Juvenile Rheumatoid Arthritis (JRA)
Are There Different Types of Juvenile Rheumatoid Arthritis?
Doctors classify three kinds of JRA. Each type is based on the number of joints involved, the symptoms, and the presence of certain antibodies in the blood. These three different classifications help determine how the disease will progress.
Pauciarticular (paw-see-are-tick-you-lar) means that four or fewer joints are involved. This is the most common form of JRA; about half of all children with JRA have this type.
This type of JRA typically affects large joints, such as the knees. Girls under age 8 are most likely to develop this type of JRA. Some children with pauciarticular JRA have special proteins in the blood called antinuclear antibodies (ANAs).
Eye disease affects from 20% to 30% of children with pauciarticular JRA and is more common in children with ANAs. Regular exams by an ophthalmologist (a doctor specializing in eye diseases) are necessary with JRA.
The ophthalmologist treats serious eye problems such as iritis (inflammation of the iris, the colored part of the eye) or uveitis (inflammation of the inner eye). Many children with pauciarticular disease outgrow JRA by adulthood. Still, eye problems can continue and joint symptoms may recur in some people.
About 30% of all children with JRA have polyarticular disease, in which five or more joints are affected. The small joints, such as those in the hands and feet, are most commonly involved. However, the disease may also affect large joints.
Polyarticular JRA often is symmetrical. This means it affects the same joints on both sides of the body. Some children with polyarticular disease have rheumatoid factor in their blood. These children often have a more severe form of the disease. Doctors consider this to be the same as adult rheumatoid arthritis.
Along with joint swelling, the systemic form of JRA is characterized by fever and a light pink rash. This type of JRA may affect internal organs such as the heart, liver, spleen, and lymph nodes.
The systemic form (called Still's disease) affects 20% of children with JRA. Almost all children with this type of JRA test negative for both rheumatoid factor and ANA.
A small percentage of these children with systemic JRA develop arthritis in many joints. They may have severe arthritis that continues into adulthood.