Trimethoprim-Sulfamethoxazole in the Treatment of Idiopathic Granulomatous Mastitis: A Retrospective Cohort Study.

BACKGROUND AND AIMS: Idiopathic Granulomatous Mastitis (IGM) is a rare, chronic inflammatory breast condition with uncertain etiology and challenging management. Standard treatments often involve corticosteroids or surgery, both associated with significant relapse and adverse effects. Recent interest has emerged in using antibiotics such as Trimethoprim-Sulfamethoxazole (TMP-SMX) due to potential antimicrobial and anti-inflammatory benefits, though evidence remains limited. METHODS: This retrospective cohort study evaluated the effectiveness and safety of TMP-SMX compared to conventional therapies in female patients diagnosed with histologically confirmed IGM. Patients were categorized into the TMP-SMX and control groups. Primary outcomes included treatment response and recurrence rates; secondary outcomes assessed changes in lesion size, clinical severity, and adverse events. Statistical analyzes included Chi-square, Fisher's exact test, and odds ratios (ORs) with 95% confidence intervals. RESULTS: Complete clinical remission was achieved in 70.8% of TMP-SMX (N = 24) patients versus 51.2% in the control (N = 43) group (p = 0.12). Recurrence rates were comparable between groups (37.5% in the TMP-SMX group vs. 27.9% in the control group, p = 0.51). TMP-SMX patients showed trends toward reduced lesion size and milder disease, although differences were not statistically significant. Adverse events were less frequent in the TMP-SMX group, except for transient fatigue (p = 0.04). CONCLUSION: This study provides evidence that TMP-SMX is a safe and clinically effective alternative to corticosteroid-based regimens for managing idiopathic IGM. TMP-SMX demonstrated comparable efficacy, including favorable trends in lesion regression and disease severity improvement, with notably fewer systemic adverse events.