Psoriasis arthritis, psoriasis arthritis 4.15/5 (26)

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


Psoriatic arthritis causes rheumatic joint inflammation (Arthritis) and back disease. Almost everyone has the skin disease Psoriasis. Psoriatic arthritis has its own characteristics, but can start small and be difficult to diagnose at an early stage. The disease is classified among spondyloarthritis together with Bekhterev's disease (ankylosing spondylitis), reactive arthritis and arthritis in chronic intestinal inflammation (ulcerative colitis and Crohn's disease). If psoriatic arthritis is suspected, a doctor can refer to a rheumatologist for further consideration.

The skin disease psoriasis is a chronic autoimmune" disease in which the skin cells are renewed faster than normal. The cells in the top skin layer are usually replaced within 30 days. In the case of psoriasis, the process only takes 4-7 days. The surplus of skin cells builds up as "plaques" that peel off. Psoriasis can be associated with rheumatic disease, especially psoriasis arthritis (psoriasis arthritis). Occurrence: Approximately 2-4% of the population has psoriasis, which corresponds to 120.000 people in Norway. Psoriasis has an increased incidence in several rheumatic diseases (spondyloarthropathies, Takayasus arthritis). Disease Cause: The triggering cause is unknown, but genetic (hereditary) factors play a certain role. Symptoms: Different types of psoriasis have different characteristics. Psoriasis vulgaris (plaque psoriasis) is most common. It typically appears with dry, scaly, thick skin on the extensor sides of elbow and knees and on the scalp, but may also occur in other areas. The abnormalities are clearly defined and are unusual in the face (except for the hairline). Pustular psoriasis occurs in palms and soles of the feet as palmo-plantar pustulose or as Generalized pustulosis on the body. Small blisters are typical. They may look like infection (pus-like), but are clean (no bacteria). About 20% have pustular psoriasis at the same time as other forms of psoriasis. Psoriasis inversa is psoriasis in skin folds and on the genitals (genital). Guttate psoriasis appears as small red-violet rashes on the body. Nail psoriasis (both finger and toenails) occur in about 50% with other forms of psoriasis. The nails get an uneven surface and become thicker. The symptoms are similar to fungal infection (mycosis) in the nails. Treatment: The GP handles most cases. Severe forms need a dermatologist's assessment. Different forms of local treatment such as ointments are prescribed by a GP. Correct use is essential for a good effect. If necessary, a specialist in skin diseases (dermatologist) can prescribe light treatment (UVB/PUVA) and various anti-inflammatory drugs such as methotrexate and Biological drugs if necessary. Treatment in warm climate may also be relevant. Other useful advice; Brush and comb your hair carefully and regularly (rough handling increases skin changes), give all treatments time to work (weeks), read the instructions for use carefully and follow them, hKeep up to date on new forms of treatment. Literature: Kim WB, 2017; Norwegian psoriasis and eczema (; (USA).


About 10-30% of people with psoriasis develop psoriatic arthritis (PsA) (Alinaghi F, 2019). The incidence (prevalence) of psoriatic arthritis in Norway is estimated at 0,1-0,2% (1-2 per 1.000 people), with no definite gender difference. The usual age of onset is 30-50 years, and the disease is most common in the age group 40-59 years (Madland TM, 2005). The disease can rarely begin in childhood (juvenile psoriatic arthritis), but is much rarer than classic childhood arthritis (JIA). Psoriatic arthritis accounts for more than 50% of all spondyloarthritis (Haglund E, 2010).


The symptoms of psoriatic arthritis can be uncharacteristic joint and back pain and without special results in blood tests it can be difficult to recognize the disease at the onset of the disease. Where the skin over the joints is heavily attacked, joint inflammation can also occur (Arthritis) be difficult to diagnose. Eventually, however, typical characteristics are seen.

Most often is Psoriasis of the skin, scalp and/or i the nails first present. Patients with widespread psoriasis (more than three locations) have an increased risk (2,24 x) of PsA (reference: Wilson FC, 2009). 

Both large joints such as knees, elbows and ankles and small joints in fingers and toes can be attacked. Stiffness and joint pain develop to also include swollen joints. Quite typical is also swelling in one or more fingers or toes, so that these are swollen along their entire length ("sausage finger" / dactylitis). Back pain develops over months and consists of stiffness, especially in the morning or having been at rest over time, but they are relieved by movement (inflammatory back pain). Some people get inflammation at the Achilles tendons, under the feet or in other tendon attachments (enthesitis). The eye can also be attacked (see "Investigations" below).


Medical history ask for signs of psoriasis in the skin and psoriasis among the closest relatives. Current symptoms (see above) are mapped. One should also inquire about symptoms from the eyes.

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

Clinical examination emphasizes systematic joint and back examination, but also scalp, nails and internal organs. Eye manifestations are rarely prominent but may include Conjunctivitis (20%), dry eyes (sicca), corneal, peripheral infiltrates, uveitis (not both eyes at the same time, HLA B27 associated) (reference: Kilic B, 2013) Please read more about eye - complications of rheumatic diseases on its own page.

Laboratory tests. There are no good tests that detect psoriatic arthritis, but the inflammatory tests CRP and lowering reaction (SR) are elevated in approx. 40%. Routine tests may include CRP, SR, hgb, leukocytes with differential counts, platelets, liver, kidney and thyroid function tests, anti-CCP and ANA. HLA-B27 is present in approx. 50% with back manifestations. Urine sting. 

Imaging. Inflammation in peripheral joints is detected by clinical examination, optionally supplemented with ultrasound or MRI. Radiographically, signs of bone and cartilage damage such as narrow joint space, depressions/erosions and new bone formation/calcifications in joints (periostitis, osteophytes) or tendon attachments (entesophytes) and ossification in the back (ankylosis) are seen. Back disease is detected with X-ray, CT or MRI examinations which are similar Ankylosing spondylitis. Compared to Bekhterev's, inflammation is seen only on one side of the pelvis (unilateral sacroiliitis) more frequently in PsA. Ultrasound Doppler can detect tendonitis in sausage fingers/dactylitis and signs of inflammation in tendon attachments (enthesopathy).

Various types of psoriatic arthritis

Small joints are attacked. Fingers, especially the outer joints (DIP) (as distinct from Rheumatoid arthritis , outer joint (IP) and middle joint (PIP) of the thumb. Nail psoriasis present at the same time as external joint affection.

Asymmetrical arthritis. Several joints swell, mostly large joints such as a knee, an ankle, an elbow.

Symmetrical arthritis. Small and large joints swell approximately at the same time on the right and left side of the body (symmetrical). Similar Rheumatoid arthritis (arthritis), but not results in a-CCP in the blood.

Mutilans. Rarely (5%), but destroys joints in fingers and feet.

Spondylitis. 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)


Psoriatic arthritis is diagnosed on the basis of a thorough assessment of medical history, clinical examination, blood tests and the exclusion of similar conditions (see below). For research, "classification criteria" are used which are not necessarily as well suited to clinical practice.

Classification criteria 

Classification criteria for psoriatic arthritis (CASPAR) require peripheral or axial arthritis or enthesitis and 3 or more points/Score from the following 5 points:

1. Occurrence of psoriasis
-Present PsoriasisPsoriasis of the skin or scalp diagnosed by a dermatologist or rheumatologist2
- Medical history of psoriasisMedical history according to patient, GP, dermatologist or rheumatologist1
- Family history of psoriasisPsoriasis in first- or second-degree relatives according to the patient's information1
2. Psoriasis in the nails (nail dystrophy)Typical nail dystrophy (onycholysis, pitting, hyperkeratosis) observed by a doctor at the current consultation1
3. Negative test for rheumatic factorsDoes not apply to the latex test, otherwise all rheumatoid factor tests, preferably ELISA or nephelometry. Results over the reference areas1
4. Dactylitis
-Current dactylitisSwelling in the entire length of the finger/toe that is observed during the medical examination1
-Medical history of dactylitisAccording to rheumatologist1
5. Radiographically proven juxta-articular new bone formationPathological ossification near the joint spaces (not osteophytes) on X-ray of hands or feet
98,7% specificity and 91,4% sensitivity, Taylor W, 2006

Similar diseases / differential diagnoses

Differential diagnosis

PsA must be distinguished from other forms of spondyloarthritisRheumatoid arthritis Osteoarthrtitisgout og Systemic lupus (SLE).


Treatment for PsA must be tailored to the individual to a large extent because the course of the disease varies greatly from person to person. Before the treatment starts, it is important to be informed about the disease, what the treatment goal is, and about side effects that may occur. The aim of treatment is to stop the disease completely, that is to 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 of symptoms with Ibux, other NSAIDs or mild pain-relieving drugs. Synovial fluid drainage and cortisone injections in large swollen joints. Methotrexate and several types Biological treatment has a disease-relieving effect on joints and skin. Apremilast (Otezla) (not approved reimbursement in Norway as of 2023). More about treatment EULAR guidelines, references: Smolen JS, 2018; EULAR: Gossec L, 2020 (medicines).

Other literature on treatment here: reference: Kang EJ, 2015)

Treatment guidelines

EULAR: Gossec L, 2020 (medicines)

GRAPPA / EULAR 2017, Coates LC, 2017

Norwegian Rheumatological Association / The Norwegian Medical Association


This page has had 1 visits today

Please rate this page