Figure 2. Recognition of Autoinflammation: Psoriatic Arthritis as an Example.
In early RA, joint disease localisation is to the synovium—in keeping with the concept of the synovium being the primary target organ. However, in early psoriatic arthritis, the inflammatory changes have a widespread distribution and appear to relate to patterns of joint stressing around ligaments, adjacent bone, and soft tissues, rather than a specific antigen territory. The figure shows a contrast-enhanced high-resolution magnetic resonance image of a distal interphalangeal joint optimised for showing sites of inflammation (pixel size, 100 ×100 microns). There are extensive inflammatory changes in all tissues. Asterisk, site of diffuse osteitis; arrowhead, synovial enhancement; solid arrows, joint ligaments that show florid inflammatory changes at insertions and within ligaments; open arrow, extracapsular soft-tissue enhancement.