Polyarticular Juvenile Idiopathic Arthritis (Polyarthritis)

Polyarticular juvenile idiopathic arthritis (JIA), also known as polyarthritis, affects 5 or more joints during the first 6 months of symptoms. This type of JIA is more severe than oligoarticular JIA, because it affects more joints and tends to get worse over time. Polyarticular JIA often begins in large joints, such as...