Psoriatic arthritis (PA) is an inflammatory autoimmune joint condition that develops in some people who have psoriasis, a common condition that causes inflamed, scaly skin.. It most often affects adults in their 30s through 50s, but children can develop a form of the disease called juvenile psoriatic arthritis.

PA manifests in several forms, and symptoms can range from mild to severe. Fingers and toes are the areas of the body most commonly affected. Many patients also experience pitted, discolored nails and inflammatory eye conditions such as conjunctivitis.

PA develops in about 15 percent of psoriasis patients, with the joint inflammation caused by the immune system's overreaction to the skin disease, according to the American College of Rheumatology. Psoriasis affects 2.5 percent of the white population in North America but is less prevalent in the African American and Native American populations.

PA is usually less crippling than some other forms of arthritis such as rheumatoid arthritis. However, left untreated, PA can cause disability and deformity. About 20 percent of patients with PA have a severe form of the disease that is potentially deforming and debilitating, according to the Arthritis Foundation (AF).

There is no known cure for PA, but medication, physical therapy and lifestyle changes often can relieve pain and slow the disease’s progression.