Angiogenesis in psoriasis and psoriatic arthritis: clues to disease pathogenesis.

Psoriasis is a common chronic dermatosis occurring in 2% of the population and associated with an inflammatory arthritis--psoriatic arthritis (PsA)--in up to 40% of cases. PsA accounts for approximately 15% of patients attending early synovitis clinics, therefore it represents the second most common diagnostic category after rheumatoid arthritis. There are a number of common pathogenic features that link the skin and the joint inflammatory processes.