PAEDIATRIC RHEUMATOLOGY

Juvenile Idiopathic Arthritis (JIA)

•    Definition: arthritis >6 weeks, onset <16 years, unknown cause

•    Subtypes:

o    Oligoarticular JIA:

    ≤4 joints affected (typically large joints like knee, ankle)

    Most common form

    High risk of uveitis

    ANA positive in ~70%

o    Polyarticular JIA:

    ≥5 joints affected

    Can be RF-positive or negative

    Resembles adult RA (especially if RF+)

o    Systemic JIA (Still’s disease):

    Daily quotidian fever, salmon-pink rash

    Arthritis + hepatosplenomegaly, lymphadenopathy, serositis

    Can cause macrophage activation syndrome (MAS) (life-threatening)

•    Investigations:

o    ANA (esp. for uveitis risk)

o    ESR/CRP (inflammatory markers)

o    FBC: anaemia of chronic disease, leukocytosis, thrombocytosis

o    Uveitis: slit lamp examination (may be asymptomatic)

•    Complications:

o    Chronic anterior uveitis (esp. in oligoarticular JIA + ANA+)

o    Growth delay, joint deformities

•    Management:

o    NSAIDs (symptomatic relief)

o    Intra-articular steroids

o    DMARDs: methotrexate if persistent or polyarticular disease

o    Biologics: e.g. anti-TNF if refractory

o    Ophthalmology monitoring for uveitis (even if asymptomatic)

Kawasaki Disease (Acute Febrile Vasculitis of Childhood)

•    Epidemiology: children <5 years, more common in boys and East Asian descent

•    Diagnostic criteria:

o    Fever ≥5 days + 4 of 5:

    Conjunctivitis (bilateral, non-purulent)

    Rash (polymorphous, non-vesicular)

    Oral changes (e.g. strawberry tongue, cracked lips)

    Extremity changes (desquamation, oedema, erythema)

    Cervical lymphadenopathy (>1.5 cm)

•    Complication: coronary artery aneurysms

•    Investigations:

o    FBC: leukocytosis, thrombocytosis (late), anaemia

o    CRP/ESR: raised

o    Echocardiogram: screen for coronary artery involvement (at diagnosis, 2 and 6 weeks)

•    Management:

o    IV immunoglobulin (IVIG): within 10 days of illness onset

o    High-dose aspirin (anti-inflammatory dose → low-dose for antiplatelet effect)

o    Cardiology follow-up essential