Comparison of conventional Ziehl–Neelsen method of acid fast bacilli with modified bleach method in tuberculous lymphadenitis

Abstract

Introduction: Tuberculosis caused by Mycobacterium tuberculosis is a chronic infectious disease and a major health problem in developing countries, with lymphadenopathy being the most common presentation. Tuberculous lymphadenitis can be diagnosed on fine needle aspiration cytology of lymph node. Conventional Ziehl–Neelsen method for acid fast bacilli plays a key role in the diagnosis and monitoring of treatment for tuberculosis, however, with low sensitivity. Present study emphasizes the role of bleach concentration method in fine needle aspiration cytology of lymph nodes over conventional direct smear microscopy. Materials and Methods: The study included 75 patients with clinically suspected tuberculous lymphadenopathy who were referred to the Department of Pathology in a tertiary care hospital, Faridabad. Data regarding age, sex, duration and site of swelling, nature of aspirate, and cytomorphological diagnosis were documented for each patient. Results: Of the total 75 cases, 15 were positive both in conventional Ziehl–Neelsen method and bleach concentration method. By bleach concentration method, additional 34 cases showed positivity that were not revealed by conventional Ziehl–Neelsen method. Thus, a total 49 cases were positive for acid fast bacilli. Conclusion: There are problems in arriving at an absolute diagnosis in certain cases of tuberculous lymphadenitis when the aspirate shows polymorphous picture with occasional epithelioid cells and absence of typical Langhans giant cell or caseous necrosis. In the present study, acid fast bacilli positivity was established in 65.33% of the cases with the bleach method. Bleach method for detection of tubercle bacilli has a high case detection rate than that of the conventional Ziehl–Neelsen method.

Keywords

• Bleach technique
• conventional staining
• tuberculosis