4 - Juvenile Idiopathic Arthritis Flashcards
What is the second most common chronic disease in childhood?
Juvenile Idiopathic Arthritis (second only to asthma)
Arthritis
Requires one of the below: Joint swelling or effusion Limited range of motion of the joint Heat over the joint Redness over the joint
Pain in the joint is not sufficient to call it arthritic. Without the others, it is arthralgia.
Juvenile Idiopathic Arthritis - Criteria
Less than 16 years old at the onset
Persistent arthritis in one or more joint for more than 6 weeks
Exclude other forms of arthritis
JIA is distinct and a different disease from RA
Classifications of Juvenile Idiopathic Arthritis
Systemic JIA (10 - 20%) - has fever and rash, sometimes no arthritis Pauci-articular (40 - 60%) - fewer than 5 joints involved Polyarthritis RF (-) (20 - 25%) - More than 5 joints Polyarthritis RF (+) (5 - 10%) - More than 5 joints, probably have adult RA, but are below the cutoff for age Enthesitis-related arthritis (10 - 15%) - insertion of tendon or ligament into the bone, arthritis at the insertion site Psoriatic arthritis (5%) Undifferentiated (5%)
Lumped together in peds, but really they respond to different treatments, and they are DIFFERENT DISEASES gurl
Juvenile Idiopathic Arthritis - Etiology
Unknown and multifactorial
Activated T cells and macrophages are involved in pathogenesis
In some types, autoantibodies are elevated such as ANA and RF
Elevated levels of cytokines are present such as IL-1, IL-6 & TNF-α
ANA positivity
Some JIAs are ANA positive
Rheumatoid Arthritis typically is not.
JIA - Innate immune system
Uncontrolled activation of PMN is present in poly-articular disease
Genetic polymorphisms of the IL-1 B genes are associated with susceptibility to systemic JIA
Increased NK cells are present in systemic JIA
JIA - Adaptive immune system
Polyclonal B-Cell activation is reflected in the hypergammaglobulinemia present in JIA
Complement is activated and associated with activity of the disease
Activated T cells are increased in the pauci and poly-articular disease
CD4+ T cells are the predominant infiltrating cell in the inflamed synovium
JIA - Presentation
Insidious onset
Minimal pain
Morning stiffness and walk with a limp, sometimes have to have their parents carry them around for half an hour in the morning
Change in function and in activity level
Knee is the most common joint involved
PIP joint involved in psoriatic arthritis
Pauci-articular JIA
Fewer than 5 joints Peak incidence at 2 years old Female/male 5:1 No systemic disease Associated with uveitis ANA positivity 80%
Polyarthritis (JIA)
Over 5 joints involved Peak at 2 years old Female/male 3:1 Often unremitting 10% RF positive, 40% ANA positive Guarded prognosis - more severe, tends to become chronic
Systemic JIA
Variable number of joints involved, or no joints at all
Any age, throughout childhood (can spill into adulthood)
Female/male 1:1
50% unremitting and destructive
Very rare autoantibodies or uveitis
Now known to be auto-inflammatory and dependent on EITHER IL-1 or IL-6, not both. Auto-inflammatory, not autoimmune, because it’s due to one specific cytokine.
Salmon fleeting rash (mild red, not itchy, transient at the height of the fever, usually central)
JIA - Differential of Excluded Diseases
Mechanical traumatic (Patello-femoral syndrome, SCFE, Osgood-Schlatters) Infectious (Lyme) Hematologic or oncologic Other rheumatologic diseases Inflammatory conditions (FMF, IBD) Chronic pain syndromes
Specific to childhood arthritis
Delayed growth, particularly height
Delayed puberty
Localized growth disturbances from accelerated growth
Significant TMJ involvement
Localized growth failure (eg second digit)
If a kid has ANA positive JIA
Send them to the ophthalmologist every 3 months if you don’t want them to go damn blind.
