Definition
JRA / JCA
- heterogenous inflammatory joint disease
- °infective aetiology
- > 3/12 duration & < 16 years old
Systemic / Pauciarticular / Polyarticular
Epidemiology
1: 10000
- M = F
- Different subgroups have associated with different HLA types
Aetiology
Unknown
- ? Immune aberration to infectious agent
- Similar to RA
- Genetic predisposition
Classification
Must be > 6/52
Classify after 6/12
1. Systemic JCA
- Still's disease
- fever, rash, lymph nodes, hepatosplenomegaly
- 20%
- poorest long term prognosis
2. Pauciarticular JCA
- < 4 joints
- 30%
Divided into
A. Early onset < 6
- ANA
- F > M
B. Late onset
- like Ankylosing Spondylitis / HLA B27
- M > F
3. Polyarticular JCA >5 joints
- 60%
- most common
Divided into
A. Seronegative
B. Seropositive
- more severe with joint destruction
Systemic / Still's Disease
Epidemiology
Usually < 3 years old
- M = F
- usually not ANA or RF +ve
Systemic symptoms
Febrile ~ 40°
Maculopapular rash
Malaise
Nodes
Hepatosplenomegaly
Joint symptoms occur weeks after onset
Joints
Initially mild swelling & pain
- may progress to Polyarthritis
- commonly Knee / Wrists / Ankle & Midfoot
- flexor Tenosynovitis
- MCPJ & PIPJ swelling
Usually resolves with systemic illness
- long term affects hips and cervical spine
Rash
Fluctuates with the fever
- may only appear at night or in evening
- i.e. not when seen in clinic
- salmon pink
Investigations
ESR ~ 100
Increased WCC + Neutrophilia
Mild Anaemia
Increased IgG
RF negatgive
Increased CD4 T Cells
Prognosis
Children almost always get spontaneous resolution of disease as teenager
- left with degenerative joints
- moderate to severe arthritis in ~ 50%
- frequent involvement of hips
Stunted growth
- steroids make stunting even worse
Pauciarticular
Very typical case presents with monoarticular arthritis of knee
- < 5 joints in 1st 3/12
- no Stills symptoms
A. Early onset / 50 - 60% ANA Positive
Present
- <6 years
- F>M
Medium joints
- Knee / AJ / Elbow
- Flexor Tenosynovitis
- PIPJ
Chronic Iridocyclitis
- 50%
- resolves after few years
- follow up until late teens for eyes
B Late onset / Positive HLA B27
Present
- > 9 years
- M > F
- positive FHx
- RF negative
Most develop Sacroiliitis & Spondylitis
LL affected
- KJ / AJ / Hip
Enthesitis
- Plantar Fascia / TA / Tib Tubercle
Iritis
- commonest cause of blindness in western world
- can be treated with steroids
- must all see ophthalmologist every 3 months until 20 years old even if in remission
Overall excellent prognosis
- minimal drug treatment required
- Main problem is actually the iritis
Polyarticular
Present
- > 5 joints within first 3/12
- F > M
- ANA positive in 50%
- symmetrical polyarthritis
- small & large joints
A. Seronegative
More common
- 85% of polyarticular
Affects KJ most commonly
- wrists / ankle / C spine
- flexor tenosynovitis
- 1st MTPJ
B. Seropositive / Juvenile RA
Older girls
- Small joints of hands & feet
- nodules
- +ve RF
Rapidly progressive with joint destruction
- more likely to be persistent into adulthood
X-ray
- non-specific changes early
- have severe periarticular osteopenia
- later joint erosion & deformity