DIAGNOSIS OF TUBERCULAR LYMPHADENOPATHY BY CARTRIDGE-BASED NUCLEIC ACID AMPLIFICATION TEST(CBNAAT)AND ITS CORRELATION WITH FINE NEEDLE ASPIRATION CYTOLOGY: AN INSTITUTION-BASED STUDY

Introduction: The highest burden of tuberculosis is seen in India, accounting for 21% incidence globally and a major cause of lymphadenopathy. Fine-needle aspiration cytology with Ziehl-Neelsen staining is routinely used as the diagnostic modalityfor testing Extra Pulmonary Tuberculosis. Although a presumptive diagnosis can be made easily, but due to low sensitivity, many a times definitive diagnosis is difficult. For overcoming these limitations a rapid and reliable Cartridge Based Nucleic Acid Amplification Test method by WHO (2010) has been endorsed as an initial diagnostic tool in laboratories.

Aims and Objectives:To assess the efficacy of CBNAAT in the diagnosis of tubercular lymphadenopathy and to compare it with cytological features on FNA and ZN stain.

Materials and methods:This is a one-year study done on 111 clinically suspected cases of EPTB with lymphadenopathy in the Department of Pathology. Fine needle aspirates of the lymphnodes were subjected to CBNAAT. Cytological features and ZN stain of the aspirate were compared with CBNAAT results.

Results: Of the 111 suspected cases of EPTB, 32(28.8%) were positive on ZN staining whereas 65 (58.5%) were positive by CBNAAT. Of these 65 CBNAAT positive cases, cytology revealed epithelioid granulomas with necrosis in 37 (56.9%), granulomas without necrosis in 22 (33.8%)and scattered epithelioid cells in 6 (9.3%) cases respectively.

Conclusion: Compared to FNAC and Z-N staining, CBNAAT is an effective, sensitive and rapid diagnostic tool for diagnosis of EPTB and hence suggested to be done in all suspected cases of EPTB. CBNAAT provides an extra edge in management of those undiagnosed cases which are of global concern.