ABSTRACT
Psoriatic arthritis (PsA) is a chronic systemic inflammatory disease that affects approximately 0.3" of the general population and up to 20"–30" of patients with skin psoriasis. PsA has an equal distribution among men and women and can occur at any age, with a peak age of onset between 30 and 50 years. Many lines of evidence, including familial aggregation, disease concordance in twins, and genome-wide association studies (GWAS), suggest a strong genetic component in PsA. PsA is a heterogeneous disease with diverse musculoskeletal manifestations, including peripheral arthritis, axial arthritis, enthesitis, and dactylitis, as well as extra-articular manifestations, including uveitis and gut inflammation. Aberrations in both innate and adaptive immunity occur in PsA, resulting in a chronic systemic inflammatory process. The disease is characterized by cellular infiltration, with substantial accumulation of T lymphocytes and macrophages among other cells in the synovial tissue along with prominent new vessel formation.
