Metastatic Disease to the Breast From Extramammary Malignancies: A Multimodality Pictorial Review

This pictorial review demonstrates imaging features of extramammary malignancies metastatic to the breast seen with multiple modalities, including mammography, ultrasound, computed tomography (CT), positron emission tomography, and magnetic resonance imaging. Although rare, metastases to the breast may have a distinct imaging appearance from the appearance of primary breast cancers. They are important to identify because they can mimic benign breast disease and their treatment differs from that of primary breast cancer. Metastatic disease to the breast most commonly appears as a single round or oval mass with circumscribed margins. Sonographically it is usually hypoechoic, and with CT or magnetic resonance imaging it usually enhances. In contrast with primary breast cancer, breast metastases do not demonstrate spiculated margins and rarely have associated calcifications. A variety of clinical presentations of breast metastases are reviewed, including presentation with a palpable mass, detection at screening mammography, and detection with CT or positron emission tomography.