Lecture on Juvenile Idiopathic Arthritis (JIA)

Case Study

• Patient: 11-year-old child
• Symptoms: Long-standing pain and swelling of fingers, wrists, and ankles
• Diagnosis: Likely Juvenile Idiopathic Arthritis (JIA)

Overview of JIA

• Definition: Autoimmune disease causing pain and swelling in joints
• Primary Age Group: Children, onset typically before 16 years of age

Major Types of JIA

1. Oligoarticular JIA

   • Affects fewer than six joints
   • Medium and large joints, usually asymmetric
   • More common in females
   • Onset: Typically ages 2-3, rarely after age 10
   • Groups:
     • ANA-positive: Higher risk of uveitis (~20%)
     • ANA-negative: Lower risk of uveitis
   • Generally non-destructive, no systemic features

2. Polyarticular JIA

   • Affects multiple joints, symmetric
   • More common in females
   • Onset: Most common ages 2-5 and 10-14
   • Symptoms: Hands, feet, ankles typically involved, destructive arthritis
   • Less frequent uveitis

3. Systemic JIA

   • Can affect any joints or no joints
   • Onset: Any age under 17, no gender predominance
   • Symptoms: High daily fevers, evanescent salmon-pink rash, hepatosplenomegaly, lymphadenopathy, heart/lung/liver involvement
   • Often destructive arthritis

Less Common Types of JIA

• Enthesitis-associated JIA: Inflammation at insertion points around joints
• Psoriatic JIA: Associated with psoriasis of the skin
• Undifferentiated JIA: Does not fit into other categories

Pathophysiology

• Target: Synovium
• Process: Auto-inflammatory response leading to proliferation of synovial tissue, increased joint fluid, and swelling
• Symptoms Progression: Persistent synovitis → Joint destruction → Long-term bone, tendon, ligament issues

Diagnostic Considerations

• History: Joint pain, morning stiffness, stiffness after inactivity (gelling), limp
• Signs: 25% of patients may have no pain, only swelling
• Systemic JIA: Look for systemic symptoms such as fever and rash

Visuals and Examples

• Symptom Picture: Chronic joint destruction in polyarticular JIA (example of 4-year-old affected sister)
• Rash: Salmon-pink rash in systemic JIA (rare, not always present)