Comparison of Fine Needle Aspiration Cytology (FNAC) and Acid Fast Stain in the diagnosis of tubercular lymphadenitis in Rwanda (Case of University Teaching Hospital of Kigali and University Teaching Hospital of Butare)

Abstract

Tuberculosis is on the rise globally, one third of the world population is estimated to be infected with mycobacterium tuberculosis. Although, pulmonary tuberculosis is the most common condition, extra pulmonary involvement has also been documented. The most common site of extrapulmonary tuberculosis (EPT) is lymph nodes and studies conducted elsewhere have shown the use of Fine Needle Aspiration Cytology (FNAC) in the diagnosis of tuberculous lymphadenitis. However, an FNAC remains a greatly underused means of collecting specimens and has not been used systematically in Rwanda. There is little information about the accuracy of FNAC in the diagnosis of EPT. The present study was conducted on aspirates from 92 patients who presented with lymphadenopathy. The aim was to compare the accuracy of fine-needle aspiration cytology and Acid Fast staining method in the diagnosis of tubercular lymphadenitis in Rwanda. The study findings revealed that tubercular lymphadenitis was present in 39 of the 92 patients accounting for 42.4%. Cytology was more sensitive (78.6%) than Acid fast Stain (Auramine) (57.1%). On the other hand, Acid fast stain was more specific (96.6%) than cytology (69.0%). The overall accuracy for Auramine was 83.7 % whereas for cytology it was 72.1%. The level of agreement between these methods and culture was moderate and ranging from 0.42 for cytology to 0.59 for Auramine stain. Fine Needle Aspiration technique (FNA) has provided an alternative and easy procedure for collection of material for cytomorphological and bacteriologic examination of enlarged lymph nodes. Our experience suggests that FNAC should be used as preliminary screening investigation in all forms of lymphadenopathy.