Fine-needle aspiration cytology in the diagnosis of tuberculous lesions

Fine-needle aspiration (FNA) cytology is a simple, economical, highly accurate tool in the diagnosis of tuberculous lesions. It is also ideal for sample collection for ancillary studies such as Ziehl-Neelsen (Z-N) stain for acid-fast bacilli (AFB), as well as culture, radiometric, and molecular biologic studies of Mycobacterium tuberculosis. The cytologic diagnosis of tuberculous lesions depends upon demonstration of epithelioid granuloma with or without necrotic material in the smear. In studies involving multiple sites, AFB positivity by Z-N or fluorochrome stain ranges from 23% to 45% with an average of 35.5%. The positive rate of mycobacterium culture from FNA material ranges from 20.8% to 83% with an average of 57.6%. A few limitations include sampling and interpretation error and differential diagnostic problems.