Spondyloarthropathies: Psoriatic Arthritis

Articular manifestations
Five general patterns of joint involvement have been described.(25)

•Asymmetric oligoarthritis: most joints may be involved; small joints of hands and feet are often involved, including the distal interphalangeal joints.

•Symmetric polyarthritis indistinguishable from rheumatoid arthritis: similar to that seen in rheumatoid arthritis, but with a negative rheumatoid factor. Patients with psoriasis, symmetric polyarthritis, and positive rheumatoid factor are considered to have rheumatoid arthritis and concomitant psoriasis.

•Arthritis of the distal interphalangeal joints: this form is commonly associated with nail changes. Inflammation of these joints is not seen in rheumatoid arthritis.

•Destructive arthritis (arthritis mutilans): severe deforming arthritis of small joints of the hands and feet, with osteolysis; patients may have constitutional symptoms, usually associated with severe skin disease and sacroiliitis.

•Spondylitis: may occur alone or with other forms of psoriatic arthritis and is often asymptomatic; sacroiliitis is usually asymmetric, and syndesmophytes are usually bulky, nonmarginal, and discontinuous, as in reactive arthritis.

Other musculoskeletal features of psoriatic arthritis include dactylitis, tenosynovitis, and enthesitis. Dactylitis occurs in more than 30% of patients and is characterized by a diffuse swelling of the entire digit along with arthritis of the distal interphalangeal, proximal interphalangeal, and metacarpophalangeal or metatarsophalangeal joints. Dactylitis is not seen in rheumatoid arthritis.

Extra-articular manifestations
The diagnosis of psoriatic arthritis cannot be made with certainty in the absence of psoriasis. A physical examination for hidden psoriatic lesions, particularly in the ears, the hairline, the umbilical area, the gluteal crease, and the nails is mandatory. Nail changes such as pitting, ridging, and onycholysis are often seen. Onset of arthritis occurs before skin disease in up to 20% of patients. Uveitis has been reported in 18% of patients.(7)

Laboratory and radiographic evaluation
Low titers of rheumatoid factor have been detected in 5% to 16% of patients, and antinuclear autoantibodies have been detected in 2% to 16% of the patients with psoriatic arthritis.(8,26,27) If high titers of rheumatoid factor are present in the setting of symmetric polyarthritis, the patient is considered to have rheumatoid arthritis and concomitant psoriasis.

Characteristic radiographic features include asymmetric distribution, involvement of distal interphalangeal joints, sacroiliitis, spondylitis, bone erosions and periosteal new bone formation, bony ankylosis, and resorption of the distal phalanges. The typical late change in the peripheral joint is the "pencilin- cup" erosion marked by lysis of the distal end of the proximal phalanx, with remodeling of the proximal end of the more distal phalanx.

Involvement of temporomandibular, sternoclavicular, and manubriosternal joints is common. The presence of periosteal reaction is also characteristic of enthesitis seen in this condition. Sacroiliitis tends to be asymmetric. In the spine, as in reactive arthritis, bulky, nonmarginal syndesmophytes are seen more frequently than marginal syndesmophytes.

Cleveland Clinic Journal of Medicine
Volume 71, Number 3, March 2004

This paper discusses therapies that are experimental or are not approved by the U.S. Food and Drug Administration for use under discussion.