Comparison of CBNAAT, AFB Culture and histopathology of pleural biopsy specimens in suspected tuberculous pleural effusions undergoing pleural biopsy - Case series

Abstract

Introduction: Tuberculous pleural effusion is the second most common extrapulmonary tuberculosisl. Due to its paucibacillary nature, it is difficult to demonstrate tubercle bacilli in pleural fluid by a standard AFB staining and culture, thus leading to a large number of cases being undiagnosed or misdiagnosed2. According to RNTCP, the sensitivity of CBNAAT compared to a liquid culture is high in biopsy specimens3. However, the preferred specimen for diagnosing a pleural TB is a pleural tissue8. To date, the studies on evaluation of CBNAAT which are performed on pleural tissue are only few. Objective: To compare the yield of CBNAAT, AFB culture and histopathology of pleural tissue in suspected tuberculous pleural effusions undergoing pleural biopsy. Methodology: A case series comprising 20 patients with presumptive pleural TB underwent thoracoscopy guided pleural biopsy in the department of respiratory medicine. Specimens were sent for CBNAAT, AFB culture and for histopathological examinations. Comparative analysis of these reports were carried out. Results: Out of 20 cases, 11 were microbiologically diagnosed as tuberculous pleural effusion. Mycobacterium tuberculosis was detected by CBNAAT in 10 cases, culture showed AFB growth in 7 cases. Histopathological examination of pleural biopsy showed granulomatous inflammation in about 13 cases. Conclusion: CBNAAT is the most rapid, highly sensitive test compared to AFB culture and more confirmatory to diagnosis microbiologically confirmed tuberculosis compared to HPE