Psoriatic arthritis.

Recent population-based studies have examined the incidence, prevalence, and survival rates of patients with psoriatic arthritis (PsA). Although there are still no completely satisfactory diagnostic criteria for PsA, Moll and Wright's criteria--although not a true classification/diagnostic scheme--are the most used. The sensitivity of these criteria is low (61%), as are the sensitivities of the European Spondyloarthropathy Study Group and Amor classification criteria for the whole spectrum of spondyloarthropathy. In some patients, PsA can occur only with peripheral enthesitis, particularly Achilles tendinitis or dactylitis. These patients may represent a subset of PsA that is not defined by the Moll and Wright or European. Spondyloarthropathy Study Group criteria and is, therefore, poorly recognized as such. Recent studies have analyzed the expression of adhesion molecules, cytokines, and chemokines in the synovial fluid and synovial membrane of patients with PsA. The therapeutic approach to PsA must be multidisciplinary, involving dermatologists and rheumatologists. Currently the most widely used second-line drugs are methotrexate, sulfasalazine, and cyclosporine. Used in combination, these drugs will probably become a well-established therapy for PsA.