The Role of the Dermatologist in Identification and Treatment of the Early Stages of Psoriatic Arthritis

Skin Therapy Letter. 2008;13(4):4-8. 

In This Article

Making the Diagnosis

There exist several PsA classification criteria in the literature. The ClASsification criteria for Psoriatic ARthritis (CASPAR) are newly developed criteria for the diagnosis of PsA. They are simple to use, have a high specificity of 98.7%, and a sensitivity of 91.4% for the diagnosis of PsA.[18]

A patient must have inflammatory articular disease (joint, spine, or entheseal) with 3 or more of the following 5 criteria:

  1. Current OR personal history of psoriasis, OR family history of psoriasis (1st or 2nd degree relative). Psoriasis is defined as skin or scalp disease.

  2. Psoriatic nail disease including: onycholysis, pitting, hyperkeratosis on current physical exam

  3. Negative for rheumatoid factor (by any method except latex)

  4. History of or current dactylitis recorded by a rheumatologist

  5. Radiographic evidence of juxta-articular new bone formation, appearing as ill defined ossification near joint margins (but excluding osteophyte formation) on plain radiographs of the hand or foot.

Based on these criteria and established clinical features of PsA, a basic workup for a new patient in your office with psoriasis should include a history, physical examination,laboratory investigations, and review of treatment options as summarized below.

  • Current OR personal history of psoriasis, OR family history of psoriasis

  • Swelling of joints

  • Pain or tenderness in joints

  • Morning stiffness >30 minutes

  • Functional capacity in activities of daily living (changes in ability to function at home and at work and impact on quality of life), etc.

  • Nails: evidence of onycholysis, pitting, hyperkeratosis, oil-drop sign, and nail crumbling

  • Skin: see Table 1 .

  • Signs of joint inflammation such as swelling, effusion, synovial thickening, erythema, decrease in range of movement

  • Other manifestations: DIP joint involvement, enthesis, dactylitis, spondylitis and sacroiliitis, eye symptoms (i.e., iritis), etc.

  • See Table 1 for other characteristic findings for PsA.

  • Laboratory tests should include: complete blood count, erythrocyte sedimentation rate, C-reactive protein, Rh factor, and routine renal and liver function tests.

  • Plain radiographs: these can be normal in the early stages of disease. However, juxta-articular new bone formation, periarticular osteopenia, and later stages may demonstrate "pencil in cup" erosive disease in the hands or feet.


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