Histologic features of breast capsules reflect surface configuration and composition of silicone bag implants.

The fibrous capsules that develop around silicone gel breast implants may become excessively thickened and result in painful hardened breasts. This article examines the microscopic anatomy of 80 periprosthetic breast capsules removed during a 2-year period (1990-1992), and describes the histopathologic characteristics of capsules adjacent to the more recently modified implant types. Capsules were examined by routine light microscopy, with and without polarization. Several distinctive histologic patterns were recognized, and these unique patterns could be correlated with the implant type used. All capsules were lined by a cellular membrane resembling synovium. Capsules adjacent to smooth-surfaced implants were lined by an intact histiocytic membrane of uniform thickness. In contrast, the membrane adjacent to textured implants varied in thickness, and was disrupted along its length. In addition, the inner surface of capsules adjacent to textured implants was conspicuously festooned with small (.25 to .5 mm) knob-like projections that were not seen in capsules adjacent to smooth-surfaced implants. A variety of foreign materials also were observed either within or adjacent to the capsules, and included droplets of liquid silicone, irregular solid fragments of the bag envelope, geometric crystalline fragments of polyurethane, and talc. Thus, the microanatomic features of periprosthetic breast capsules reflect the composition and surface configuration of the corresponding silicone bag type.