Psoriatic arthritis (PsA) is defined as the presence of an inflammatory arthritis, usually without any rheumatoid factor in serum (seronegative arthritis), associated with psoriasis. The annual incidence has been estimated at 1/16,000 in the adult population and prevalence has been estimated at 1/590, thus this is not a rare disease. Diagnostic criteria for PsA are still not entirely satisfactory and the most frequently used classification criteria (described by Moll and Wright) define five PsA subgroups. PsA is characterized by various clinical manifestations including symmetric polyarthritis, asymmetric oligoarthritis or polyarthritis, spinal inflammation similar to ankylosing spondylitis, peripheral enthesitis, anterior chest wall involvement or distal interphalangeal arthritis of the hands and feet, dactylitis (sausage digit or toe), arthritis mutilans and onycho-pachydermo-periostitis that are less frequent but characteristic. Enthesitis is probably the primary lesion in PsA but synovitis is also common. The pathogenesis of PsA remains to be elucidated but genetic, environmental and immunologic factors seem to play a prominent role. The treatment of PsA consists of NSAIDs (Non Steroidal Anti-Inflammatory Drugs), local steroid injections, and joint and spine rehabilitation. DMARDs (disease-modifying antirheumatic drugs) should be prescribed as early as possible for active forms of PsA. Methotrexate, leflunomide and sulfasalazine are the most frequently used DMARDs. Anti-TNF alpha therapy is indicated in peripheral or spinal forms of PsA which are active and refractory to first-line therapies.
Last update: February 2005