Tuberculous Lymphadenitis: Analysis of Cytomorphological Features with Utility of Genexpert MTB/RIF and Other Microbiological Test as an Adjunct to Cytology

Objectives: This study was undertaken to categorize various cytomorphological patterns of tuberculous lymphadenitis and with utility of Xpert MTB/RIF as an adjunct to cytology. Materials and methods: Cases based on various cytomorphological features were categorized into 3 patterns as 1. Granulomatous lymphadenitis (GL), 2. Necrotizing granulomatous lymphadenitis (NGL) 3. Necrotizing lymphadenitis (NL). The utility of microbiological test on cytosmears and histopathological examination were assessed in these categories wherever available. Results: Overall cytology had 86% sensitivity, 94% specificity, 92% positive and negative predictive value for diagnosis of tuberculosis. All these categories were correlated with microbiological test and gene Xpert wherever available. NGL had higher positive predictive value indicating that this group when subjected to microbiological methods provide definite diagnosis of tuberculosis. GL had higher specificity; hence negative microbiological test should be subjected to histopathological examination to rule out other causes of granulomatous lymphadenitis. GeneXpert when combined with cytologically suspicious smears, has high sensitivity of 85% and the agreement with culture is moderate as indicated by the kappa value of 0.4%. Conclusion: A synchronous analysis of cytomorphological features and GeneXpert and other microbiological test increases the diagnostic yield of Tuberculosis. Excisional biopsy for diagnosis of tuberculosis should be recommended only for patients in whom Fine Needle Aspiration Cytology PCR is negative or there is discrepancy with the clinical impression.