Radiologic features of granulomatous mastitis.

Granulomatous mastitis (GM) is a recognized, but an uncommon cause of breast mass. Awareness of this condition is important, because it can clinically as well as radiologically mimic breast carcinoma. In this study, we present the imaging features of a series of 10 cases with proved diagnosis of granulomatous mastitis with emphasis on magnetic resonance (MR) findings. All those patients who were histologically proven to have GM of the breast were analyzed. Their files were reviewed and data recorded for demographic, clinical presentation and imaging appearances. The imaging features of the lesions by mammography, ultrasound, and magnetic resonance imaging were analyzed. Of the 305 patients who were surgically treated, 10 (3%) cases proved to have GM. All the patients were females with age ranging from 27 to 53 years (average 38 years and median age 36 years). Guided core biopsy was performed in all cases for confirmation of diagnosis followed by either excision biopsy (in five cases) or lumpectomy (in five cases). The final histopathologic results were chronic granulomatous inflammation consistent with tuberculosis in four cases and GM with acute inflammation, but unknown etiology in four cases and GM due to duct ectasia in two cases. GM, a rare breast condition, should be considered in the differential diagnosis of patients with a breast mass associated with inflammatory change. Routine breast imaging with US, MG, or MRI, the condition from malignant lesions and biopsy, still remains the only method of definite diagnosis.