Septic arthritis in a patient with juvenile rheumatoid arthritis.

The acute flare of joint inflammation in the child with known juvenile rheumatoid arthritis causes concern primarily regarding the need for additional or modified medical treatment. Acute joint inflammation in an otherwise healthy child creates concern regarding the existence of joint infection. In the early phase of disease, the clinical findings and symptoms of an inflamed joint attributable to juvenile rheumatoid arthritis or infection may be similar and difficult to differentiate from the other. Juvenile rheumatoid arthritis usually is well controlled by medical interventions, however, the initiation of specific treatment is more urgent in children with joint sepsis. The following case report is presented to emphasize the difficulty in evaluation of patients with known juvenile rheumatoid arthritis and coexistent septic arthritis, and to discuss the methods used to differentiate between the two conditions.