What is Psoriatic Arthritis?

Prevalence among caucasians 1-3%, female=male, 10-30% have PsA and psoriasis (Skin before most, simultaneous 20% and arthritis before 15%), arthritis onset 30-50 years, no correlation between skin and joints Manifestations (peripheral assymetrical oligoarticular, polyarticular symmetrical, assymetrical with DIP involvement and dactylitis, predominant spondylitis 5%, arthritis mutilans (pencil in cup on Xray) Juxta-articular new bone formation, absence of peri-articular osteopenia, and preservation of the joint space. We have nail involvement