Psoriatic arthritis (PsA) is a chronic inflammatory arthropathy associated with 
psoriasis, and included among the seronegative spondyloarthropathies. The 
presence of cutaneous psoriasis is very important for correct and early 
diagnosis of PsA, because the cutaneous lesions precede the appearance of joint 
manifestations. Thus, dermatologists are in a position to detect the condition 
at its inception. PsA is clinically subdivided into asymmetric oligoarticular 
arthritis, symmetric polyarthritis, distal interphalanges predominant, arthritis 
mutilans, and spondylitis types. PsA has several unique characteristics, such as 
enthesopathy, dactylitis and abnormal bone remodeling. Genetic, environmental, 
and immunological factors are important in its development. The triggering role 
of physical stress is seen in the "deep Koebner" phenomenon, which causes 
inflammation in the synovial membrane and in enthesis, resulting in peripheral 
arthritis. Cellular infiltrates such as activated T-cells and macrophages are 
thought to play important roles in the induction of inflammatory and destructive 
processes in joint tissues, as well as psoriatic skin. New ideas regarding the 
involvement of the IL-23/Th17 axis have emerged, and the dramatic effects of 
targeting therapies have highlighted the physiological role of key cytokines in 
psoriasis. Current views on the pathogenesis of PsA are reviewed from a 
dermatological perspective.