Doctors classify three kinds of JRA by the number of joints involved, the symptoms, and the presence or
absence of certain antibodies in the blood. (Antibodies are special proteins made by the immune system.)
These classifications help the doctor determine how the disease will progress.
Pauciarticular (paw-see-are-tick-you-lar):
Pauciarticular 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 percent of children with pauciarticular JRA. Up to 80 percent 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 percent 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 percent of all children with JRA. A small percentage of these children develop arthritis in
many
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