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The term juvenile idiopathic arthritis (JIA), formerly known as juvenile rheumatoid arthritis, describes several subtypes of chronic childhood arthritis further classified by number of joints involved and other clinical characteristics. Oligoarticular JIA (less than five joints involved) and polyarticular JIA (five or more joints involved) patients generally present with joint swelling with painful, limited range of motion that persists for more than 6 weeks. Joints may be warm but are not typically erythematous. The onset is usually insidious, but these patients may present to the ED with concern for mechanical injury or infection. Systemic JIA (known as Still disease in adults) is an important distinct category of disease characterized by arthritis in addition to a classic daily fever (often spiking in the evening) with accompanying erythematous macular rash that tends to worsen with the fever. Patients with systemic JIA are at risk for developing macrophage activation syndrome, especially early in the disease course and with infections.
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Management and Disposition
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JIA should be considered in patients with joint effusion and limited range of motion, especially if symptoms have been chronic. Basic plain films can be performed to rule out many traumatic or mechanical causes, and if history of symptoms is chronic, patients with suspected JIA can be referred to follow-up with rheumatology as an outpatient. Acute onset of these symptoms should raise suspicion for infection or mechanical injury, and arthrocentesis or MRI should be considered. Patients with systemic JIA presenting to the ED with fever should have complete blood count (CBC), erythrocyte sedimentation rate (ESR), ferritin, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) drawn to evaluate for macrophage activation syndrome (cytopenias, markedly elevated ferritin, elevated AST/ALT), which can be life threatening. Patients treated with immunosuppressing systemic therapy for JIA (often methotrexate or biologic medications) should have careful evaluation of fever as well, and medications should be held during febrile illnesses.
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Young patients with JIA may not complain of pain; often the presenting symptoms are swelling and functional changes, such as a limp.
All patients with systemic JIA who present with fever should have workup for CBC, ferritin, ESR, AST, and ALT to evaluate for macrophage activation syndrome.
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