Silicone breast implants: pathology.

Questions as to the bioreactivity of silicone breast implants (SBIs) have recently been intensely scrutinized, most notably by the media and legal system. Pathologists must be aware of the controversy and treat each SBI and associated tissue as a potential lawsuit. Grossly, silicone is a clear, viscous substance that may be observed either within or extruding from a silastic bag. By light microscopy, silicone is a nonstainable, nonpolarizable, refractile substance. Thicker sections, especially when viewed by non-Köhler illumination, phase-contrast, and darkfield microscopy will enhance visualization. Ultrastructurally, silicone is an electron-dense, amorphous substance often located within phagocytic vacuoles or extracellularly within the stroma. Correlating electron probe microanalysis allows for reliable identification. In most cases, a fibrous capsule surrounds the SBI, with the interface lining varying from a virtually acellular to a synovial-like lining composed of phagocytic and secretory cells. Silicone can often be identified within the fibrous capsule and also in distant tissues biopsied for suspected autoimmune disorders, such as synovium, skin, and lymph nodes, often without ultrastructural evidence of cytologic effects. This study has demonstrated that silicone accumulates at distant tissue sites due to preexisting inflammation acting as a stimulus. Thus, silicone is not a primary inducer of inflammatory disease processes. These findings are supported by various large epidemiologic studies.