RT Book, Section A1 Bongartz, Timothy A1 Dingle, Jodi A. A2 Knoop, Kevin J. A2 Stack, Lawrence B. A2 Storrow, Alan B. A2 Thurman, R. Jason SR Print(0) ID 1181053208 T1 Juvenile Idiopathic Arthritis T2 The Atlas of Emergency Medicine, 5e YR 2021 FD 2021 PB McGraw-Hill PP New York, NY SN 9781260134940 LK accessmedicine.mhmedical.com/content.aspx?aid=1181053208 RD 2024/10/08 AB 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.