How does the axial involvement in Psoriatic arthritis differ from that in other seronegative spondyloarthropathies?
Asymmetric sacroiliac involvement is typical of PsA and reactive arthritis.
The other major seronegative spondyloarthropathies, ankylosing spondylitis and inflammatory bowel disease, tend to be more symmetric.
Additionally, syndesmophytes are characteristically large, nonmarginal (“jug handle”-like), as opposed to the thin, marginal, symmetric syndesmophytes that occur in ankylosing spondylitis (Axial Spondyloarthritis).
Age of onset for PsA is typically older than other spondyloarthropathies and ratio of female to male patients is 1:1, whereas other spondyloarthropathies have a male predominance.