A comparative study of the role of cytopathology, staining for acid-fast bacilli and genexpert MTB/RIF assay in the diagnosis of tubercular lymphadenopathy

Abstract

The diagnosis of tubercular lymphadenopathy can be made by FNAC combined with staining for AFB along with newer methods like GeneXpert assay. India carries one of the largest burdens of TB accounting for twenty-seven per cent of worldwide cases. To evaluate the role of cytopathology, AFB staining and GeneXpert assay in the rapid diagnosis of tubercular lymphadenopathy along with the usefulness of GeneXpert assay in the diagnosis of indeterminate aspirates. A total of 372 patients presenting with lymphadenopathy and clinical suspicion of a tubercular aetiology were included in the analysis.183 patients (56%) were adults (20-59 years) followed by 66 patients (20%)in the paediatric age group. 189 were females(57.3%) and 141 were males (42.7%). The cervical group of lymph nodes were most commonly involved (66%).69.1% were AFB positive in 201 smears with features favouring tubercular infection (positive cytology) which increased to 183 (91%) when GeneXpert Analysis was done, while 72 cases (55.8%) were AFB positive on cases with indeterminate cytology which showed an increment to 108 cases (83.7%) on the application of GeneXpert. FNAC combined with ZN staining and GeneXpert has a much higher diagnostic accuracy, GeneXpert further prevents underdiagnosis and enables rapid and accurate diagnosis in cases with indeterminate/inconclusive FNAC and ZN staining.