Juvenile Idiopathic Arthritis

Pauciarticular (4 or fewer joints involved)
1. Age at presentation <8 years
2. Involves large joints and is typically asymmetric
3. Boys may develop Sacroiliitis
4. Iridocyclitis may be present
Polyarticular (>4 joints involved)
1. Age at presentation 1-6 or 11-16 years
2. Involves small joints with symmetric involvement
3. Rheumatoid Factor may be positive
  1. Positive Rheumatoid Factor confers similar presentation to Rheumatoid Arthritis in adults
Systemic (Still's Disease)
1. High daily Relapsing Fever >39 degrees persists over 2 weeks (most distinguishes this type from others)
2. Polyarticular involvement with >4 joints involved
3. Hepatomegaly and Splenomegaly
4. Lymphadenopathy
5. Pleural Effusion or Pericardial Effusion may be present
6. Recurrent evanescent rash
  1. Faint salmon colored rash over trunk, palms and soles

Pediatric Limp (most common presentation)
Pain is minimal compared to inflammatory signs
1. Increasing pain has Negative Predictive Value for RA

Similar to adult form of Rheumatoid Arthritis
1. Joint Swelling with warmth (not red and hot)
Differences from Adult Rheumatoid Arthritis
1. Higher fever
2. Rheumatoid Nodules are rare
3. Pericarditis and valvulitis are more common
4. Lymphadenopathy and Hepatosplenomegaly are common
5. Arthritis interferes with bone growth
  1. Example: underdeveloped Mandible
6. Uveitis most common juvenile RA eye disorder
  1. Occurs in up to 50% of Pauciarticular juvenile RA
    1. Highest risk if ANA positive and recent onset
  2. Asymptomatic in up to 80% of cases
  3. Delayed diagnosis risks Cataracts, Glaucoma, blind
  4. Ophthalmology should follow all with juvenile RA

Precautions
1. Rheumatoid Factor and Antinuclear Antibody are negative in more than 80% of juvenile RA
Rheumatoid Factor
1. Variably positive, often normal
Antinuclear Antibody
1. May be associated with Uveitis (see above)
Erythrocyte Sedimentation Rate (ESR)
1. High ESR may suggest other diagnoses (e.g. infection)
C-Reactive Protein (CRP)
Complete Blood Count
1. Abnormal in systemic presentation

Obtain labs (normal findings do not exclude flare)
1. Complete Blood Count with differential
2. Erythrocyte Sedimentation Rate
3. C-Reactive Protein (CRP)
Associated serious conditions
1. Infection
  1. CD-20 Cytolytic Monoclonal Antibody (e.g. Rituxamab) result in Immunocompromised state
  2. Labs as above and consider Lactic Acid and Blood Cultures
  3. Exclude serious infection and treat obvious causes
  4. Stop Monoclonal Antibody or other Immunosuppressants until infection resolves
2. Septic Joint
  1. Febrile patient with red, hot joint and increased CRP and ESR
  2. Joint Aspiration if unclear diagnosis
3. Macrophage activation syndrome
  1. Cytokine "storm" with similar appearance to Sepsis, with risk of DIC, Acute Renal Failure, Pancytopenia
  2. Treated with high dose pulse Corticosteroids and supportive care
Symptomatic flare management
1. NSAIDs
  1. First-line treatment for mild to moderate Arthritis symptoms if not taken consistently
2. Corticosteroids
  1. Second-line treatment for moderate to severe Arthritis symptoms, especially if NSAID refractory
  2. Prednisolone 1-2 mg/kg orally divided twice daily for 3-5 days
    1. Consider initial dose of Methylprednisolone 1-2 mg/kg IV if in Emergency Department
3. Hospitalization indications
  1. Inability to ambulate
  2. Concurrent serious infection

Immunomodulating agents significantly improve longterm outcomes with less chronic Disability