Types of Juvenile Rheumatoid Arthritis

• Pauciarticular: Pauciarticular (paw-see-are-tick-you-lar) means that four or fewer joints are affected. Pauciarticular is the most common form of JRA; about half of all children with JRA have this type. Pauciarticular disease typically affects large joints, such as the knees. Girls under age 8 are most likely to develop this type of JRA.
  
  Some children have special proteins in the blood called antinuclear antibodies (ANAs). Eye disease affects about 20 to 30% of children with pauciarticular JRA. Up to 80% of those with eye disease also test positive for ANA, and the disease tends to develop at a particularly early age in these children. Regular examinations by an ophthalmologist (a doctor who specializes in eye diseases) are necessary to prevent serious eye problems such as iritis (inflammation of the iris) or uveitis (inflammation of the inner eye, or uvea).
  
  Many children with pauciarticular disease outgrow arthritis by adulthood, although eye problems can continue and joint symptoms may recur in some people.
  
  
• Polyarticular: About 30% of all children with JRA have polyarticular disease. In polyarticular disease, five or more joints are affected. The small joints, such as those in the hands and feet, are most commonly involved, but the disease may also affect large joints. Polyarticular JRA often is symmetrical; that is, it affects the same joint on both sides of the body.
  
  Some children with polyarticular disease have a special kind of antibody in their blood called IgM rheumatoid factor (RF). These children often have a more severe form of the disease, which doctors consider to be the same as adult rheumatoid arthritis.
  
  
• Systemic: Besides joint swelling, the systemic form of JRA is characterized by fever and a light pink rash, and may also affect internal organs such as the heart, liver, spleen, and lymph nodes. Doctors sometimes call it Still's disease. Almost all children with this type of JRA test negative for both RF and ANA. The systemic form affects 20% of all children with JRA. A small percentage of these children develop arthritis in many joints and can have severe arthritis that continues into adulthood.
  
  

Material provided by the National Institute of Arthritis and Musculoskeletal and Skin Diseases. You may visit their website at www.nih.com.