Imaging Findings in Idiopathic Granulomatous Mastitis

OBJECTIVE: To describe magnetic resonance (MR) imaging features of patients with a histologic diagnosis of idiopathic granulomatous mastitis (IGM). METHODS: Dynamic contrast-enhanced MR imaging was performed with a 1.5-T MR unit. Postprocessing of images included subtraction and calculation of time-intensity curves of the enhancing regions at several points in all patients. RESULTS: In addition to granulomatous inflammation, biopsy slides of 5 patients demonstrated abscess formation without a specific organism (aseptic abscess). One patient had a fibrotic tissue component. Magnetic resonance imaging findings were heterogeneously enhancing areas with (n = 5) and without (n = 1) multiple ring-like enhanced abscesses and a circumscribed lesion with heterogeneous contrast enhancement (n = 1). Time-intensity curves showed a benign pattern in all but 1 patient. CONCLUSION: Idiopathic granulomatous mastitis has a number of appearances on MR imaging. Magnetic resonance imaging with measurement of time-signal intensity curves may support the findings of ultrasonography and mammography in distinguishing benign inflammatory breast disorders from malignant ones; however, biopsy still remains the only method of definite diagnosis.