Scanning electron microscopy and X-ray microanalysis of foreign bodies associated with Silastic implants in humans.

Polydimethylsiloxane (Silastic) capsules containing megestrol acetate have been implanted in subcutaneous tissue as a method of long-term contraception. Histological studies revealed a granulomatous foreign body reaction around these capsules with birefringent crystals in multinucleated giant cells. Although several authors had interpreted these crystals as steroids, this seemed unlikely since the tissue had been processed with organic solvents. Analysis of these crystals by polarization microscopy, scanning electron microscopy, and X-ray microanalysis demonstrated that the material was talc. The talc was probably introduced as a contaminant from gloves during the implantation. Further analysis showed that capsule fragmentation could not have produced the material since Silastic particles could not be detected.