Psoriatic arthritis is a genetically determined autoimmune disease that occurs in less than 10 percent of persons with psoriasis. Its treatment often requires consultation with a rheumatologist in addition to treatment of the skin lesions by a dermatologist. Psoriatic arthritis is classified with the disease grouping called seronegative spondyloarthropathies which also includes ankylosing spondylitis, enteropathic arthritis, and Reiter’s Syndrome. It occurs most frequently in psoriasis patients whose disease is active, especially in persons with the pustular type of psoriasis. Occasionally it appears in a person who has no dermatologic signs or symptoms of psoriasis, in which case it must be diagnosed by its unique laboratory test results. Psoriasis of the fingernails and toenails is associated with a higher incidence of psoriatic arthritis.
Symptoms of psoriatic arthritis resemble those of rheumatoid arthritis, although the diseases are otherwise quite different. Arthritis changes cause deterioration and pain in small joints of the hands and feet, large joints of the legs and spine, and tendons. Nonspecific foot pain or "tennis elbow" may be an early symptom to appear and may be overlooked if not associated with psoriatic skin or nail lesions.
Confirmation of a diagnosis of psoriatic arthritis requires specific blood and serum tests to differentiate it from conditions such as rheumatoid arthritis and other autoimmune diseases.
Please see the National Psoriasis Foundation for information on the treatment of psoriatic arthritis.
A pediatric form of psoriatic arthritis may appear as early as age 2 to 4 years in girls. A peak period of pediatric onset is age 11 to 12 in both girls and boys. In children the arthritis may appear several years prior to the onset of psoriatic skin lesions; this may pose a problem in recognizing the nature of the underlying disease, especially if there is no known family history of psoriasis.
Although psoriatic arthritis and psoriasis occasionally occur in the absence of a history of psoriasis in the family, a genetic predisposition for psoriasis is considered to be a necessary condition for development of psoriatic arthritis. The evidence for inheritability is well established.
As in the case of psoriasis, an environmental "trigger" may initiate the development of psoriatic arthritis in a genetically predisposed person.
