Not everyone who has psoriasis will get psoriatic arthritis, even though the conditions are often related.
Psoriasis causes patches of scaly, red, or white skin called plaques. Psoriatic arthritis sets off joint swelling and pain that can lead to permanent damage. Your immune system is responsible for both.
Symmetric psoriatic arthritis affects several joints in pairs on both sides of your body, like both elbows or both knees. It can be mild to severe. It destroys your joints over time, and they may stop working. That's why you need treatment. For about half of people with this type, it can be disabling. The symptoms of symmetric psoriatic arthritis looks like rheumatoid arthritis.
Asymmetric psoriatic arthritis typically affects only a few joints. They can be large or small and anywhere in your body. Fingers and toes may swell like sausages.
Distal interphalangeal predominant (DIP) psoriatic arthritis mainly affects small joints at the ends of the fingers and toes, as well as the nails. Sometimes it's confused with osteoarthritis, what most people think of when they hear "arthritis," when the cartilage and bone in the joints wears away.
Spondylitis affects the backbone. It can cause inflammation and stiffness between your vertebrae -- the bones of your neck, spine, and lower back -- and pelvis. Spondylitis can also attack ligaments that connect muscles to bones and other connective tissue.
Arthritis mutilans is the most severe and destructive form of psoriatic arthritis. Fortunately, it's rare. It damages the small joints in your fingers and toes so badly that they become deformed.
We don't know exactly why some people get the condition and others don't, but it seems to run in families. As many as 40% of people with psoriatic arthritis have a family member with skin or joint problems.
Up to a third of people who have psoriasis will get psoriatic arthritis. Psoriasis is a skin disease that causes a red, scaly rash, often over the elbows, knees, ankles, feet, and hands. It can also affect your nails. Both of these diseases happen because your immune system attacks your body instead of something from outside.
Psoriatic arthritis usually shows up between ages 30 and 50, but it may start in childhood. Both men and women get it. Many people have the skin disease first, but not everyone will.