Snapshot A 3-year-old boy presents to the emergency department due to worsening joint pain, fever, and a new rash. He is accompanied by his mother who reports that he has been pointing at his knee and hip while crying. She believes he has been having this symptom for approximately 2 months. He has been having 1-2 fevers a day, and she reports seeing a "pink-like" rash. On physical exam, there is an evanescent salmon-colored rash on the left thigh. There is tenderness to palpation of the left knee and hip with limited range of motion. Lab results show an elevated ESR, CRP, and positive ANA. A pediatric rheumatologist is consulted for further evaluation. Introduction Clinical definition login to view 9 more bullets Epidemiology Incidence login to view 1 more bullet Demographics login to view 1 more bullet ETIOLOGY Pathogenesis login to view 4 more bullets Presentation Symptoms login to view 7 more bullets Physical exam login to view 10 more bullets Imaging Radiography login to view 2 more bullets Studies Labs login to view 4 more bullets Diagnostic criteria login to view 1 more bullet Differential Reactive arthritis Rheumatoid arthritis Systemic lupus erythematosus Leukemia Pediatric sarcoidosis Still disease (in older patients) login to view 1 more bullet Treatment Conservative login to view 3 more bullets Medical login to view 13 more bullets Complications Infection Macrophage-activation syndrome Pericarditis Hemolytic anemia Enarteritis Prognosis Postitive login to view 1 more bullet Negative login to view 2 more bullets