Multimodality imaging features of idiopathic granulomatous mastitis: outcome of 12 years of experience

This study was done to determine mammographic, sonographic and magnetic resonance imaging (MRI) appearances of idiopathic granulomatous mastitis, an entity clinically and radiographically resembling breast carcinoma. A total of 36 women (mean age 37 years, range 21-51 years) with histopathological diagnosis of idiopathic granulomatous mastitis were enrolled in the study. The Breast Imaging Reporting and Data System (BI-RADS) was used to categorise the levels of suspicion of malignancy on mammography. Mammography findings were classified also according to density, margin, architectural distortion and number of lesions. Lesions were classified according to number, heterogeneity and echogenic features on sonography. Dynamic MRI findings were categorised as enhancing mass lesion, nonmass lesion or both mass lesions and nonmass lesions together. Subclassification criteria for MRI included lesion shape, margin, border and internal enhancement pattern. The most common mammographic finding was either focal or diffuse asymmetric density (n=15, 44%). The most common sonographic findings were solitary or multiple circumscribed heterogeneous hypoechoic masses (n=19, 52%). Among other sonographic findings were diffuse abscess formation with fistulae and massive parenchymal heterogeneity and hypoechogenicity in 12 (33%) and five (13%) women, respectively. On MRI, enhancing mass lesions were detected in 24 patients, whereas enhancing nonmass lesions were observed in 28. Sixteen patients had both enhancing mass lesions and nonmass lesions together. Although not characteristic for this entity, asymmetric density on mammography, solitary or multiple clustered heterogeneous hypoechogenicity with a tubular configuration on sonography and round, smooth-contoured masslike lesion with rim enhancement or segmental non-mass-like lesion on MRI are the most common features of the disease.