Variability in Clinical Response to Steroids in Granulomatous Mastitis: A Report of Two Cases.

Idiopathic granulomatous mastitis (IGM) is a rare, benign, chronic inflammatory breast disease that primarily affects premenopausal women, often in the postpartum period or after breastfeeding. Its nonspecific clinical and imaging presentation, frequent overlap with infectious and neoplastic conditions, and variable therapeutic response make both diagnosis and management challenging.  This report aims to describe the clinical characteristics, diagnostic approach, and corticosteroid response in two histologically confirmed cases, highlighting differences in therapeutic outcomes and the relevance of individualized regimens.  Both patients presented with chronic inflammatory breast lesions unresponsive to antibiotics and nonsteroidal anti-inflammatory drugs (NSAIDs), requiring corticosteroid therapy for disease control. One case showed partial response with frequent relapses despite prolonged treatment, whereas the other achieved complete remission with a low-dose, tapered regimen and no recurrences.  Comparative analysis and literature review suggest that disease extent and inflammatory phenotype significantly influence responsiveness, supporting early initiation of prednisone at 0.5-1 mg/kg/day with individualized tapering, and consideration of immunosuppressants in recurrent or steroid-dependent cases. Intralesional corticosteroids may be effective in localized disease, while surgery should be reserved for refractory presentations due to higher recurrence rates. These findings reinforce the role of systemic corticosteroids as first-line therapy for IGM while emphasizing the need for tailored treatment strategies and the generation of local evidence to optimize outcomes, particularly in resource-limited settings.