Imaging Findings in Patients with Granulomatous Mastitis

BACKGROUND Granulomatous mastitis (GM) is a rare inflammatory breast disease that may mimic the clinical characteristics and radiologic imaging findings of breast carcinoma. Considering the importance of making a correct diagnosis, careful radiologic evaluations and recognition of imaging features are necessary. OBJECTIVES The aim of this study was to review the radiological findings and diagnostic value of the imaging in GM. PATIENTS AND METHODS This retrospective study involved a total of 29 patients who were diagnosed with GM between 2009 and 2013 and who underwent mammography (MG) and/or ultrasound (US) examination in addition to magnetic resonance imaging (MRI) before diagnosis. RESULTS Among 14 patients over 35 years of age who underwent MG imaging, focal asymmetric, ill-defined nodular, or diffusely increased densities were detected in nine (64.3%), two (14.3%), and one (7.1%) subjects, respectively, while there were no pathological findings in two (14.3%) patients. In the overall group of 29 patients, US showed heterogeneous hypoechoic lesions with tubular extensions in 16 (55.2%), well-demarcated heterogeneous hypoechoic lesions in eight (27.6%), parenchymal heterogeneous appearance in three (10.3%), and a heterogeneous hypoechoic lesion with irregular margins in one (3.4%), with another (3.4%) patient having normal US findings. MRI findings included lesions consistent with solitary or multiple separate or confluent abscesses with marked peripheral ring enhancement in 25 (86.2%) patients, accompanied by intensity changes suggesting edematous inflammation in the peripheral parenchyma, as well as non-mass-like heterogeneous segmental and regional contrast enhancement. Four (13.8%) patients had non-mass-like segmental and regional contrast enhancement only. A histopathological diagnosis of GM was established in all patients with biopsy. CONCLUSION GM presents with a wide range of conventional radiological findings, hampering the diagnosis. In patients with inconclusive conventional findings, MRI may assist in the differential diagnosis and assessment of the extent of disease. However, a definitive diagnosis and relevant treatment require histopathological confirmation.