Juvenile Idiopathic Arthritis

Snapshot

• A 9-year-old girl presents to his pediatrican’s office by his mother due to fever and joint pain. The mother reports that she has been having knee and wrist pain for approximately 7 weeks. Her pain is worse in the morning and is associated with swelling of the affected joint. She develops a fever daily that later subsides. On physical exam, there is tenderness to palpation of the affected joint. Laboratory studies are significant for an elevated ANA, ESR, and CRP. She is negative for rheumatoid factor.

Introduction

• Clinical definition
  • a broad term that encompasses different types of pediatric chronic arthritis that is characterized by joint pain and inflammation
    • 1 or more joints are involved for at least 6 weeks in patients < 16 years of age
    • subtypes
      • polyarticular juvenile idiopathic arthritis (JIA)
        • ≥ 5 joints involved
      • pauciarticular JIA
        • 1-4 joints involved
      • systemic JIA
        • visceral involvement
• Epidemiology
  • incidence
    • the most common chronic rheumatologic disorder in children
  • demographics
    • more frequently with European ancestry
• Pathogenesis
  • not well understood but may involve both genetic and environmental factors
    • the humoral and cell-mediated immune system are involved
      • T-cells release tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IL-1
      • the humoral immune system is involved by increasing antinuclear antibody (ANA) production, immunoglobulins, and circulating immune complexes
• Prognosis
  • postitive
    • improved with advances in treatment
  • negative
    • early hip or wrist involvement
• presence of rheumatoid factor

Presentation

• Symptoms
  • fever
    • quotidian pattern
      • fevers occurring once or twice per day that eventually subside
  • morning stiffness and joint pain
    • joint stiffness and pain can also be noted with prolonged periods of inactivity (e.g., sitting)
  • visual changes
    • can be suggestive of a uveitis
• Physical exam
  • joint involvement
    • swelling
    • limited range of motion
    • tenderness to palpation
  • uveitis 
  • visceral involvement in cases of systemic JIA such as
    • evanescent and salmon-colored macular rash
    • hepatosplenomegaly
    • serositis
• e.g., pleural and pericardial effusion

Studies

• Labs
  • ↑ c-reactive protein (CRP) and erythrocyte sedimentation rate (ESR)
    • typically in systemic and polyarticular JIA
  • positive ANA
    • in most cases
• Diagnostic criteria
• a patient < 16 years of age with 1 or more joints involved for at least 6 weeks

Differential

• Reactive arthritis
• Rheumatoid arthritis
• Systemic lupus erythematosus
• Leukemia
• Pediatric sarcoidosis

Treatment

• Conservative
  • period ophthalmologic exams
    • indication
      • for monitoring of eye involvement (e.g., uveitis)
• Medical
  • nonsteroidal antiinflammatory drugs (NSAIDs)
    • indication
      • for symptomatic relief
  • disease-modifying antirheumatic drugs (DMARDs)
    • indication
      • for controlling inflammatory process
    • medication
      • methotrexate
      • etanercept
      • adalimumab
  • intra-articular glucocorticoids
    • indication
• effective in managing inflamed joint

Complications

• Infection
• Macrophage-activation syndrome
• Pericarditis
• Hemolytic anemia
• Enarteritis