Synovial metaplasia of a periprosthetic capsule surrounding a polyurethane foam breast prosthesis.

A 43-year-old woman underwent two-stage bilateral reconstruction mammoplasty using silicone-filled, polyurethane foam-covered breast implants. The permanent implants were later removed. The periprosthetic capsule demonstrated synovial metaplasia by light and electron microscopy. Synovial metaplasia is believed to be induced by the physical and chemical characteristics of the prostheses and may have important clinical implications in reducing capsular contracture and increasing host acceptance of implantable biomaterials.