Myofibroblasts and free silicon around breast implants.

Fibrous tissue capsules, from around silicone breast implants, were examined by light microscopy, and by transmission and scanning electron microscopy, the latter combined with energy dispersive X-ray analysis. Contractile fibroblasts (myofibroblasts) were found in most of these fibrous capsules, and especially in those recently formed or manipulated. The element silicon was positively identified by X-ray analysis in half the tissue specimens. This material was found only around gel-filled implants. In the specimens studied, the clinical hardness of the breast was unrelated to the presence of silicon in the capsule.