Psoriasis arthritis, psoriasis arthritis 4.32/5 (22)

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Psoriatic arthritis

Inflammation of the knees is not uncommon in psoriasis arthritis. Pixabay.

Psoriatic Arthritis (Psoriasis Arthritis) ICD-10: L40,5, M07


Psoriatic arthritis is rheumatoid arthritis (Arthritis) with joint and back disease affecting 5-10% of those with psoriasis in the skin


Various types of psoriatic arthritis

Small joints are attacked

  • Fingers, especially outer joints (DIP), thumb's outer joints (IP) and middle joints (PIP). Nail psoriasis coexist with external joint affection

Asymmetrical arthritis

  • Multiple joints swell up, most large joints like knees, ankles, elbows

Symmetrical arthritis

  • Small and large joints
  • Similar to rheumatoid arthritis but not manifestation in the α-CCP


  • Rare (5%), but destroys joints in fingers and feet


  • Looks like Bekhterevs (ankylosing spondylitis), but the tissue type (blood sample) HLA-B27 occurs only in about 50% (more than 95% have HLA-B27 at ankylosing spondylitis, about 8-15% in the general population)

Illustration: “Psoriasis on back” by English Wikipedia / James Heilman, / CC BY 2.0

Classification criteria 

(CASPAR = Classification Criteria for Psoriatic Arthritis, Reference: Helliwell PS, 2005)

At least three of the following five points:

  1. Proven psoriasis (one of A, B, C)
    1. Current psoriasis
    2. Disease history of psoriasis
    3. Family history of psoriasis among first- or second-degree relatives
  2. Psoriasis nails dystrophy (including onycholysis, pitting and hyperkeratosis observed by a doctor)
  3. Negative test for RF (rheumatoid factors)
  4. Dactylitis (one of A or B)
    1. Ongoing symptoms
    2. Disease history (documented by rheumatologist)
  5. Radiologically proven juxtarticular (near joints) new bone formation (not osteophytes)


Before treatment starts, it is important to be informed about the disease, what the treatment target is and about the side effects that may occur. Treatment goal is to stop the disease completely, ie obtain remission. Unfortunately, there is no treatment that heals the disease.


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