Is nucleic acid amplification test sufficient enough for reducing the diagnostic dilemma of cervical lymph node tuberculosis? A descriptive study in a tertiary care hospital

Abstract

Background: Pulmonary tuberculosis (TB) is common clinical presentation in India, but, nowadays, extrapulmonary TB (EPTB) is also a clinical problem. At present, no single test is available for diagnosing EPTB which is rapid, cost-effective, and confirmatory. Many studies were done to diagnose and treat the pulmonary TB, though more efforts are needed for diagnosis of EPTB. Aims and Objectives: The aim of this study is to find out any test or a series of tests that reduce the diagnostic dilemma of cervical lymph node TB. Materials and Methods: A total of 170 patients with cervical lymphadenopathy were enrolled in the pathology department between July 1, 2021, and December 31, 2021. It was a descriptive study and of cross-sectional design. The Institutional Ethics Committee approval was received (No. BSMC/IEC/101 dt. January 15, 2021). Suspected malignancy cases were excluded from the study. Fine-needle aspiration (FNA) was done for all these patients and stained with Leishman-Geimsa, Papaniculaou, and Zeihl-Neelsen (ZN) stain. After FNA, all samples were sent for cartridge based nucleic acid amplification test. Results: After FNA cytology, ZN stain was done and only 9.2% of acid–fast bacilli (AFB) positive cases were found. Granuloma was found in 27.6% of cases. After nucleic acid amplification test (NAAT) study, it was found that 36.8% patients were positive. Total number of lymph node considered to be positive for TB (NAAT positive and/or ZN stain positive and/or presence of granuloma) is 85 (52.1%). As per conventional method for diagnosis of lymph node TB (presence of granuloma and/or AFB positive in ZN stain), number of cases were 50 (30.7%). NAAT test was significantly more positive in respect of ZN staining but not significantly positive in respect of presence of granuloma. Conclusion: For diagnosis of cervical lymph node TB, all three methods (NAAT, ZN stain, and Leishman-Giemsa stain) should be used simultaneously.