Cytomorphological Patterns of Tuberculous Lymphadenitis: Experience from a Tertiary Centre

Introduction: Lymphadenitis is the most common extra pulmonary manifestation of tuberculosis (TB). Tuberculous lymphadenitis is seen in nearly 35% of extra pulmonary TB. In human immunodeficiency virus (HIV) infection, extra pulmonary TB constitutes almost 53-62% of TB. Fine needle aspiration cytology (FNAC), demonstration of acid fast bacilli (AFB) by ZiehlNeelson (ZN) stain, auramine rhodamine stain, polymerase chain reaction, culture and histopathological examination of excised node are the various diagnostic modalities for tubercular lymphadenitis. FNAC is a routinely done, economical, rapid and sensitive cytological technique for diagnosis of tuberculous lymphadenitis. Diagnosis on cytomorphology along with acid fast staining will avoid unnecessary surgical intervention. Objectives: To determine frequency of cytomorphological patterns in tuberculous lymphadenitis. To correlate Acid Fast Bacilli positivity and burden with cytomorphological patterns. Material and Methods: Study was conducted at the department of Pathology, Shimoga Institute of Medical Sciences for 2 years. FNAC was done on patients presenting with lymph node enlargement and cytology smears stained with May Grunwald Giemsa, Papanicalaou & Hematoxylin & Eosin were studied. Cytologically, all cases of tuberculous lymphadenitis were categorized into 5 patterns A to E. Correlation between patterns with ZN positivity and burden was assessed. Results: Tuberculous lymphadenitis predominantly affected individuals in the 2nd & 3rd decades of life (30%), with slight female preponderance (65.7%). Cervical region was the most common lymph node involved (61.5%). Most frequent cytomorphological pattern was epithelioid granuloma with necrosis-Pattern B (47.1%), followed by epithelioid granuloma without necrosis pattern A (18.6%). Overall AFB positivity was observed in 54.2% of cases. Statistical analysis showed significant association between cytomorphological patterns & ZN stain findings (p=0.032). Notably, cases with necrosis & neutrophilic infiltrate had a higher proportion of 3+ ZN positivity (p=0.048). Conclusion: FNAC is a simple, reliable, & well-accepted procedure for diagnosing tuberculous lymphadenitis. Combining cytomorphology with ZN staining improves diagnostic accuracy. Integrating conventional & newer diagnostic techniques enhances sensitivity for early TB diagnosis in paucibacillary specimens