Clinical Manifestations and Diagnosis of Psoriatic Arthritis

건선 관절염의 임상상과 진단

Psoriatic arthritis (PsA) is an autoimmune arthritis related to psoriasis and one of seronegative spondyloarthropathies. PsA provokes joint pain and morning stiffness more than 30 minutes, which is relieved by exercise. PsA usually affects distal small joints and exhibits asymmetry, which is one of the typical characteristics of PsA and gives clues to make a differential diagnosis between PsA and rheumatoid arthritis. Thirty to forty patients with PsA experience arthritis in one large joint or asymmetric multiple joints. Arthritis in distal joints and arthritis mutilans often develop concurrently and patterns of PsA change along with disease progression. Spondylitis is observed in 20-30% of PsA patients. In contrast to ankylosing spondylitis, spondylitis in PsA present with mild clinical symptoms despite radiological progression, inflammation limited to one spinal tract, cervical spine dominance, non-marginal syndesmophytosis. Enthesitis is also one of the typical characteristics of PsA and it frequently affects Achilles tendon, plantar fascia and tendons inserting pelvic bones. Tenosynovitis can develop accompanied by enthesitis. Typical dactylitis (sausage digit), pitting edema and nail lesions, including nail pits, onycholysis, hyperkeratosis and splinter hemorrhage, also contribute to a differential diagnosis of PsA. Anterior uveitis, SAPHO syndrome, amyloidosis and IgA nephropathy are well-known extra-articular manifestation of PsA. In 2006, a new classification-criterion for PsA was suggested by the CASPAR study. The CASPAR criteria included 5 categories with a certain number of points; 1) skin psoriasis, 2) nail lesions, 3) dactylitis, 4) negative RF and 5) bone formation around joints. The CASPAR criteria should be applied to PsA patients having at least one of three (peripheral arthritis, spondylitis and enthesitis).