When skin psoriasis is accompanied by joint pain or swelling, it may be a sign of psoriatic arthritis. Arthritis symptoms can show up many years after psoriasis symptoms. Occasionally, joint symptoms can precede the skin condition.
15% of people develop psoriatic arthritis symptoms first and psoriasis develops later—or not at all (and may experience only nail changes).1
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Subtypes of Psoriatic Arthritis
Researchers have identified 5 different subtypes of psoriatic arthritis. These subtypes are based on the symptoms the person is experiencing. It is common to have more than one subtype.
- Asymmetric psoriatic arthritis, also known as oligoarticular psoriatic arthritis, affects 1 to 4 joints. Large joints, such as the knee, are typically affected. This subtype of psoriatic arthritis is more common in men.
- Symmetric psoriatic arthritis, also known as polyarticular psoriatic arthritis, causes symptoms in 5 or more joints. Small joints in the hands and/or feet are typically among the joints affected. As its name implies, symmetric psoriatic arthritis commonly affects joints symmetrically, meaning if the middle finger of the left hand is affected, the middle finger on the right hand is also affected. This subtype occurs more often in women than in men. It can look very similar to rheumatoid arthritis.
- Distal psoriatic arthritis affects the last joints in the fingers, toes, or both. People who have it usually also have another subtype. This subtype is also referred to as distal interphalangeal predominant arthritis.
- Arthritis mutilans involves degenerative changes to the bones. This severe form of psoriatic arthritis may result in deformities. For example, affected fingers may become shorter and/or crooked.
- Axial arthritis or spondyloarthritis affects one or more parts of the spine, including the neck and sacroiliac joints. It can also affect the hips.
Evidence suggests subtypes are influenced by genetics. The treatment for psoriatic arthritis may vary depending on the subtype.