Imaging spectrum of extracapsular silicone: correlation of US, MR imaging, mammographic, and histopathologic findings.

The appearance of free silicone at mammography, ultrasonography (US), and magnetic resonance (MR) imaging is variable. The classic appearance is dense areas of opacity on mammograms, a highly echogenic pattern with or without hypoechoic masses on US images, and foci of low signal intensity on fat-suppressed T1-weighted MR images or high signal intensity on water-suppressed T2-weighted MR images. Mammography is a reliable, cost-effective, and readily available means of demonstrating silicone. The major disadvantage of US is that its accuracy depends on the capability of the operator to recognize the abnormality. Although MR imaging outperforms US or mammography in detection of implant rupture, it is not clear that MR imaging is superior in detection of free or residual silicone. The sequelae of noncontained silicone include granuloma formation, fibrosis, and migration. After extrusion from an implant, silicone migrates primarily to local sites, such as the ipsilateral chest wall and axillary nodes. Migration of silicone into the axilla can involve the brachial plexus, resulting in neuropathy. Silicone can also migrate into more distal regions, including the arm and subcutaneous tissues of the abdominal wall. Whatever the source, silicone in breast tissue interferes with the interpretation of mammographic findings.