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.