Granulomatous mastitis: imaging findings with histopathologic correlation

The purpose of this study is to evaluate the mammographic and ultrasonographic characteristics of granulomatous mastitis and to correlate the imaging features with the histologic findings.

15 patients with diagnosis of idiopathic granulomatous mastitis were examined with mammography and ultrasonography. The clinical, pathologic and imaging features were retrospectively reviewed and correlated in all patients.

Mammographic examination showed an asymmetric density with no distinct margins in 8 patients and an ill-defined mass in 3 patients. In 4 cases, no abnormal finding was detected on the mammography. Sonographic examination demonstrated an irregular mass with tubular connections in 5 patients, single or multiple hypoechoic tubular/nodular structures in 6, and focally or segmentally decreased parenchymal echogenity with acoustic shadowing in 4 patients. The imaging findings suggested a malignant tumor in 7 patients, while an inflammatory process or intraductal papilloma was considered in the differential diagnosis of the other patients.

Granulomatous mastitis usually presents with clinical findings mimicking a carcinoma. The most common mammographic appearance of the lesion is an asymmetrically increased density, which is not characteristic for this entity. Sonographic patterns of the disease are varied and appear to relate to the histologic features. Findings include a mass-like appearance, tubular/nodular hypoechoic structures and focal decreased parenchmal echogenicity with acoustic shadowing. With awareness of the findings granulomatous mastitis can be considered in the differential diagnosis.