Common clinical features and disease mechanisms of psoriasis and psoriatic arthritis.

Psoriasis and psoriatic arthritis are chronic inflammatory diseases that significantly affect patients' quality of life. Not only do these diseases impact patients' physical well-being, but also detrimentally affect their life socially and psychologically. There are many different patterns of skin and joint involvement. Understanding the pathogenesis of these diseases has evolved greatly in the past few decades. It is now understood that psoriasis and psoriatic arthritis are T cell mediated disorders. A number of proinflammatory cytokines have been suggested as playing a role in the disease mechanism, such as tumor necrosis factor-alpha and interferon-gamma. Other important factors proposed in the pathogenesis of these diseases include the role of genetics and environmental factors. New immunomodulating therapies, which are being developed as our understanding of the involvement of innate and adaptive immunity advances, will provide patients with safer, more effective, long-term, management options.