Comparison of Cartridge-Based Nucleic Acid Amplification Test with Fine Needle Aspiration Findings in Suspected Tubercular Lymphadenitis

Lymphadenopathy is a common but non-specific presentation of tuberculosis. Fine Needle Aspiration Cytology (FNAC) and Ziehl Neelsen (ZN) stain are preferred investigations of choice in evaluating lymphadenopathy. The aspirate obtained from FNAC may be used to perform a cartridge-based nucleic acid amplification test (CBNAAT). This study aimed to assess the efficacy of CBNAAT in the diagnosis of tubercular lymphadenopathy and to compare the CBNAAT and ZN stain microscopy results with FNAC findings. The study was conducted for a year at a tertiary referral center. FNAC was performed on 86 cases suspected of tubercular lymphadenitis. CBNAAT was performed on FNA material obtained from all these cases. Results of CBNAAT and ZN microscopy were compared with FNAC findings. CBNAAT was positive in 29 cases and ZN stain was positive in 15 cases. Out of 73 cases reported as tubercular lymphadenitis on FNAC, one case of reactive lymphoid hyperplasia and suppurative lymphadenitis was positive on the CBNAAT test. The sensitivity, specificity, and positive and negative predictive values of CBNAAT were 39.72%, 84.61%, 93.54%, and 20%, respectively. CBNAAT from FNA material can be used as an adjuvant diagnostic test in suspected tubercular lymphadenitis. However, CBNAAT cannot replace FNAC in the diagnosis of extra-pulmonary tuberculosis.