Role of modified bleach method in staining of acid-fast bacilli in lymph node aspirates.

OBJECTIVE: To correlate acid-fast bacilli (AFB) positivity with cytomorphologic patterns of tuberculous lymphadenitis and evaluate bleach concentration method in diagnosing lymph node tuberculosis compared to Ziehl-Neelsen (ZN) method.

STUDY DESIGN: One hundred cases of tuberculous lymphadenitis diagnosed by fine needle aspiration cytology (FNAC) were analyzed and classified into 6 cytomorphologic patterns and correlated with bacillary load using routine and modified bleach methods of ZN staining. Smears were graded for AFB positivity. Sensitivity of routine ZN and modified bleach concentration was compared.

RESULTS: The classic cytomorphologic pattern of tuberculosis showing epithelioid granulomas, Langerhans giant cells and caseous necrosis was seen in 23% of cases. Routine ZN staining detected AFB in 27% of cases and the modified bleach method in 72%. In 58 cases the modified bleach method had a higher grade of AFB positivity than the routine method. The modified bleach method did not miss any AFB positivity detected on routine ZN staining.

CONCLUSION: The modified bleach method demonstrated AFB positivity in 72% of cases. AFB positivity grade was much higher than with routine ZN staining, making bacilli easily visible, with shorter screening time. The modified bleach method is inexpensive, easily performed and more sensitive and safe than routine ZN staining.