Granulomatous mastitis: is it an autoimmune disease? Diagnostic and therapeutic dilemmas

Granulomatous mastitis (GM) is a rare benign inflammatory breast disease. The clinical presentation of granulomatous mastitis usually mimics malignancy or infection. The aim of this study was to review the clinical and diagnostic features of GM and discuss the medical and surgical treatment of our series of eight GM patients. Between 2008 and 2010, eight patients were diagnosed with GM and underwent surgery. Patients were evaluated clinically and radiologically. The diagnosis of GM was confirmed in all cases by core needle or excisional biopsies. Serological tests were performed for rheumatoid factor (RF), antinuclear antibody (ANA), and anti-double-stranded DNA (anti-dsDNA). The mean patient age was 37 years. Common presenting symptoms were a hard mass, pain, inflamed hyperemic skin, and sinus formation. Serological tests for RF were positive in 6 patients, and ANA and anti-dsDNA antibodies were detected in 2 patients. All patients underwent antibiotic therapy before surgery, and were treated with wide surgical excision with negative margins. Methylprednisolone (16 mg/day for 3 months) therapy was used in 3 patients (all RF and 2 ANA/anti-dsDNA positive) following a wide excisional biopsy after a postoperative recurrence mimicking skin lesions was seen. These patients responded well to steroid therapy. The diagnosis of GM should be made carefully to avoid a misdiagnosis. Steroid therapy should be considered based on the idea that this is an autoimmune disease.