Psoriatic arthritis: evolving concepts.

Articles included in this review reflect the recent advances made in basic research and the clinical management of psoriatic arthritis in 1999. Some of these advances are destined to modify the current approach to the disease. The problems related to nosology and epidemiology, the two still controversial aspects, are discussed first. Genetic susceptibility to psoriasis and psoriatic arthritis, and the inciting role played by some bacteria, are confirmed, and attention is focused on the role of T cells, cytokines, adhesion molecules, and angiogenetic factors in the skin and synovial membrane. New classification criteria are provided and a simplified spectrum of the disease seems to emerge from clinical studies. Modern imaging techniques enable early articular changes to be discovered, support innovative pathogenetic hypotheses, and allow new therapeutic approaches.