Figure 3.

(a) Papillary, hyperplastic, chronically inflamed synovium is shown with abundant fibrin covering the surface and multiple fragments of bone being degraded by histiocytes and multinucleated giant cells. (b) At higher magnification, fibrin is seen on the surface of the synovium with a hyperplastic synovium consistent with chronic inflammation. (c) Fibrin and bone are detailed at 40x magnification showing multiple bone fragments which is typical of a rapidly destructive joint process. (d) Bone is seen being further broken down by multinucleated giant cells.