Fig. 5.

Typical histological changes in the synovium of the RA patients treated with TNF blockers and additional peculiar histological changes: TRAP-positive osteoclasts. a Discoid fibrosis in the subsynovial area is evident. The characteristic feature of RA synovium treated with TNF blocker. b Same as a. Perivascular fibrosis in the sublining area is also clear. Hematoxylin and eosin, original magnification ×100. The giant cells are located around the debris of synovium-attacked and destructed bone and/or chondroid matrix. They must be a symbol of acceleration of clearing and healing. Hematoxylin and eosin (c), and TRAP staining (d). Original magnification ×100 (c), ×40 (d)