Psoriatic arthritis is a spondyloarthritis and a form of joint inflammation that occurs in some people who have psoriasis of the skin or nails.
Joint inflammation can develop in people who have psoriasis.
Joints commonly involved include the hips, knees, fingers, and toes.
The diagnosis is based on symptoms.
Psoriatic arthritis resembles rheumatoid arthritis but does not produce the antibodies characteristic of rheumatoid arthritis. Psoriatic arthritis occurs in about 20% of people with psoriasis (a skin condition causing flare-ups of red, scaly rashes and thickened, pitted nails). People with a certain gene (HLA-B27) and those who have affected family members are at increased risk of psoriatic arthritis of the spine. The cause of psoriatic arthritis is unknown.
Symptoms of Psoriatic Arthritis
In psoriatic arthritis, inflammation often affects joints closest to the tips of the fingers and toes, although other joints, including the hips, knees, and spine, are often affected as well. Often, the joints of the upper extremities are affected more. Back pain may be present.
The joints may become swollen and deformed when inflammation is chronic. Psoriatic arthritis affects joints asymmetrically (more on one side of the body than the other), more so than rheumatoid arthritis, and involves fewer joints. Tendons or ligaments can become inflamed where they attach to bone around the joints (called enthesitis). Some people who have psoriatic arthritis also have fibromyalgia, which causes muscle pain, joint stiffness, and fatigue.
The psoriasis rash may appear before or after arthritis develops. Sometimes the rash is not noticed because it is hidden in the scalp, navel, or creases of the skin such as between the back of the buttocks and thigh. The skin and joint symptoms sometimes appear and disappear together and sometimes they do not. Sometimes the skin symptoms are more severe than the joint symptoms, and sometimes the joint symptoms are more severe.
This image shows swelling of joint closest to the fingertip (distal interphalangeal joint) in a person with psoriatic arthritis.
Image courtesy of Kinanah Yaseen, MD.
This photo shows dactylitis or sausage digits, so-called because the swelling causes the fingers to take on a sausage-shaped appearance, in a person who has psoriatic arthritis. Pitting of the nails and salmon-colored patches on the skin are also visible.
© Springer Science+Business Media
This photo shows red, flaky, and thickened skin on the scalp of a person who has psoriasis.
DR P. MARAZZI/SCIENCE PHOTO LIBRARY
This photo shows red patches covered with silvery-white scales on the elbows of a person who has psoriasis.
SCIENCE PHOTO LIBRARY
This image shows swelling of joint closest to the fingertip (distal interphalangeal joint) in a person with psoriatic arthritis.
Image courtesy of Kinanah Yaseen, MD.
This photo shows dactylitis or sausage digits, so-called because the swelling causes the fingers to take on a sausage-shaped appearance, in a person who has psoriatic arthritis. Pitting of the nails and salmon-colored patches on the skin are also visible.
© Springer Science+Business Media
This photo shows red, flaky, and thickened skin on the scalp of a person who has psoriasis.
DR P. MARAZZI/SCIENCE PHOTO LIBRARY
This photo shows red patches covered with silvery-white scales on the elbows of a person who has psoriasis.
SCIENCE PHOTO LIBRARY
Diagnosis of Psoriatic Arthritis
Blood tests
X-rays
The diagnosis of psoriatic arthritis is made by identifying the characteristic joint inflammation in a person who has arthritis and psoriasis. Doctors also ask people whether they have a family history of psoriasis.
There are no tests to confirm the diagnosis, but blood tests for rheumatoid factor are done to exclude rheumatoid arthritis, and x-rays are done to show the extent of joint damage.
Treatment of Psoriatic Arthritis
Tumor necrosis factor inhibitors
Treatment of psoriatic arthritis is aimed at controlling the rash and relieving the joint inflammation. Several medications that are effective in treating rheumatoid arthritis (see table Medications for Rheumatoid Arthritis) are also used to treat psoriatic arthritis, particularly nonsteroidal anti-inflammatory drugs (NSAIDs), conventional synthetic DMARDsbiologic agents.
Biologic agents are made from living organisms and inhibit certain chemicals involved in the immune system. They include tumor necrosis factor (TNF) inhibitors
Prognosis for Psoriatic Arthritis
The prognosis for psoriatic arthritis is usually better than that for rheumatoid arthritis because fewer joints are affected. Nonetheless, the joints can be severely damaged.
More Information
The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.
Arthritis Foundation: Information about psoriatic arthritis and available treatments, lifestyle tips, and other resources
