CAPSULAR SYNOVIAL-LIKE HYPERPLASIA AROUND MAMMARY IMPLANTS SIMILAR TODETRITIC SYNOVITIS - A MORPHOLOGIC AND IMMUNOHISTOCHEMICAL STUDY OF 15 CASES

Formation of a fibrous envelope around the implant, a so-called capsul e with resultant contracture of the prosthesis, is an occasional compl ication of augmentation mammoplasty. The capsulectomy specimen contain s mature scar tissue with mononuclear cells, histiocytes, and foreign body giant cells. We studied 15 capsulectomy specimens. Seven showed a striking form of papillary villous synovial-like hyperplasia similar to detritic synovitis, a form of proliferative synovitis caused by ort hopedic prosthetic devices. There was an accompanying infiltration of the subcapsular surface by mononuclear cells, giant cells, and chronic inflammatory cells. This reaction was independent of the type of pros thetic device. In one case, foreign material consistent with polyureth ane was demonstrated by histology and electron microscopy. Among eight cases without capsular synovial-like hyperplasia (CSH), two showed de nse fibrous tissue with foamy macrophages, and the rest showed fat nec rosis, foreign body giant cell reaction, and occasional evidence of fo reign material, including silicone granulomas. We stained four of the CSH, two with silicone granulomas, and one sample with dense fibrous t issue with peanut agglutinin and antibodies against vimentin and S-100 protein. Selected cases were also stained for concanavalin A and cyto keratin. CSH stained for concanavalin A, peanut agglutinin, and viment in but was negative for cytokeratin. Our cases showed a striking simil arity in the staining pattern of CSH, detritic synovitis, and normal s ynovium. We conclude that CSH of the mammary prosthetic capsule is pat hophysiologically similar to proliferative synovitis.