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Psoriatic arthritis (PsA) is a chronic, destructive, seronegative arthropathy seen most commonly in patients with long-standing psoriasis.
- PsA is a seronegative spondyloarthropathy characterized by inflammatory arthritis and enthesitis.
- 5 patterns of arthritis in PsA:
- Asymmetric oligoarthritis: Involves <5 small or large joints
- Distal interphalangeal (DIP) joint predominant: Osteoarthritislike, often associated with nail psoriasis
- Symmetric polyarthritis: May be indistinguishable from rheumatoid arthritis (RA), but typically milder clinical course
- Spondyloarthritis: Asymmetric and discontinuous, unlike ankylosing spondylitis (AS)
- Arthritis mutilans: Destructive, resorptive arthritis; produces so-called 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 40–57%. Characteristic radiologic changes include joint erosions that begin marginally and move centrally (“pencil-in-cup deformity”) and periostitis.
- Rheumatoid factor (RF) and cyclic citrullinated peptide (anti-CCP) antibody are usually negative. HLA-B27 may be positive.
- Peak onset age: 30–50 years
- Predominant gender: Female = Male
- Polyarthritis is more common in women.
- Spondylitis in up to 25%, more common in males
- Psoriasis precedes arthritis in the majority by an average of 12 years. Arthritis may precede psoriasis in up to 15%, and this occurs more often in children. Arthritis and psoriasis also may present simultaneously.
- Psoriasis occurs in 2–3% of the US population; 6–42% of these individuals develop PsA (1).
Prevalence: 1–2/1,000 population (1)
- Family history of PsA
- 30–40% concordance in identical twins
- HLA-B27 in 15–50% with PsA (spondylitis pattern) vs. 90% in AS
- Other HLA associations in psoriatic arthritis: HLA-B7, HLA-B38, HLA-B39, HLA-Cw6
There are no currently available prevention strategies. It is unknown if early systemic treatment of psoriasis prevents the onset of PsA.
- 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 (2)
- Osteoclast precursor cell upregulation
Unknown. Probably multifactorial: Immunologic, genetic, environmental factors
Commonly Associated Conditions