Are all Granulomatous Mastitis Cases Tuberculous?: A Study on the Role of Cytology in Evaluation of Granulomatous Mastitis

Objective: Granulomatous mastitis is a rare inflammatory condition of the breast clinically mimicking breast carcinoma and pyogenic abscess, thereby creating a diagnostic dilemma. Tuberculous mastitis is a rare clinical entity accounting for approximately 3% of all mammary lesions. All cases of granulomatous mastitis diagnosed cytologically over a period of 3 years were evaluated to ascertain the cases with tuberculous etiology. Material and Method: Fine needle aspiration cytology of the breast lump was performed and all the cytological parameters were evaluated. Wherever histopathology was available, the diagnosis was confirmed on Hematoxylin & Eosin stained sections and the Ziehl Neelsen (ZN) stain was applied. Results: A total of 10 cases of granulomatous mastitis were diagnosed on cytology during the 3-year period. On cytological smears, four cases showed presence of ill-formed granulomas and one case had scattered epithelioid histiocytes; however, the rest of the cases had well-formed granulomas. Finally, four out of ten cases were labeled as tuberculous mastitis based on the ZN stain/Tuberculosis-Polymerase chain reaction (TB-PCR) and the other six cases were granulomatous mastitis. Conclusion: Cytology plays a significant role in the diagnosis of granulomatous mastitis. This study re-emphasizes the role of the cytopathologist in the accurate and early diagnosis of these lesions so that unnecessary surgery can be avoided, and also highlights the fact that all granulomatous mastitis cases are not tuberculous.