Fine‐needle aspiration cytology of Bacille <scp>Calmette‐Guerin</scp> adenitis: A perplexing distinct clinical entity

Background Bacille Calmette-Guerin (BCG) adenitis is a common complication of post-BCG vaccination. Awareness of this lesser known entity in fine-needle aspiration (FNA) is important to prevent misdiagnosis. Aim This study described the clinical presentation, cytomorphological features and disease pattern in patients with BCG adenitis. Materials and methods We analyzed a series of 15 patients with BCG adenitis seen from July 2017 to July 2019. The detailed clinical and cytomorphology of these cases were studied. Results Age of presentation ranged from 3 to 12 months. Male to female ratio was 2.75:1. A total of four children were diagnosed with primary immunodeficiency. Three children had acyanotic heart disease. Most of the children had left axillary lymph node enlargement. Cytomorphology showed the presence of polymorphs (66.7%), histiocytic aggregates (80%) and reactive lymphoid population (60%). Epithelioid granulomas (26.7%) and giant cells (6.7%) were present. The necrotic background was present in all but one case. Ziehl-Neelsen stain for acid-fast bacilli was positive in all but two cases. Conclusion A high index of clinical suspicion for BCG lymphadenitis should be kept in mind for patients who are recently vaccinated. FNA cytology, combined with clinical correlation, is useful for diagnosis and management.