psoriatic arthritis

Psoriatic arthritis is a type of arthritis that affects the skin and nails. It causes joints to become swollen and painful- focusing on the distal interphalangeal joints. Nail pitting and Ankolysing spondylitis are associated with the condition. It can become progressively worse, similar to psoriasis.

Epidemiology

Psoriatic arthritis will affect 1.5 million Americans [1]
According to NHS inform, between 20-40% of people with psoriasis will develop psoriatic arthritis [2]
Between 2013-2015, North America and Europe found that 18-42% of people with psoriasis had arthritis as a secondary illness
In Argentina, a study carried out in 2014 found that 17 out of 100 patients with psoriases has psoriatic arthritis [3]

Source: DermNetNZ.org

Psoriatic arthritis
Yellow discolouration with thickened nails

Causes
- Inherited from family members
- Can be exacerbated by:
  - Infections
  - Accidents
  - Being overweight
  - Smoking
- Result of the immune system attacking healthy tissue [4,5]

Pathophysiology [6]
- Medical students
  - Genetic risk factors contribute to the development of psoriatic arthritis and psoriasis.
  - Environmental triggers like infection or mechanical stress initiate chronic inflammation involving joints and skin, leading to IL-23 production, a central cytokine in the pathogenesis.
  - Enthesitis, inflammation at sites where ligaments, tendons, and joint capsules attach to bone, is a prominent feature of psoriatic arthritis, unlike synovitis in rheumatoid arthritis.
  - Distal interphalangeal (DIP) joints are commonly affected in psoriatic arthritis due to many entheses and little synovial tissue.
  - IL-23 stimulates resident T cells, leading to the production of IL-17, IL-22, and TNF-alpha, promoting inflammation, bone loss, and osteoproliferation.
  - CD8+ T cells play a central role, supported by the association of psoriatic arthritis with HLA Class I alleles and oligoclonal expansion of CD8+ T cells.
  - Other immune cells involved include CD4+ Th17 cells, type 3 innate lymphoid (ILC3) cells, and gamma-delta T cells, which produce proinflammatory cytokines like IL-17, IL-22, and TNF-alpha.
  - Proinflammatory cytokines recruit neutrophils, activate synoviocytes, promote angiogenesis, activate osteoclasts leading to bone destruction, and osteoblasts resulting in new bone formation.
  - Therapies like TNF inhibitors, IL-17 inhibitors, IL-12/23 inhibitors, and IL-23 inhibitors have been developed based on the understanding of the pathophysiology and are used to treat psoriatic arthritis and psoriasis.
- Patients
  - Genetic risk factors contribute to the development of psoriatic arthritis and psoriasis.
  - Environmental triggers like infection or mechanical stress initiate chronic inflammation involving joints and skin, leading to inflammatory protein production, a central cytokine in the pathogenesis.
  - Enthesitis, inflammation at sites where ligaments, tendons, and joint capsules attach to bone, is a prominent feature of psoriatic arthritis, unlike synovitis (inflammation of the synovial fluid) in rheumatoid arthritis.
  - Distal interphalangeal joints (found in the fingers) are commonly affected in psoriatic arthritis due to many entheses and little synovial tissue.
  - Inflammatory proteins stimulate resident T cells, leading to the production of other inflammatory proteins, promoting inflammation, bone loss, and osteoproliferation (new bone forming in bone-adjacent soft tissues)
  - CD8+ T cells play a central role, supported by the association of psoriatic arthritis with the expansion of cells.
  - Other immune cells produce pro-inflammatory proteins
  - Proinflammatory proteins recruit neutrophils, activate synoviocytes (cells of synovial fluid), promote angiogenesis (blood vessel formation), activate bone reducing cells leading to bone destruction, and bon building cells resulting in new bone formation.
  - Therapies like protein inhibitors including TNF inhibitors, IL-17 inhibitors and IL-23 inhibitors have been developed based on the understanding of the pathophysiology and are used to treat psoriatic arthritis and psoriasis.

Psoriasis on the legs

Pale, diffused lines on dark skin can be a sign of psoriatic arthritis

Source: Mediscan/ Alamy Stock Photo

Psoriatic arthritis
Can affect the hands presenting with redness, inflammation and sausage shaped fingers

Risk factors [7]
- History/current psoriasis diagnosis
- Inflammatory disorder of the nail unit (nail disease)
- Obesity
- Smoking
- Excessive alcohol consumption
- Environmental triggers such as trauma, stress, infection

Presentation [8]
- Joint involvement of the fingers- including enlargement (swelling) of the joints with inflammation
- Sausage shaped deformities (dactylitis)
- Nail pitting
- Inflammation of areas where the bone attaches to the tendon, known as enthesopathy (eg. Achilles tendonitis (inflammation of the Achilles tendon)
- In Ankolysing Spondylitis, psoriatic arthritis may involve the sacral and iliac joints (found in the lower back) in its impact

Psoriatic arthritis

Dark skin has pale papular (raised bumps) around the knuckles with dryness and swelling

Investigations [1]
- Clinical examination of the joints and fingers that show a sausage shape appearance
- Blood tests to rule out rheumatoid arthritis (including rheumatoid factor and anti-cyclic citrullinated peptide antibody)- if they are positive, can suspect rheumatoid arthritis
- X-ray screening can be used to determine whether treatment contributes to further damage/ progression of damage
- Nail examination to assess ridges, pitting or abnormal growth of the nail away from the nail bed.

Differential diagnosis [9]
- Rheumatoid arthritis- another form of arthritis causing inflammation
- Reactive arthritis- triggered due to infections causing arthritic symptoms
- Ankylosing spondylitis (involvement of the lower back in symptoms)

Psoriatic arthritis

Red, swollen pinky finger on a hand that has plaque psoriasis

Management [8]
- Medical students and Patients
  - The goals of treatment are to
    - Slow the disease and possibly put it into remission
    - Relieve pain and other symptoms
    - Protect your skin and joints
    - Medications
    - NSAIDs: Non-steroidal Anti inflammatory drugs may be enough to control inflammation and pain in mild Psoriatic arthritis, like aspirin, ibuprofen (Advil, Motrin) and naproxen (Naprosyn), or with a prescription from your doctor.
    - Biologics: A type of biologic called a tumor necrosis factor (TNF) inhibitor is often the first medication doctors recommend for active PsA. Theese include adalimumab, etanercept, infliximab, golimumab and certolizumab pegol.
      - If your disease is very severe or it doesn’t respond to one or more TNF inhibitors, your doctor might try a biologic that blocks interleukin-17 (IL-17) or interleukins 12 and 23 (IL 12/23)
      - Certain people who can’t take these or who don’t have adequate response may try abatacept (Orencia), a type of biologic that works differently in the body.
      - Some are more effective for skin symptoms while others work better for joints. You will not be prescribed more than one biologic at a time.
    - Disease-modifying anti-rheumatic drugs like methotrexate slow or prevent inflammation that damages joints and skin.
      - Targeted synthetic DMARDs also slow or prevent inflammation, but they target specific parts and pathways in the immune system rather than having a widespread effect, like conventional DMARDs.
    - Corticosteroids: Injecting steroids into affected joints can quickly lower inflammation and relieve pain. Steroid injections are a short-term treatment for disease flares.
      - Along with these treatments, you can use over-the-counter or prescription creams, ointments and other topical products containing steroids or nonsteroid medications, such as anthralin, vitamin A, salicylic acid or coal tar to relieve skin psoriasis.
  - Physical Therapy and Exercise
    - Staying active relieves pain and stiffness, boosts energy and mood, and improves overall health and function.
    - Avoid the pool during flares because the chlorine can irritate your skin.
  - Living With PsA
    - Stop Smoking
    - Relieve Stress
    - Eat Well
      - Ingredients in the Mediterranean diet like fatty fish (salmon, tuna, sardines), nuts and olive oil, are good for your joints and cardiovascular health.
      - Add in lean protein, colourful fruits and veggies and whole grains for well-balanced nutrition.
      - Avoid foods that contribute to inflammation, like red meats and highly processed foods that are high in trans and saturated fats and sugars.
    - Acupuncture therapy
    - Moist heat from a warm bath — or paraffin bath for hands and feet — helps relieve joint soreness. Cold from an ice pack wrapped in a towel reduces swelling. Alternate heat and cold or use whichever one feels best.
    - When you’re in pain, take a break. Rest your joints. You can go back to your normal activities once the pain has improved.
    - Lose Weight. Excess body fat fuels inflammation. Losing just 10% of your body weight if you have obesity can significantly improve your response to treatment.

Source: DermNetNZ.org

Psoriatic arthritis
Boutonniere deformity due to arthritis

Complications [10]
- Arthritis mutilans- severe, painful form of psoriatic arthritis which can lead to deformity

Myths [11]
- Having psoriasis automatically means you will have psoriatic arthritis
- Psoriatic arthritis doesn’t flare up
- There is only one type of psoriatic arthritis
- Psoriatic arthritis will always become severe as time continues
Questions to ask your doctor
- What caused by psoriatic arthritis?
- How can I check for signs of a flare up?
- What type of psoriatic arthritis do I have?
- What lifestyle changes can I make to help my symptoms?
- How long will treatment take to be effective?
- Who do I contact if I start experiencing complications?
Support
- Psoriasis and Psoriatic Arthritis Alliance
- Arthritis Foundation
- SELF.com