JUVENILE RHEUMATOID ARTHRITIS (Systemic Onset)

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JUVENILE RHEUMATOID ARTHRITIS (Systemic Onset)

http://arthritis.about.com/gi/dynamic/offsite.htm?site=http://www.mc.vanderbilt.\

edu/peds/pidl/rheum/jra.htm

Juvenile rheumatoid arthritis is a chronic inflammatory disease that

always involves the joints, but may produce extensive connective tissue

and visceral lesions. Despite extensive research the etiology of JRA

remains unclear. JRA is arbitrarily defined as beginning before the age

of 16 years. Approximately 20% have acute systemic JRA which is

characterized by febrile onset, variable joint manifestations, rash,

generalized

lymphadenopathy, splenomegaly, liver disease, and rarely by GI tract

disease. Other children with JRA primarily have arthritis that is

present at the onset of illness. In 30% only a single joint, usually the

knee, is involved; in 50% multiple joints are involved. The disease is

termed polyarticular if more than 4 joints are involved and

pauciarticular if 4 or fewer joints are affected. The acute systemic

onset of JRA is often referred to as Still's disease because of Still's

classic description of the disease in 1897.

The systemic symptoms of JRA may precede the onset of overt arthritis

for a variable periods of time ranging from months to years. The most

characteristic features of systemic JRA are a high-spiking fever and the

rheumatoid rash. The temperature peaks once or twice daily, often in the

late afternoon or evening, to a level of 39oC or higher with a rapid

return to baseline which might be a sub-normal temperature. Chills are

frequent at the time of the fever though rigors rarely occur. These

children often appear quite ill while febrile but surprisingly well

during the rest of the day. These fevers may respond poorly to

anti-pyretics (including aspirin). In some instances, the fever responds

only to steroid therapy.

The fever in systemic JRA is almost always accompanied by the classic

rheumatoid rash. This consists of 2mm-5mm erythematous morbilliform

macules most commonly seen on the trunk and proximal extremities though

it may occur on the face, palms, or soles. The rash is non-pruritic but

most characteristic is its transient and migratory nature. A single

lesion rarely persists for more than an hour. The rash may be seen in a

small number of patients with polyarthritis at onset but never with

oligoarthritis without other systemic symptoms. The rash can be elicited

by rubbing or scratching the skin - the Koebner's phenomenon, or may be

elicited during a hot bath or with psychological stress.

Children with the systemic onset of JRA usually have lymphadenopathy and

hepatosplenomegaly accompanying their active disease. Other organ

systems may become involved (i.e., pericarditis, or much less commonly

hepatitis, pulmonary interstitial fibrosis or central nervous system

involvement).

Systemic onset JRA does not have a peak age for occurrence in childhood,

and appears to effect males and females with equal frequency. About half

the children with systemic onset JRA recover nearly completely in time

while the other half show progressive involvement of more joints with

moderate to severe disability. The presence of arthritis must be

confirmed to make a definite diagnosis of JRA and thus usually occurs

within the first year of suspected diagnosis.

Laboratory tests are not helpful in confirming the diagnosis of Still's

Disease. Both the ANA and Rheumatoid Factor are usually negative and

there is no association with HLA-B27. Antinuclear antibody may be

positive, if so, it is often in a speckled pattern. A positive ANA is

found in young females with pauciarticular arthritis who are at risk for

developing iridocyclitis. The differential diagnosis includes acute and

chronic

infection, malignancy, Kawasaki's disease, inflammatory bowel disease,

rheumatic fever, and SLE.

(Some repetetive wording, same as in previous article about

pauciarticular JRA, snipped to save space).

Chronic uveitis is a perplexing complication of JRA which occurs most

commonly in young girls with oligoarthritis and ANA seropositivity.

Around 1/4 of patients with oligoarthritis develop uveitis. In children

with chronic uveitis approximately 60% have complete recovery of normal

sight, 25% have impaired vision or unilateral blindness, and

approximately 10% are blind. Children with systemic JRA rarely develop

chronic uveitis (<1%).

REFERENCES

Cassidy, J. Textbook of Pediatric Rheumatology, Churchill-Livingstone,

1990.

Ammann, A. Juvenile Rheumatoid Arthritis, in Rudolph, Pediatrics, 1991.

Schiller, D. Juvenile rheumatoid arthritis - A review. Pediatrics 50:

940, 1970.