Psoriatic arthritis is a chronic inflammatory arthritis that affects 5-42% of persons with psoriasis. Some pts, especially those with spondylitis, will carry the HLA-B27 histocompatibility antigen. Onset of psoriasis usually precedes development of joint disease; approximately 15-20% of pts develop arthritis prior to onset of skin disease. Nail changes are seen in 90% of pts with psoriatic arthritis.
PATTERNS OF JOINT INVOLVEMENT
There are five patterns of joint involvement in psoriatic arthritis.
- Asymmetric oligoarthritis: often involves distal interphalangeal/proximal interphalangeal (DIP/PIP) joints of hands and feet, knees, wrists, ankles; “sausage digits” may be present, reflecting tendon sheath inflammation.
- Symmetric polyarthritis (40%): resembles rheumatoid arthritis except rheumatoid factor is negative, absence of rheumatoid nodules.
- Predominantly DIP joint involvement (15%): high frequency of association with psoriatic nail changes.
- “Arthritis mutilans” (3-5%): aggressive, destructive form of arthritis with severe joint deformities and bony dissolution.
- Spondylitis and/or sacroiliitis: axial involvement is present in 20-40% of pts with psoriatic arthritis; may occur in absence of peripheral arthritis.
EVALUATION
- Negative tests for rheumatoid factor.
- Hypoproliferative anemia, elevated ESR.
- Hyperuricemia may be present.
- HIV infection should be suspected in fulminant disease.
- Inflammatory synovial fluid and biopsy without specific findings.
- Radiographic features include erosion at joint margin, bony ankylosis, tuft resorption of terminal phalanges, “pencil-in-cup” deformity (bone proliferation at base of distal phalanx with tapering of proximal phalanx), axial skeleton with asymmetric sacroiliitis, asymmetric nonmarginal syndesmophytes.
DIAGNOSIS
(Table 161-1)
Treatment: Psoriatic Arthritis - Coordinated therapy is directed at the skin and joints.
- Pt education, physical and occupational therapy.
- TNF modulatory agents (etanercept, infliximab, adalimumab, golimumab, certolizumab pegol) can improve joint disease and delay radiographic progression.
- Ustekinumab (anti-IL-12/23 p40 monoclonal antibody) has efficacy for both skin and joint disease.
- Apremilast (phosphodiesterase 4 inhibitor) benefit skin and joint involvement.
- Secukinumab, an IL-17A antagonist, has been found to improve disease activity and can also be used for moderate to severe plaque psoriasis.
- NSAIDs.
- Intraarticular steroid injections—useful in some settings. Systemic glucocorticoids should rarely be used as may induce rebound flare of skin disease upon tapering.
- Efficacy of gold salts and antimalarials controversial.
- Sulfasalazine 2-3 g/d has clinical efficacy but do not halt joint erosion.
- Methotrexate 15 mg/week had no improvement in synovitis but it improved skin scores and may have symptom-modifying effects.
- Leflunomide may be of benefit for skin and joint disease.
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For a more detailed discussion, see Taurog JD, Carter JD: The Spondyloarthritides, Chap. 384, p. 2169, in HPIM-19. |