Psoriasis arthritis, psoriasis arthritis 4.15/5 (26)

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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

  • Several joints swell, most large joints such as one knee, one ankle, one elbow

Symmetrical arthritis

  • Small and large joints swell at about the same time on the right and left side of the body (symmetrical)
  • Similar Rheumatoid arthritis (arthritis), but not a rash in the blood


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


  • Looks like Bekhterevs (ankylosing spondylitis), but the tissue type (blood test) HLA-B27 occurs only in approx. 50% (more than 95% have HLA-B27 at Bekhterevs, approx. 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 juxta-articular (near joint) new bone formation (not osteophytes)


The treatment for PsA must be person-adapted largely because the disease varies greatly from person to person. Before starting treatment, it is important to be informed about the disease, what the goal of treatment is, and about side effects that may occur. The goal of treatment is to stop the disease completely, ie achieve remission, but also to reduce pain, improve quality of life, physical and social function. Unfortunately, there is no treatment that cures the disease.

Treatment guidelines

EULAR: Gossec L, 2020 (medicines)

GRAPPA / EULAR 2017, Coates LC, 2017

Norwegian Rheumatological Association / The Norwegian Medical Association


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