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A chronic, destructive, seronegative arthropathy most common in patients with long-standing psoriasis
- Psoriatic arthritis (PsA) is a seronegative spondyloarthropathy characterized by inflammatory arthritis and enthesitis.
- Five patterns of arthritis in PsA:
- Asymmetric oligoarthritis: <5 joints
- Distal interphalangeal (DIP) joint predominant: osteoarthritis-like, associated with nail psoriasis
- Symmetric polyarthritis: may be indistinguishable from rheumatoid arthritis (RA)—typically milder
- Spondyloarthritis: asymmetric and discontinuous, unlike ankylosing spondylitis (AS)
- Arthritis mutilans: destructive, resorptive arthritis; produces “opera-glass” or “telescoping” digit
- Although psoriasis generally is present, it may be limited in extent.
- Course of arthritis and extent of psoriasis do not appear to correlate.
- Other extra-articular features, such as iritis, are less common.
- Damaging joint disease may occur in 40–60%. Characteristic radiologic changes include “pencil-in-cup” deformity and periostitis.
- Rheumatoid factor (RF) and cyclic citrullinated peptide antibody (anti-CCP) are usually negative. HLA-B27 may be positive.
- Peak onset age: 30 to 50 years
- Predominant gender: female = male
- Polyarthritis is more common in women.
- Spondylitis in up to 25%, more common in males
- Psoriasis precedes arthritis in most patients by an average of 12 years. Arthritis preceding psoriasis occurs in up to 15% of patients, usually children. Arthritis and psoriasis may present simultaneously.
- Psoriasis occurs in 2–3% of the U.S. population; 6–42% will develop PsA (1).
Prevalence: 1 to 2/1,000 population (1)
Etiology and Pathophysiology
- CD4+/CD8+ T cells; tumor necrosis factor α (TNF-α); interleukins 1 (IL-1), 6, 8, and 10; and matrix metalloproteases present in synovial fluid
- Osteoclast precursor cell upregulation
- Unknown. Probably multifactorial: immunologic, genetic, environmental factors
- 30–40% concordance in identical twins
- HLA-B27 in 15–50% with PsA (spondylitis pattern) versus 90% in AS
- Other HLA associations in PsA: HLA-B7, HLA-B38, HLA-B39, HLA-Cw6
- Family history of PsA
No known prevention strategies; unknown whether early treatment of psoriasis prevents onset of PsA
Commonly Associated Conditions