FNAC in tuberculous lymphadenitis: experience from a tertiary level referral centre

In developing countries like India, tuberculous lymphadenitis is one of the most common causes of lymphadenopathy. However, anti-tubercular treatment cannot be given only on clinical suspicion. Cytomorphology with acid fast staining proves to be a valuable tool in diagnosing these cases.

To study the utility, limitations of fine needle aspiration cytology and various cytomorphological presentations in reference to Ziehl-Neelsen staining in tuberculous lymphadenitis.

In a study period of July to October 2010, three hundred and eighteen consecutive superficial lymph nodes, clinically suspected to be tuberculous were subjected to cytological evaluation with Hematoxylin & Eosin, Giemsa and Ziehl-Neelsen stained smears. In addition, demographic profile of these patients with clinical presentation was also studied.

Incidence of tuberculous lymphadenitis was 55%. Overall AFB positivity was 71.0%. Only Necrosis without epithelioid cell granulomas was the most common cytological picture and that showed highest AFB positivity also. Three-fourth of the patients presented in second to fourth decade of life. Cervical region was the most common site of involvement with solitary lymphadenopathy as the most common presentation in contrast to matted lymph nodes as reported by others.

Fine needle aspiration cytology is a safe, cheap procedure requiring minimal instrumentation and is highly sensitive to diagnose tuberculous lymphadenitis. The sensitivity can be further increased by complementing cytomorphology with acid fast staining. In acid fast staining negative cases, yield of acid fast bacilli positivity can be increased by doing Ziehl-Neelsen staining on second smear or decolourized smear revealing necrosis or by repeat aspiration. Microbiological assessment should also be done in such cases.