Efficacy of TB-PCR using EBUS-TBNA samples in patients with intrathoracic granulomatous lymphadenopathy

Abstract

BackgroundEndobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is widely used to perform mediastinal lymph node sampling. However, little information is available on polymerase chain reaction for Mycobacterium tuberculosis (TB-PCR) using EBUS-TBNA samples in patients with intrathoracic granulomatous lymphadenopathy (IGL).MethodsA retrospective study using a prospectively collected database was performed from January 2010 to December 2014 to evaluate the efficacy of the TB-PCR test using EBUS-TBNA samples in patients with IGL. During the study period, 87 consecutive patients with isolated intrathoracic lymphadenopathy who received EBUS-TBNA were registered and 46 patients with IGL were included.ResultsOf the 46 patients with IGL, tuberculous lymphadenitis and sarcoidosis were diagnosed in 16 and 30 patients, respectively. The sensitivity, specificity, positive predictive value, and negative predictive value of TB-PCR for tuberculous lymphadenitis were 56, 100, 100, and 81 %, respectively. The overall diagnostic accuracy of TB-PCR for tuberculous lymphadenitis was 85 %. In addition, seven (17 %) patients had non-diagnostic results from a histological examination and all of them had non-diagnostic microbiological results of an acid-fast bacilli smear and culture. Four (57 %) of the seven patients with non-diagnostic results had positive TB-PCR results, and anti-tuberculosis treatment led to clinical and radiological improvement in all of the patients.ConclusionsTB-PCR using EBUS-TBNA samples is a useful laboratory test for diagnosing IGL. Moreover, this technique can prevent further invasive evaluation in patients whose histological and microbiological tests are non-diagnostic.

EBUS-TBNA in the rapid microbiological diagnosis of drug-resistant mediastinal tuberculous lymphadenopathy

“…The low sensitivity of culture as compared to that of Xpert MTB/RIF has also been attributed to the paucibacillary nature of extrapulmonary specimens with uneven distribution of bacilli and formation of clumps [26]. Such cases (Xpert MTB/RIF positive and TB culture negative) are likely to be true positives as corroborated by the high specificity of Xpert MTB/RIF [23, 25, 27]. In the current subgroup of Xpert MTB/RIF-positive and TB culture-negative patients, 22 of 25 patients showed granulomatous inflammation and three patients showed chronic inflammatory changes on histopathology.…”

“…Because the current study setting is endemic for TB, patients were treated for TB based on Xpert MTB/RIF results, histopathological findings and clinical symptoms, despite having a negative TB culture. Similar approaches have previously been used with successful treatment outcomes [27]. The possibility of cross-contamination is least likely because the Xpert MTB/RIF assay is a closed system and is processed in accredited laboratories [23].…”

Clinical Usefulness of Fungal Culture of EBUS-TBNA Needle Rinse Fluid and Core Tissue

“… 4 The indications for EBUS-TBNA have recently been expanded beyond malignant diseases to include benign diseases, such as sarcoidosis, tuberculous lymphadenitis, and fungal infections. 5 6 7 8 In addition, several studies of EBUS-TBNA in benign diseases mainly suspected tuberculosis and sarcoidosis showed a good diagnostic yield and low complication rates. 6 9 10 …”

Thoracic sarcoidosis versus tuberculosis: Need for a multi-disciplinary approach

“…[ 7 ] This was re-iterated in another Korean study on EBUS-TBNA in granulomatous lymphadenitis, wherein of the seven patients with NS cytology and negative smear results, Xpert MTB/RIF gave the diagnosis in four cases (57%). [ 8 ] Among the microbiological tests performed on TBNA samples, Xpert MTB/RIF appears to provide the highest yield. The percentage positivity for AFB in smears of TB with non-caseating granulomas is low, varying from 1.9% to 20%.…”