[Granulomatous mastitis: a rare cause of breast swelling]

Three women, aged 37, 39 and 29 years, presented with unilateral painful swelling of the breast. Ultrasound revealed inflammation with abscess formation. Histological biopsies contained granulomatous tissue without necrosis. Corynebacterium species were cultured in the first two patients. All 3 patients were diagnosed with granulomatous mastitis and were successfully treated with doxycycline. Granulomatous mastitis is a rare disorder that may mimic breast carcinoma. It occurs most frequently in fertile women. Diagnosis is based on histological biopsy which shows granulomas without necrosis, while other causes of granulomatous inflammation, especially tuberculosis, have been excluded. The aetiology is not fully understood. It is hypothesised that the granulomatous mastitis is caused by a type IV allergic reaction. Recently an association with Corynebacterium species was suggested. Best practice treatment methods are unclear. Most patients are treated with surgical intervention and steroids, but the rate of recurrence is high (50%). Treatment with doxycycline must be considered in patients with cultured Corynebacterium species.