Comparative Study of Conventional Ziehl–Neelsen Method and Modified Bleach Concentration Method in Detection of Tubercle Bacilli in Fine-Needle Aspiration Material of Lymph Nodes

Abstract

Introduction: Tuberculous lymphadenitis is seen in nearly 35% of extrapulmonary tuberculosis. Early and accurate detection of active cases remains an important objective for appropriate treatment and reduction in the spread of the disease. Microscopy has many advantages when it comes to speed feasibility, and if its sensitivity could be improved. Liquefaction of specimens by sodium hypochlorite (NaOCl, bleach) and concentration of bacilli through centrifugation significantly increases the sensitivity of direct microscopy. Thus, the bleach concentration method has been recently described for sputum and other extra-pulmonary specimen. Aim: The aim of study is to evaluate the role of bleach concentration method in FNAC lymph nodes over conventional Ziehl–Neelsen (ZN) direct smear microscopy. Methods and Material: The prospective, cross-sectional and observational study carried out for a period of one year from December 2017 to November 2018. The study included 50 cases suspected clinically of having TB with lymphadenopathy referred for FNAC to the division of cytopathology in department of Patholology, All the aspirates by FNAC were processed for direct microscopy using conventional ZN staining and routine cytology and compared with the findings of the bleach method. Of these 50 cases 5 cases were eliminated from the study. Results: Of total 45 cases, 14 cases were positive by conventional ZN method and 29 cases by bleach concentration method. AFB positivity by bleach concentration method was more in comparison with the routine ZN stain. Conclusion: The study could establish AFB positivity in 64.44% of cases with the bleach method. This detection rate is far better than routine ZN staining.