ABSTRACT
The occurrence of arthritis in patients with psoriasis has been recognized since the 19th century. The frequency of inflammatory arthritis in the general population is estimated to 3%–5%, whereas among patients with psoriasis, 7%–42% have been identified as having psoriatic arthritis (PsA). Inflammatory-type arthritis presents with pain, swelling, and stiffness in the affected joints. In addition to psoriasis and nail lesions, patients with PsA have other extra-articular manifestations that help to identify the correct diagnosis. Epidemiological studies suggest that the extent of psoriasis is an important factor in the susceptibility to PsA. The spondyloarthritis of PsA can be differentiated from that of other spondyloarthropathies, particularly ankylosing spondylitis, by the presence of the peripheral arthritis, the asymmetrical nature of the syndesmophytes, and the sacroiliac involvement. Patients who continue to demonstrate persistent inflammatory activity or who have erosive disease detected on radiographs usually deserve treatment with slow-acting antirheumatic drugs.
