18. Juvenile Idiopathic Arthritis Flashcards
Juvenile Rheumatoid Arthritis and Juvenile Idiopathic Arthritis? same thing?
Yep. JRA is the old term, JIA is new term.
What are the biggest complaints brought in by school-age children?
- Headaches
2. Musculoskeletal
Kids who have JIA: do they typically present with CC of pain? How do they typically present?
Not with complaints of pain, but rather with limping, stiffness, being slow in the morning, not running around as they typically do. They may not know that something is wrong.
Abnormalities observed in children with MSK problems?
- Weight, height retardation
- Localized growth abnormalties: Limb length and size (one may be longer than the other); micrognathia (undersized jaw), scoliosis
- Delayed secondary sex characteristics
How can muscoloskeletal milestones help you detect MSK issues?
If you know what milestones they have achieved, you’ll be able to detect regression. Regression in MSK abilities may be due to limited motion, contracture of a joint. Child’s response to this is usually to regress to an earlier dev stage.
MSK exam: what do S, T and L stand for?
Swelling
Tenderness
Limited ROM
If see decreased ROM, palpate the joint to investigate. ROM = good screening tool.
Lab tests: what tests do we generally ALWAYS run if we suspect problems?
? Utility of other tests (ESR/CRP, RF, ANA, viral serologies, HLA B27)?
CBC, UA, cultures. Occasionally we will catch a case of leukemia based on this.
Utility of others generally same as for adults – can be helpful, can be misleading. Most tests better for monitoring progress than for diagnosis.
Positive ANA or incr ESR seen 10% of the time in normals.
RF doesn’t tend to be accurate in kids (?- he said “not good”)
ESR/CRP: acute phase reactants, normal 40% of the time in kids with mono or poly-JIA. High in kids with systemic JIA. (again, better for monitoring than dx).
Differential dx of JIA: what are the 4 main categories we should be thinking of?
- Infection (most common JIA-like presentation = post-strep Reactive Arthritis)
- Connective Tissue Diseases (Dermatomyositis, systemic vasculitis most common CT dz’s in kids)
- Mechanical and Ortho problems (Osgood-Schlatter’s dz is common)
- Systemic Diseases (Hemophilia, Endocrine disorders, Lipid Storage, Malignancy)
What is Osgood-Schlatter’s Disease?
Very common in kids. Patellar tendon anatomy: attaches to tibial tubercle. In OS, tendon pulls bone away from tubercle. Example of enthesitis).
What is Benign Juvenile Hypermobility Syndrome? How is it assessed?
BJHS: genetic disease that may present very similar to JIA. Causes hypermobility, common cause of pediatric arthralgia.
Assessed via Beighton Score (0-9, score of 5+ is diagnostic): hyperextension of elbows/knees, touch thumb to forearm, pinky bending back to 90’, palms to floor
JIA: incidence and prevalance?
Definition?
The most common CT disease of childhood.
Incidence = 1/10,000 (which is 10% adult incidence)
Prevalence = 1/1,000 (also 10% adult prev)
Definition: A chronic arthritis (decr ROM, swelling) persisting in 1 or more joint for > 6 wk at age <16yr. Other etiologies excluded (ie Lyme, leukemia).
NOTE: may be only one joint, 6 weeks or more, pt must be <16yo.
JIA: what are the subtypes? How are they classified?
The subtypes are Pauci/Oligo Articular, Poly-Articular, Systemic, with different sx’s depending on whether they present in 0-5, 6-10, or 11-16 yr olds.
Basically, based on the number of joints involved, the presence/absence of systemic or other features, and age of onset.
Classification is made by mode of onset in the first 4-6 months.
JIA: what is the most common clinical presentation? (age, # joints involved?)
He said this a few times!
Most common presentation of JIA is a girl aged 0-5, with fewer than 5 joints involved.
–> YOUNG GIRL, PAUCI or OLIGO-ARTICULAR presentation.
In the most common presentation of JIA (young girl, 0-5, 5 or fewer joints), what is an important test to do? What does it indicate?
Impt to get an ANA.
If positive, –> anterior uveitis is more likely.
With Pauciarticular disease in the 0-3 y age category, are we more likely to see M or F?
What about the 11-16 yo category?
0-5yrs: F >>M
11-16 yrs: M>>F
Of the Pauciarticular presentations of JIA in 11-16 year olds, what symptoms are typically seen?
Lower limb involvement
Enthesitis
Iritis
50% will be HLAB27 positive and progress to ankylosing spondylitis.
What is iritis? what is it associated with?
Acute and painful red-eye.
Associated with ankylosing spondylitis, Crohn’s.
JIA with systemic involvement: how are these dx’s often made?
Often we make these diagnoses when the pt is inpatient, with a Fever of Unknown Origin, negative workup, Bimodal Fevers that present with faint rash, monocytic anemia (anemia of chronic disease).
They may have high ESR and CRP.
ANA, RF, ANCA will be negative.
What is the histology of JIA? What parts of joint are affected, infiltrates are composed of what?
Similar to adult RA: synovial hyperplasia, hypervascularity, infiltrates of lymphocytes and plasma cells.
Features: pannus, erosion and destruction of articular cartilage.
Fibrosis and contracture of periarticular tissues are more common, and bony ankylosis develops quickly.
At the level of the immune response, what is the pathogenesis of synovitis?
What actually causes the joint destruction?
T cells signal to macrophages, releases TNF (key cytokine to this process), also IL6, IL1.
All work together at the synovial membrane to cause thickening of synovium, recruitment of WBCs, hypervascularity, activation of osteoclasts that cause joint destruction.
Photo of polyarticular JIA. What specifically is shown here?
All joints swollen, thickened. Flexion contractures, swelling in the extensor tendons. Slightly less involvement on R side.
What are we seeing here?
Polyarticular JIA
Synovitis in wrist, somewhat cystic, tenosynovitis in hand. All IP joints are involved.
What is this, what category of JIA does it appear with?
Sytemic onset JIA rash.
Usually more faint than these examples, may peak at night with (bimodal) fever. Parents may have to sneak in at night to assess for this rash.
(bimodal fever means that kid will feel fine for 5-6 h, then will feel bad with fever for a few hrs. repeats thru day)
What is this, what is it associated with?
systemic-onset JIA. Rash with Koebner phenomenon and ascites.
May alse see enlarged axillary LN as below.
What is seen here? what complication of JIA does it represent?
Middle MCP is shorter than the others, can see that growth plate is closed.
General trend in JIA is that normal growth may be affected, with epiphyseal overgrowth initially (due to hypervascularity due to inflammation etc) but subsequent premature closure and ultimately, growth retardation.
growth retardation is generally limited to active polyarticular or systemic disease (esp with steroid tx)
What’s seen here?
JIA involvement of the 2nd MTP - swelling on gross, and shortened bone on xray with closed growth plates (I don’t see those but whatever).
If there is C-spine involvement with JIA, what joint does it tend to affect? Might be associated with what?
C-spine may be involved in 60% of JIA.
Tends to affect apophyseal joint of C2,3,4 and cause decreased lateral neck flexion.
May be associated with microganthia.
What is this, what is it associated with?
Micrognathia.
With C-spine involvement, may get mandibular overgrowth due to hypervascularity, and subsequent premature fusion. Basically undergrowth of the jaw.
Yikes, what is this? Associated with what? What can it cause? Treatment?
Anterior uveitis. (in 20% of oligo-articular, ANA+ JIA cases).
Usually asx, if undetected can cause blindness.
Treatment with ocular steroids.
Meds for JIA: what part of the inflammatory process do they target?
- Orencia
- Enbrel
- Humira
- Kinerat
- Tocilzumab
- Orencia: Anti-CTLA4 ligand. Inhibits T cell signalling with macrophage.
- Enbrel: TNF receptor antagonist
- Humira: MAB that targets TNF
- Kinerat: IL1-R antagonist.
- Tocilzumab: IL6-R antagonist. very effective for systemic, polyarticular JIA
