title: Rheumatic fever presenting as monoarticular arthritis.
abstract: BACKGROUND
  Monoarticular arthritis in children is most often suppurative septic arthritis (SA) of bacterial origin. We recently cared for 3 patients with monoarticular arthritis who developed carditis while receiving antibiotics for SA. Distinguishing SA from rheumatic fever (RF) is critical to avoid lifelong cardiac complications associated with RF.
  
  
  METHODS
  We compared the 3 cases of RF presenting with monoarticular arthritis with 12 cases of culture-confirmed SA to assess the clinical and laboratory differences between the 2 groups.
  
  
  RESULTS
  Erythrocyte sedimentation rate, C-reactive protein and mean synovial fluid white blood cell counts were elevated in both groups. Mean antistreptolysin O (ASO) and anti-DNase B titers were elevated in patients with RF.
  
  
  CONCLUSIONS
  The clinical and laboratory features of RF and SA demonstrate substantial overlap. Patients with monoarticular arthritis and sterile synovial fluid cultures should have RF included in their differential diagnoses. Patients with an elevated ASO and/or anti-DNase B titer should have a careful cardiac examination looking for clinical evidence of carditis. Echocardiogram should be considered if clinical carditis associated with RF is suspected.
authors.affiliation: Division of Pediatric Inpatient Medicine, Department of Pediatrics, University of Utah, Salt Lake City, Utah 84113, USA. gregory.harlan@hsc.utah.edu
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Harlan
authors.forename: Lloyd Y
authors.initials: LY
authors.lastname: Tani
authors.forename: Carrie L
authors.initials: CL
authors.lastname: Byington
mesh_terms: D000293:Adolescent; D001170:Arthritis, Infectious / Q000175:diagnosis* / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D012213:Rheumatic Fever / Q000175:diagnosis* / Q000453:epidemiology; D014481:United States / Q000453:epidemiology