GRANULOMATOUS MASTITIS WITH ERYTHEMA NODOSUM: A CASE REPORT

Aim: Granulomatous mastitis is a benign inflammatory condition of the breast, typically of idiopathic origin. This case report seeks to examine the diagnosis and management of granulomatous mastitis with erythema nodosum (GMEN), a rare manifestation, and to offer insight for clinicians encountering comparable cases. Case: A 34-year-old woman presented with right breast swelling and chest pain persisting for two months. On physical examination, two palpable masses were detected in the lower outer quadrant of the right breast, along with increased temperature and tenderness. Additionally, several erythema nodosum lesions were observed on both lower extremities. Breast ultrasound revealed heterogeneity in the fatty tissue of the outer half of the right breast, with a significant increase in the ductal diameter (6.1 millimeters at its widest point) and dense content within the lumens, raising suspicion for mastitis. On the seventh day of treatment with ciprofloxacin and teicoplanin, the mass areas in the breast fistulized to the skin, initially discharging tissue fluid, followed by ulceration. A Tru-cut breast biopsy was performed on the affected area, revealing mixed inflammatory infiltrates consisting of neutrophils, lymphocytes, histiocytes, granulomatous formations, and giant cells, leading to a diagnosis of idiopathic granulomatous mastitis. After thorough evaluation for differential diagnoses, the patient was started on methylprednisolone and methotrexate. Following six months of treatment, the patient showed clinical improvement. Three months later, due to recurrence, the patient was followed up at an external center, where treatment with azathioprine and methylprednisolone was continued. Conclusion: Idiopathic granulomatous mastitis is a diagnosis of exclusion, and thorough evaluation for other potential causes, particularly malignancy, is crucial. It is also possible to prevent unnecessary antibiotic use with suspicion of infectious mastitis by keeping it in mind in differential diagnoses. Early diagnosis is essential due to the requirement for prolonged treatment with immunosuppressive agents.