Role of CBNAAT (Cartridge based nucleic acid amplification test) in early diagnosis of tuberculous lymphadenopathy and drug resistant tuberculous lymphadenopathy with the help of fine needle aspiration cytology
Keywords:Tuberculous lymphadenopathy, extrapulmonary TB, CBNAAT, TB abscess, granulomatous lymphadenitis
Introduction: In the India, we had about a quarter of the world’s TB Cases with a very high incidence of MDR TB and HIV associated TB and high mortality; mostly because of lack of early diagnosis and treatment. The Extra-Pulmonary Tuberculosis (EPTB) is challenging due to the pauci-bacillary nature of the disease and limited tests. It is also necessary to rule out other causes of granulomatous inflammation on FNAC and confirmation by CBNAAT. In Dec 2010, WHO recommended CBNAAT to be used as the initial diagnostic test in suspected EPTB cases. Aim: To assess the applicability of CBNAAT in early diagnosis of TB lymphadenopathy and early identification of drug resistant TB lymphadenopathy with the help of FNAC. Material and method: A hospital based retrospective study carried out over a period of 3 years (Jan2018 to July2021) in Pathology dept, GMERS Medical College, Gandhinagar. All presumptive cases of tubercular lymphadenopathy and purulent aspirates from the lymph nodes of various sites were included in the study. Smears were made after FNA and stained with H & E stain and FNAC aspirates was collected in Falcon tube and sent tube for CBNAAT in all cases of lymphadenopathy. Results: The total number of cases with presumptive tubercular lymphadenitis was 475. Majority of the aspirates are from posterior triangle of neck lymph node accounting for 56.42% (268 cases). FNAC has detected tuberculosis in 281 (59.15%) cases. CBNAAT has detected 99 (20.84%)) cases, among them 12 cases (2.52%) which were not detected by FNA. The sensitivity of FNAC in our study was 95.9% and specificity was 100% while the sensitivity of XPERT was 29.53% and specificity was 93.4%. Conclusion: CBNAAT can be added with FNAC to get more specific results. CBNAAT is less sensitive for blood stained samples than purulent samples and hence FNA still remains as the cheapest and first line test to diagnose in cases suspected of tubercular lymphadenopathy. The present study highlights the utility of CBNAAT from FNAC material as one of the rapid and adjuvant diagnostic tool in tuberculous lymphadenopathy.
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Copyright (c) 2022 Bhaskar Thakkar, Vaidehi R Patel, Nital Panchal, Brinda Amin, Chandni Nakum
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