Correlation of Cytomorphology Pattern in Tuberculous Lymphadenitis with Microbiological Studies.

Background: Fine needle aspiration cytology (FNAC) is commonly used in the primary workup of suspected tuberculous lymphadenitis. Microbiological studies are essential for confirmation of diagnosis and drug resistance. However, the sensitivity of individual microbiological tests is low. We undertook this study to analyze the different cytomorphological patterns of tuberculous lymphadenitis and to compare the role of Ziehl-Neelsen (ZN) stain, Auramine-Rhodamine (AR) stain, Mycobacterium Growth Indicator Tube Culture (MGIT), and Cartridge-Based Nucleic Acid Amplification Testing (CBNAAT) in the detection of Mycobacterium tuberculosis with the final outcome.

Materials and methods: It was a prospective study of 100 clinically suspected cases of tuberculous lymphadenitis that underwent fine needle aspiration. Clinical details were noted. The material obtained was analyzed for cytology, ZN stain, AR stain, MGIT, and CBNAAT.

Result: Out of 100 cases, 94 cases were of tuberculous lymphadenitis. In this group, 34 showed granulomatous pattern, 10 showed caseation, 41 showed necrotizing granulomas, 4 showed suppurative pattern, and 4 were reactive. The remaining five cases were reactive nodes, and one case was of metastatic squamous cell carcinoma. On microbiological studies, 16 (17.02%) were positive for AR staining, 7 for ZN staining, 43 (45.74%) cases for CBNAAT, and 56 out of 94 (59.57%) were positive for MGIT. Sensitivity increased to 94.7% after combining the results of cytomorphology and all four microbiological tests.

Conclusion: The sensitivity of individual microbiological tests is low. Hence, a combination of cytomorphology with CBNAAT and MGIT is recommended for the diagnosis of tuberculous lymphadenitis, microbiological confirmation, and detection of resistance for optimum patient management.