Psoriatic Arthritis

Psoriatic arthritis is a seronegative arthritis that develops in 5-8% of patients with psoriasis. In severe psoriasis, the incidence of psoriatic arthritis is as high as 39%. The onset is usually between 30 and 40 years of age.

Etiology
Several precipitating factors may play a role in the etiology of psoriatic arthritis, including:
 * 1) infections (especially streptococcal infections);
 * 2) trauma;
 * 3) stress;
 * 4) drugs such as anti-malarials and beta-blockers.

Clinical Features
The most typical pattern of joint involvement in psoriasis is an assymetric oligoarthritis or monoarthritis, which usually has a predilection for distal interphalangeal joints (DIP). This arthritis is severely damaging but rarely disabling. There is often an accompanying nail dystrophy, reflecting the inflammation in enthesis extending into the nail root. Cutaneous lesions, along with the arthritis and tenosynovitis, result in "sausage finger" appearance (dactylitis).

Another possible manifestation of psoriatic arthritis is a symmetrical polyarthritis similar to rheumatoid arthritis.

Arthritis mutilans is a mutilating form of psoriatic arthritis with severe destruction of the phalanges (osteolysis) and bone shortening, resulting in the characteristic telescopic fingers. Such a manifestations develops only in 5% of patients with psoriatic arthritis.

Treatment

 * 1) NSAIDs and/or analgesics help for pain relief, but may occasionally make the skin lesions worse;
 * 2) intra-articular corticosteroid injections for local synovitis;
 * 3) sulfasalazine or methotrexate can slow the development of joint damage;
 * 4) cyclosporin A has an effect on both the skin lesions and the arthritis;
 * 5) anti-TNF-alpha agents (for example etanercept and infliximab) are highly effective for severe psoriatic skin lesions and arthritis.

Prognosis
The prognosis of psoriatic arthritis is generally better than rheumatoid arthritis.

Related Articles

 * Psoriasis
 * Reactive Arthritis
 * Rheumatoid Arthritis