Granulomatous Mastitis Mimicking Infection: A Case Report of Therapeutic Challenges and Evolving Management.

A 24-year-old woman presented with right breast pain and a progressively enlarging mass that had persisted for 4 months. It was initially managed as a breast abscess. However, after multiple courses of antibiotics, incision and drainage, and intralesional corticosteroid injections, her symptoms did not improve, and new areas of involvement developed. Breast ultrasound showed findings suspicious for an inflammatory lesion, and routine cultures remained negative. Breast core biopsy revealed non-caseating granulomatous inflammation, consistent with granulomatous mastitis. In the setting of a progressive course and poor response to prior therapies, systemic immunosuppressive treatment with methotrexate was initiated. At approximately 7 weeks after methotrexate initiation, she reported overall clinical improvement. In this case, the lack of response to antibiotics raised concerns for an underlying inflammatory process, emphasizing the need for early biopsy and reassessment when the clinical course is atypical. It also reflects the clinical difficulty of deciding when to shift from antibiotics to anti-inflammatory or immunosuppressive treatment.