Fine needle aspiration cytology in diagnosing tubercular mastitis: A rare entity with differential diagnoses and learning points

Introduction Extra-pulmonary tuberculosis occurring in the breast is a rarity. The clinical presentation is multifaceted, often mimicking malignancy and pyogenic breast abscess. Fine needle aspiration cytology (FNAC) is an essential component of the triple test in evaluating breast lumps. Methods The present study is a retrospective analysis of 18 cases of tubercular mastitis (TM) over two years who underwent FNAC and were found to respond to anti-tubercular therapy on follow-up. Air-dried and alcohol-fixed smears were made and stained with May Grünwald Giemsa and hematoxylin and eosin stains. Special stains: Ziehl Neelsen (ZN), Gram, and periodic-acid Schiff (PAS) were done. In cases where pus was aspirated, material was sent for microbiological culture. For the Mycobacterium culture, Lowenstein-Jensen medium slants were employed. Results All 18 cases were female in the age range of 13-59 years (mean 29.5 years). The majority were in the age bracket of 21-30 years. Frank pus was aspirated in 9 cases. Based on FNAC characteristics, cases were divided into three groups. Group I included 10, 55.6 % cases with epithelioid cell granulomas without necrosis. Group II had 6, 33.3 % cases showing epithelioid cell granulomas and necrosis, while Group III had 2, 11.1 % cases revealing caseous necrosis without any evidence of granulomas. The correlation of these groups to acid-fast bacilli (AFB) status showed AFB positivity of 100 % in group III, followed by 66.7 % in group II and 20 % in group I. Culture was positive for Mycobacterium tuberculosis in 5 cases. Conclusion FNAC is a preliminary diagnostic modality which avoids unnecessary surgical intervention for tubercular mastitis. Demonstration of epithelioid cell granulomas in breast aspirates, even without AFB positivity in endemic regions for tuberculosis, calls for a therapeutic trial of anti-tubercular therapy.