Efficacy of Modified Bleach Concentration Method for Demonstration of Acid-fast Bacilli in Fine Needle Aspiration of Lymph Nodes with Clinical Suspicion of Tuberculosis

Abstract

Background: Tuberculous lymphadenitis is the most common form of extrapulmonary tuberculosis. Fine-needle aspiration
cytology of lymph node for its diagnosis is simple and safe. Conventional Ziehl-Neelsen (ZN) method for acid-fast bacilli
plays a key role in the diagnosis; however, it has variable sensitivity due to low bacterial load. We evaluated the role of
bleach concentration method before performing ZN method for the detection of mycobacterium in clinically suspected cases
of tuberculous lymphadenitis. Method: A total of 103 samples of fine-needle aspirates were collected from clinically suspected
cases of tuberculous lymphadenitis as part of routine diagnosis. All the samples were processed for cytology, conventional
ZN staining, bleach concentration followed by ZN staining. Results: As per cytomorphological diagnosis of aspirates, 50.50%
cases were categorized as reactive hyperplasia, 43.68% cases as tubercular lymphadenopathy and 5.82% cases of suppurative
lymphadenitis. The detection rates of conventional ZN method and bleach concentrated ZN method were 28.15% and 33%,
respectively. The bleach method has 100% sensitivity and specificity while conventional ZN method showed 85.29% and
100%, respectively. Conclusion: Bleach concentrated method can be done before conventional ZN staining for detection of
tubercle bacilli, as it has a higher case detection rate than that of the conventional ZN method.