Cytomorphological Predictors of Idiopathic vs. Tubercular Granulomatous Mastitis: Study of 25 Cases

Granulomatous mastitis (GM) is a rare, chronic inflammatory breast condition that clinically and radiologically mimics breast carcinoma. GM is most commonly reported as tubercular (TB) mastitis. This study aims to identify predictive factors differentiating idiopathic and tubercular GM based on cytomorphology.

Data were retrieved from the departmental archives between January 2019 and June 2024. Additional investigations and therapeutic responses were recorded during follow-up. Based on correlation with gold standard diagnostic tools and therapeutic responses, cases were categorised into idiopathic and tubercular GM groups using cytomorphological features and analysed for risk stratification.

A total of 25 GM cases were included in the study, with a mean age of 29 ± 5.7 years. Ziehl-Neelsen (ZN) staining was positive in three cases. A histological correlation was available for 21 cases, PCR for 5 and therapeutic response for all 25 cases. Seven cases responded to antitubercular therapy (ATT), while 18 responded to steroids. Cytological diagnosis identified TB GM in 8 cases and nonspecific GM in 17 cases. The agreement between original and revised diagnoses was excellent after correlation with gold standard methods and therapeutic outcomes. Univariate and multivariate analyses revealed that a cytological diagnosis of GM with well-formed granulomas, absence of neutrophils, presence of many lymphocytes and lack of plasma cell infiltration was significantly associated (p < 0.05) with TB GM. In univariate analysis, age under 30 years was significantly associated with TB GM (p = 0.025); however, this was not significant in multivariate analysis.

Cytomorphology is a valuable and rapid tool for differentiating between TB and idiopathic GM, helping to prevent unnecessary surgical interventions while awaiting results from ancillary diagnostic techniques.