Jane Young is a 3 1/2 year-old girl, brought to the Pediatric Medicine Clinic by her mother. For the past 10 days, her right knee has been swollen and stiff. There was no preceding trauma. She seems to have most symptoms in the morning, getting better when she is up and about playing. She seems to have less energy since the swelling was first noted. Her mother has been giving her children's Tylenol but has not noticed any improvement in her symptoms. Her mother thinks her ankles are also "puffy" at times. On examination, Jane appears well, afebrile and is on the 50th percentile for height and weight. No fever or skin rashes. Cardiovascular, respiratory and abdominal examinations unremarkable. Right knee is swollen, warm and effused and Jane stands with this knee slightly flexed. There are mild effusions of both ankles which are also slightly swollen. The pediatrician decides to order a few investigations. Baseline CBC, renal and liver function is unremarkable. ESR moderately elevated at 30. Rheumatoid Factor is negative, but Antinuclear Antibody (ANA) is positive at 1:160.