of polymerase chain reaction for Mycobacterium tuberculosis (TB-PCR) using EBUS-TBNA samples in patients with mediastinal granulomatous lymphadenopathy. Materials and methodsA retrospective study using a prospectively collected database was performed from January 1, 2018 to December 31, 2018, to evaluate the efficacy of the TB-PCR test using EBUS-TBNA samples in patients with benign mediastinal lymphadenopathy which included both granulomatous lymphadenopathy and reactive lymphadenopathy. The cohort with reactive lymphadenopathy acted as the control group of the study population. The patients with mediastinal lymphadenopathy who were awaiting EBUS-TBNA either for diagnostic evaluation of primary disease or for staging of a known malignancy were included in the study. The patients were then followed up for 1 year post procedure with clinical and radiological evaluation. ResultsOf the 310 patients with mediastinal lymphadenopathy who underwent EBUS-TBNA, 190 cases had a benign pathology with granulomatous lymphadenopathy in 120 and reactive lymphadenopathy in 70 patients. The sensitivity, specificity, the positive predictive value and the negative predictive value of TB-PCR was at 90%, 97.14%, 98.18%, and 85% respectively. The accuracy of TB-PCR is 92.63%. ConclusionTB-PCR using EBUS-TBNA samples is an effective tool for diagnosing mediastinal granulomatous lymphadenopathy. This technique can prevent further invasive interventions like mediastinoscopy in patients whose histological and microbiological tests are non-diagnostic. It should always be performed when tuberculosis is in the differential diagnosis of a patient with mediastinal lymphadenopathy.