Cytodiagnosis of tuberculosis using modified bleach method on lymph node aspirates

BACKGROUND: The conventional Ziehl–Neelsen (ZN) staining method for demonstration of acid-fast bacilli (AFB) by direct microscopy plays a key role in the diagnosis of tuberculosis. Its major disadvantage is low sensitivity. AIMS: The present study was undertaken to emphasize the role of bleach concentration method over conventional ZN smear for detection of AFB in fine-needle aspiration (FNA) material of clinically suspected tuberculous lymphadenitis. SETTINGS AND DESIGN: Tertiary care teaching hospital, cross-sectional design. MATERIALS AND METHODS: FNAs were done on 150 patients with clinical suspicion of tuberculosis presenting with lymphadenopathy. Smears from the aspirates were processed for routine cytology and the conventional ZN method. The remaining material in the needle hub and/or the syringe was used for the bleach method. The significance of the bleach method over the conventional ZN method and cytology was analyzed. RESULTS: Among the 150 aspirates, 57% (85/150) were indicative of tuberculosis on cytology, 37% (55/150) were positive for AFB on conventional ZN method, and the smear positivity for AFB increased to 41% (62/150) on bleach method. CONCLUSION: The bleach method is simple, safe and inexpensive. It improves the microscopic detection of AFB and can be a useful contribution to routine cytology.