04: Juvenile Idiopathic Arthritis Flashcards
What are the diagnostic criteria for JIA?
- Less than 16yo at onset
- Persistent arthritis in 1+ joints for more than 6wks
- Exclude other forms of arthritis
What are the different classifications of JIA?
- Systemic (10-20%)
- Pauci-articular (40-60%)
- Polyarthritis RF - (20-25%)
- Polyarthritis RF + (5-10%)
- Enthesitis-related arthritis (10-15%)
- Psoriatic arthritis (5%)
- Undifferentiated (5%)
JIA etiology
- Unknown and multifactorial
- Activated T cells and macrophages
- AAbs elevated (ANA, RF)
- Cytokines elevated (TNF-a, IL-1, IL-6)
Role of innate immunity in JIA
- Uncontrolled activation of PMN in polyarticular dz
- Genetic polymorphisms of IL-1 B genes associated w/ systemic dz
- ↑NK cells in systemic dz
Role of adaptive immunity in JIA
- Polyclonal B-cell activation in hypergammaglobulinemia
- Complement activated
- ↑activated T cells in pauci and polyarticular dz
- CD4+ T cells predominant infiltrating cell in inflammed synovium
Presentation of JIA
- Insidious onset
- Minimal pain
- Morning stiffness and limp
- Change in function and activity level
Pauciarticular onset JRA
- Fewer than five joints (finger PIP joints - no matter how many involved - count as one joint)
- Peak incidence = 2yo
- F:M 5:1
- No systemic dz
- Associated w/ uveitis
- ANA positive 80%
Polyarticular onset JRA
- Five or more joints involved
- Peak = 2yo
- F:M 3:1
- Often unremitting
- 10% RF +; 40% ANA +
Systemic onset JRA (Still’s Dz)
- Arthritis of any number of joints
- Any age throughout childhood
- F:M 1:1
- 50% unremitting and destructive
- Very rare AAbs or uveitis
- Auto-inflammatory and dependent on IL-1, IL-6
- P/w salmon fleeting rash
What do these images show?
- Salmon fleeting rash
- Occurs with fever, which may occur 2x/day
What is on the ddx with JIA?
- Mechanical or traumatic
- Infectious (Lyme)
- Hematologic or oncologic
- Bone > joint pain
- Other rheum dz
- Inflammatory conditions (FMF, IBD)
- Chronic amplified pain syndrome
Problems specific to childhood arthritis
- Delayed growth (height)
- Delayed puberty
- Localized growth disturbances from accelerated growth (e.g., unequal leg length)
- Significant TMJ involvement
What is uveitis and what is its association with JIA?
Swelling and irritation of the uvea, the middle layer of the eye; provides most of the blood supply to the retina.
Occurs with pauci-articular JIA; often initially silent; by the time the child complains of pain in the eye or difficulty seeing, it is likely that permanent and irreversible damage has already occurred.
If pt has pauci-articular JIA or +ANA, must see eye doctor more frequently.
What lab tests aid in the dx of JIA?
- CBC (anemia, thrombocytosis)
- APRs (in systemic dz)
- Once dx made, check:
- ANA
- RF
- HLAB27
- R/o septic arthritis via synovial fluid
What is the purpose of finger splinting?
Avoids contractures
