RT Book, Section A1 Prahalad, Sampath A2 Zaoutis, Lisa B. A2 Chiang, Vincent W. SR Print(0) ID 1146122484 T1 Juvenile Idiopathic Arthritis T2 Comprehensive Pediatric Hospital Medicine, 2e YR 2017 FD 2017 PB McGraw-Hill Education PP New York, NY SN 9780071829281 LK accesspediatrics.mhmedical.com/content.aspx?aid=1146122484 RD 2024/03/28 AB Arthritis is inflammation of synovial tissue within a diarthrodial joint*. Infection-related arthritides are discussed in Chapter 152, but idiopathic arthritides constitute another group. Because the pathogenesis of the idiopathic forms is not completely understood, a variety of schemes have been devised to classify childhood arthritides according to the pattern of involvement, associated symptoms, and genetic factors. The classification criteria for juvenile idiopathic arthritis (JIA) proposed by the International League of Associations for Rheumatology is the most current,1 and is followed in this chapter. Based on the number of inflamed joints, laboratory features, family history, and extra-articular features, seven subtypes are recognized: oligoarticular arthritis, rheumatoid factor (RF)-positive polyarthritis, RF-negative polyarthritis, systemic onset JIA, enthesitis-related arthritis (ERA), psoriatic arthritis, or undifferentiated arthritis (Table 150-1).