Introduction
Tuberculous lymphadenopathy represents a challenging diagnostic scenario, particularly in regions with high TB prevalence. Its diagnosis is challenging due to the nonspecific clinical and radiological findings. Blood and skin tests for TB have variable sensitivities and specificities, so histopathologic diagnosis and molecular tests for diagnosis of TB in tissue samples may be more accurate than blood tests. Obtaining tissue samples under ultrasonography or CT guidance is sometimes very difficult and risky especially in the intra-abdominal and mediastinal regions. Endoscopic ultrasound (EUS) with EUS fine needle biopsy (EUS-FNB) is a safe technique in obtaining tissue samples for diagnosis of abdominal and mediastinal TB. EUS introduces a critical advantage of real-time imaging and precise tissue sampling. Many studies found that EUS-FNB yielded significantly higher diagnostic yield in complex TB presentations, with detection rates ranging from 78-92% across various anatomical sites. Comparative analysis with Gene X-pert MTB/RIF assay and Polymerase Chain Reaction (PCR) techniques demonstrated nuanced diagnostic capabilities. Gene X-pert provides rapid molecular detection with high specificity for rifampicin resistance while PCR offers molecular amplification of bacterial DNA.
Aims & Methods
In this prospective cross-sectional study, we explored the diagnostic efficacy of molecular techniques, specifically PCR and Gene X-pert MTB/RIF assay, in detecting Mycobacterium tuberculosis in tissue samples obtained through EUS-FNB. We also aim to evaluate the sensitivity, specificity, and rapid detection capabilities of these molecular methods compared to traditional diagnostic techniques. Patients and Methods: This study included 56 patients, 28 males and 28 females with mean age of 50 ±16 years. TB PCR or Gene X-pert was done in tissue samples including mediastinal and intra-abdominal lymphadenopathy in 75% of cases, obtained by EUS-FNB. Results: PCR or Gene X-pert for TB were true-positive in 7 cases and false negative in one case with sensitivity of 88%, specificity of 100%, positive predictive value of 100% and negative predictive value of 98%.
Results
PCR or Gene X-pert for TB were true-positive in 7 cases and false negative in one case with sensitivity of 88%, specificity of 100%, positive predictive value of 100% and negative predictive value of 98%.
Conclusion
We concluded that PCR and Gene X-pert of TB in tissues obtained by EUS-FNB are of great value in diagnosis of extrapulmonary TB.
References
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