Psoriatic arthritis is a form of arthritis associated with psoriasis, a chronic skin and nail disease characterized by red, scaly rashes and thick, pitted fingernails. The disease is similar to rheumatoid arthritis in symptoms, characterized by joint inflammation. However, psoriatic arthritis tends to affect fewer joints than rheumatoid arthritis and does not produce the typical rheumatoid arthritis antibodies. The arthritis associated with psoriatic arthritis comes in five forms, including the following:
- arthritis that affects the small joints in the fingers and/or toes
- asymmetrical arthritis of the joints in the extremities
- symmetrical polyarthritis, a type of arthritis similar to rheumatoid arthritis
- arthritis mutilans, a rare type of arthritis that destroys and deforms joints
- psoriatic spondylitis, arthritis of the sacroiliac sac (in the lower back) and the spine
Psoriatic arthritis is one of four disorders which are classified as spondyloarthropathies. The other disorders are juvenile ankylosing spondylitis, inflammatory bowel disease, and Reiter's syndrome. These disorders have similar features such as:
- inflammation of the spine and sacroiliac joints
- family history of the disease
- similar non-arthritis symptoms
- absence of rheumatoid factor (RF) in the blood (an antibody found in the blood of most, but not all, people who have rheumatoid arthritis, as well as other rheumatic diseases)
Although the cause of psoriatic arthritis is unknown, factors such as immunity, genetics, and the environment may play a role.
The skin condition, psoriasis, may actually precede or follow psoriatic arthritis. The following are the most common symptoms of psoriatic arthritis. However, each child may experience symptoms differently. Symptoms may include:
- inflamed, swollen, and painful joints, usually in the fingers and toes
- reddened skin over the infected joint(s)
- deformed joints from chronic inflammation
- pitting of fingernails or toenails
As stated above, psoriasis may occur either before or after the onset of psoriatic arthritis. Some symptoms of psoriasis may include a scaly, pinkish-red, itchy rash on the knees, elbows, scalp, face, and folds of the buttocks.
Symptoms of psoriatic arthritis may resemble other medical conditions or problems. Always consult your child's physician for a diagnosis.
ESR is a measurement of how quickly red blood cells fall to the bottom of a test tube. When swelling and inflammation are present, the blood's proteins clump together and become heavier than normal. Thus, when measured, they fall and settle faster at the bottom of the test tube. Generally, the faster the blood cells fall, the more severe the inflammation.
If psoriasis has been diagnosed before or at the time the other symptoms of psoriatic arthritis are found, a diagnosis of psoriatic arthritis may be easily confirmed. However, when psoriatic arthritis symptoms precede symptoms of psoriasis, diagnosis is more difficult. Although psoriatic arthritis sometimes causes an elevated erythrocyte sedimentation rate (ESR), mild anemia, and elevated blood uric acid levels, these symptoms are also associated with other rheumatic diseases, including gout.
Other diagnostic tests may include:
- physical examination and history
- laboratory tests, such as blood tests
- x-rays - a diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.
Specific treatment for psoriatic arthritis will be determined by your child's physician based on:
- your child's overall health and medical history
- extent of the condition
- your child's tolerance for specific medications, procedures, and therapies
- expectation for the course of the disease
- your opinion or preference
Treatment usually involves treating both the skin condition and the joint inflammation. Some medications used to treat rheumatoid arthritis are also used to treat psoriatic arthritis, including:
- nonsteroidal anti-inflammatory medications, NSAIDs (to relieve symptoms)
- slow-acting medications (to slow bone deformation)
- immunosuppressive medications, such as methotrexate, if NSAIDs are not effective (to suppress inflammation)
Other treatment may include:
- corticosteroids (for inflammation)
- light treatment (UVB or PUVA)
- heat and cold
- physical therapy (to improve and maintain muscle and joint function)
- occupational therapy (to improve ability to perform activities of daily living)
- dermatology management of psoriasis skin rash, if present
- surgery (to repair or replace a damaged joint; if warranted, this usually occurs years after the initial diagnosis)
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Online Resources of Pediatric Arthritis & Other Rheumatic Diseases