Significance of Various Diagnostic Modalities in Detection of Tuberculosis in Cervical Lymphadenopathy: A Study of 200 Cases.

Background: Extrapulmonary tuberculosis (EPTB) makes for 25% of all instances of tuberculosis (TB) patients. The enigmatic clinical presentation of EPTB makes identification difficult since it simulates other chronic conditions such as neoplastic and inflammatory disorders and could culminate in treatment that is either insufficient or not required. For an affirmative and confirmed diagnosis, a substantial level of suspicion is imperative. The paucibacillary feature of EPTB makes diagnosis extremely difficult and necessitates the use of many diagnostic methods to arrive at a precise diagnosis. In December 2010, the World Health Organization recommended using GeneXpert/cartridge-based nucleic acid amplification test (CBNAAT) for the initial assessment of suspected cases of EPTB. Furthermore, fine-needle aspiration cytology (FNAC), Ziehl-Neelsen (ZN) stain, and the CBNAAT have to be utilized to exclude other possible origins of granulomatous inflammation. The goal of the current investigation is to comprehend how FNAC and ZN stains relate to CBNAAT and their diagnostic value.

Methods: The evaluation included all suspected instances of tubercular lymphadenopathy, and adequate aspirates were obtained from the site of the enlarged cervical lymph nodes. Smears were made following FNAC and stained with ZN stain as well as hematoxylin and eosin stain. Simultaneously, CBNAAT and culture evaluations were conducted on the same aspirates. This cross-sectional study took place at a tertiary care center and encompassed 200 individuals with clinical manifestations of EPTB.

Results: There were 200 cases of suspected tubercular lymphadenitis (TBLN). According to the FNAC results, TBLN was detected in 71 (47.6%) of these 200 cases, followed by necrotizing lymphadenitis in 56 (37.5%), chronic caseating granulomatous lymphadenitis in 47 (31.5%), and reactive lymphadenitis in 26 (17.4%). They were correlated with CBNAAT results, which showed that all instances of tuberculous lymphadenitis, 85.71% of cases of necrotizing lymphadenitis, 55.32% of cases of chronic caseating granulomatous lymphadenitis, and 2 (7.69%) cases of reactive lymphadenitis were CBNAAT positive.

Conclusion: CBNAAT should be utilized with FNAC and ZN staining to diagnose EPTB. The CBNAAT assay demonstrated a significant advantage in the identification of previously unidentified FNAC patients. Despite being a simple diagnostic tool, FNAC has a lower specificity and significantly lower precision than CBNAAT in correctly identifying cases of EPTB because it exhibits similar cytomorphological characteristics with lesions that are not associated with TB.