Psoriatic arthritis is a type of inflammatory arthritis that may develop in people with psoriasis, which is a chronic autoimmune skin condition that causes fast skin cell growth and renewal. Psoriatic arthritis is different from other forms of arthritis in that it involves the skin and it affects the joints differently.
Conditions that can mimic psoriatic arthritis include:
- Axial spondyloarthritis
- Enteropathic arthritis
- Gout
- Osteoarthritis
- Plantar fasciitis
- Reactive arthritis
- Rheumatoid arthritis
Some reasons these other conditions can seem like psoriatic arthritis is that psoriatic arthritis can present in a variety of ways, with many different symptoms that are not always obvious, especially at first.
- About 15% of people who have psoriatic arthritis have arthritis symptoms before psoriasis symptoms, so psoriatic arthritis may not be suspected.
- Some patients have psoriasis very mild or minimal symptoms, such as flakes on the scalp which may seem like dandruff or an itchy patch of skin, and they don’t realize they have psoriasis when arthritis symptoms start.
- Doctors may not immediately recognize some symptoms, such as swollen joints, pain in the heels, and fatigue as psoriatic arthritis.
- Blood tests may be confusing. Many patients with psoriatic arthritis test positive for markers of inflammation, including erythrocyte sedimentation rate (ESR) and C-reactive protein. Psoriatic arthritis is considered a “seronegative” arthritis, but there are also forms of seronegative rheumatoid arthritis (RA), in which RA patients don’t have these antibodies either.
What Are Symptoms of Psoriatic Arthritis?
Symptoms of psoriatic arthritis include:
- Skin rash (psoriasis)
- Joint pain, swelling, and stiffness
- Often on one side of the body
- Pain is worse in the morning or after resting
- Can affect any joint, but is common in the large joints of lower extremities such as the knees and ankles
- Back, hip, and shoulder pain
- Pain and stiffness of the neck and lower back
- Reduced range of motion in the joints
- Fatigue
- Heel pain and foot pain
- Skin redness and warmth
- Red patches of skin with silvery scales (plaques)
- Commonly appears on the scalp, elbows, knees, and around the ears
- Scaly and itchy skin
- Thickening skin
- Sausage-like swelling of fingers and/or toes
- Abnormal skin thickness
- Nails separate from nail bed
- Pitted, crumbling nails
- Pink eye (conjunctivitis) or other eye inflammation
What Causes Psoriatic Arthritis?
The exact cause of psoriatic arthritis is unknown, but genetic, immunologic, and environmental factors are believed to play a role.
About 40% of people who have psoriatic arthritis have family members with psoriasis or psoriatic arthritis.
How Is Psoriatic Arthritis Diagnosed?
In addition to a patient history and physical examination, tests used to diagnose psoriatic arthritis or to rule out other conditions that can mimic psoriatic arthritis include:
- Lab tests
- Blood tests
- Complete blood count (CBC)
- Erythrocyte sedimentation rate (ESR)
- C-reactive protein (CRP)
- Rheumatoid factor (RF)
- Anti-cyclic citrillunated peptide (CCP)
- Blood urea nitrogen
- Creatinine
- Uric acid
- Urinalysis
- Blood tests
- Imaging tests
- X-ray
- Ultrasound
- Magnetic resonance imaging (MRI)
What Is the Treatment for Psoriatic Arthritis?
There is no cure for psoriatic arthritis and treatment is aimed at relieving symptoms and preventing further joint damage. Treatment depends on the severity of the condition and how many joints are affected.
If the psoriatic arthritis is mild, over-the-counter medications to treat pain and inflammation may be used such as:
Treatment for more severe cases may include:
- Corticosteroid injections into the joints
- Disease-modifying antirheumatic drugs (DMARDs)
- Antitumor necrosis factor (TNF) agents
- Topical treatments for psoriasis symptoms
- Retinoid and steroid creams
- Prescription vitamin d creams
- Over-the-counter or prescription salicylic acid creams, gels, and shampoos
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https://www.niams.nih.gov/Health_Info/Psoriatic_Arthritis/default.asp
https://www.uptodate.com/contents/psoriatic-arthritis-beyond-the-basics
https://creakyjoints.org/