Psoriatic Arthritis eMedicine

Description: Psoriatic arthritis is a chronic inflammatory arthritis that is commonly associated with psoriasis. At least 5% of patients with psoriasis develop psoriatic arthritis. The association between psoriasis and arthritis was first made in the mid 19th century, but psoriatic arthritis was not clinically distinguished from rheumatoid arthritis until the 1960s. Precisely defining psoriatic arthritis is still difficult because of a lack of specific biologic tests. Psoriatic arthritis is most commonly a seronegative oligoarthritis found in patients with psoriasis with less common but characteristic differentiating features of distal joint involvement and arthritis mutilans. Because 50% of patients with psoriatic arthritis have evidence of spondyloarthropathy, often HLA-B27 associated, psoriatic arthritis has also been classified among the seronegative spondyloarthropathies.
Karolyn A Wanat, MD, Michael J Dans, MD, PhD, Abby S Van Voorhees, MD Updated: Oct 30, 2009