PE21.5 | Juvenile Idiopathic Arthritis — Summary & Reflection

KEY TAKEAWAYS

Juvenile idiopathic arthritis (JIA) is defined by the ILAR criteria as arthritis of unknown cause with onset before age 16 years lasting ≥6 weeks, after exclusion of other causes. The seven ILAR subtypes differ in joint count, serology, and systemic features, with oligoarticular JIA being the most common (~50%) and a particular risk for chronic asymptomatic anterior uveitis in ANA-positive young girls.

Pathogenesis involves immune dysregulation: T-cell and cytokine-driven (TNF-α, IL-6 in oligoarticular/polyarticular; IL-1β in systemic JIA) synovial inflammation leading to pannus formation and potential joint destruction. Complications include uveitis (blindness if unscreened) and MAS in systemic JIA (haematological emergency with hyperferritinaemia and cytopenias).

Diagnosis is clinical and exclusionary: rule out septic arthritis (emergency), leukaemia, and reactive arthritis before committing to a JIA label. Investigations include ANA, RF, HLA-B27, CBC, ESR/CRP, and mandatory slit-lamp ophthalmology.

Management is stepwise: NSAIDs → intra-articular corticosteroids → methotrexate (anchor DMARD, 10–15 mg/m²/week) → biologics (TNF inhibitors for polyarticular/oligoarticular; tocilizumab/canakinumab for systemic JIA), with physiotherapy, ophthalmology surveillance, and growth monitoring throughout.

REFLECT

Consider the 7-year-old girl in the opening hook — swollen knee, morning stiffness, and asymptomatic posterior synechiae found incidentally on slit-lamp. Reflect on what would have happened if ophthalmology screening had not been arranged at that visit. How does this case change how you will approach any child with joint swelling in your future practice? Think about the systems-level question: in a busy paediatric OPD, how would you ensure that every newly diagnosed JIA patient — particularly an oligoarticular ANA-positive child — is actually enrolled in a scheduled slit-lamp follow-up programme and does not fall through the cracks? What barriers exist and how might they be addressed? Kolb's reflective cycle asks you to move from this concrete experience → reflective observation → abstract conceptualisation → active experimentation: what one concrete action will you take in your clinical practice to prevent uveitis-related blindness in a JIA patient?