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Juvenile Idiopathic Arthritis
- collection of diseases
- joint lining inflamed
Epidemiology
- Incidence 1:10000 children
- Prevalence 1:1000
Aetiology
- ?Undetected infection
- salmonella
- Yersinina enterocolitica
- campylobacter
- Borrelia burgdorferi
- mycoplasma
- ?autoimmune
- 90% rheumatoid factor negative
Pathology
- synovium inflamed
- infiltration of lympohcytes and plasma cells
- extension into joint as villi
- excess synovial fluid → effusion
Clinical Features
- polyarticular (>4 joints)
- worse prognosis if rheumatoid factor positive
- often symmetrical
- stiff and swollen joints
- often no pain
- pauciarticular (<4 joints)
- confined to <= 4 (large) joints over 6 months
- Type I
- commoner in girls
- associated with iridocyclitis
- Type II
- commoner in boys
- associated with ankylosing spondylitis / HLA-B27
- systemic
- high fever (>40ºC
- neutrophilia
- hepatosplenomegaly
- lymphadenopathy
- pleuropericarditis
- rash
- appears during febrile periods
- rapidly fades
- multiple small pink macules on trunk and proximal extremities
- arthritis
- often not constant during early stages
Investigations
- ↑ ESR/CRP
- FBC
- ↑ any/all immunoglobulin classes
- ANA
- Rheumatoid factor
- present in 5% and indicates poor prognosis
- X-ray
Differential Diagnosis
Monoarthritis
Management
- Systemic
- aspirin
- blood level 200-300mg/l
- intoxication if tachypnoea
- withdraw during chickenpox / influenza as risk of Reye
syndrome
- avoid steroids unless uncontrolled as hasten bone and joint
destruction
- Polyarticular / Pauciarticular
- Iridocyclitis
- topical steroids
- mydriatics
- Physical Therapy
- General
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