Pseudoepithelialization of Breast Implant Capsules

A review of 11 breast implant capsules revealed that 5 (45%) possessed a pseudoepithe lial lining virtually indistinguishable morphologically from true synovium. These cap sules showed a spectrum of connective tissue metaplasia that culminated in an ex tremely well-ordered double layer of columnar-appearing cells marking only for vimentin intermediate filaments and failing to stain for various cytokeratins and human factor VIII. Neither trichrome stains nor electron microscopy showed evidence of a basement membrane. The cases indicate that under appropriate conditions breast tissues can undergo mesenchymal metaplasia as well as the much more common epithelial metaplasia. Furthermore, a process morphologically identical to that previ ously described as "synovial metaplasia" in other locations also occurs in some breast capsules where, as in the dermis and in periarticular sites, its development may be dependent upon local factors such as friction and micromotion. Int J Surg Pathol 1 (3): 151-154, 1994