B3.023 Rheumatoid Arthritis Flashcards
non inflammatory arthritis
osteoarthritis
types of inflammatory arthritis
rheumatoid
psoriatic
Crohn’s
definition of osteoarthritis
mechanical derangement of joint
“wear and tear”
cause of primary osteoarthritis
aging
causes of secondary osteoarthritis
trauma
genetic conditions
most common places of osteoarthritis involvement
knee
hip
hands (PIPs, DIPs, MCPs)
rheumatoid arthritis epidemiology
prevalence approx. 1%
-lower in Africa, higher in native americans
women 2-3x more likely than men
peak onset 50-75
describe the clinical presentation of RA
symmetric polyarticular involvement
upper and lower extremities
can affect most joints but spares DIPs
most common joints involved first include MCPs, PIPs, wrists, and MTPs
distinguish between morning stiffness associated with RA and OA
RA usually > 1 hour
OA 30 min or less
how do swollen joints feel early in RA?
fluid filled and boggy
what are some classic joint changes associated with late stages of RA?
ulnar deviation at MCPs in setting of subluxation Z deformity swan neck (extension of PIP and flexion of DIP) boutonniere deformity (flexion of PIP and extension of DIP)
what are some clues to distinguish OA?
associated with activity short morning stiffness DIPs affected bony appearing changes no ulnar deviation
which type of arthritis is associated with extraarticular manifestations
RA is a systemic inflammatory disease not limited to just the joints
pulmonary extraarticular manifestation
pleural disease (effusions and pleurisy) pulmonary nodules interstitial lung disease (extensive honeycombing on CT due to scarring and destruction)
cardiac extraarticular manifestation
pericarditis and pericardial effusion (similar to lupus)
nodules (can affect conduction and valves)
myocarditis
accelerated CAD
skin extraarticular manifestations
rheumatoid nodule rheumatoid vasculitis (inflammation of blood vessels leads to occlusion and ischemia)
eye extraarticular manifestations
secondary Sjogren’s/Keratoconjunctivits sicca (inflammation of salivary glands, dryness of eyes and mouth)
episcleritis and scleritis
corneal melt
hematological extraarticular manifestations
Felty’s syndrome - splenomegaly, leukopenia, and RA
what are some nonspecific changes the body may undergo related to inflammation in RA?
anemia of chronic disease
thrombocytosis
leukocytosis
neurologic extraarticular manifestations
entrapment neuropathy (carpal tunnel syndrome, due to swelling) spinal cord compression related to spine involvement such as C1-C2 (can lead to paralysis)
discuss the genetic findings of twin studies related to RA
monozygotic: 15-30%
dizygotic: 5%
general population: 1%
what is the shared epitope of RA?
highly similar AA sequence in alleles in HLA-DRB1 locus
strongest genetic link to RA
what is HLA-DRB1 involved in?
MHC molecule-based antigen presentation
self peptide selection
T-cell repertoire
what are some environmental factors that may contribute to RA?
silica (caplan’s syndrome)
smoking
periodontal disease
gut microbiome
which type of Th cell is an important link with the innate immune system?
Th17
how are autoantibodies related to the innate immune system?
can activate macrophages
which type of leukocyte activate downstream cells that mediate damage seen clinically in RA?
macrophages
how does RA appear on an H&E stain?
fibrovascular tissue protrudes from inflamed synovium into the articular cartilage
what is the roles of osteoclasts in RA?
ultimately lead to bone destruction resulting in erosions and joint deformities
which lab tests assist with diagnosis of RA?
rheumatoid factor (RF)
anti-cyclic citrullinated peptide (CCP)
anti-nuclear antibody (ANA)
which lab tests assist with monitoring RA disease activity?
erythrocyte sedimentation rate (ESR)
c-reactive protein (CRP)
which lab tests assist with medication monitoring in RA?
CBC with dif
creatinine
AST, ALT
rheumatoid factor
autoantibodies that recognize determinants of the Fc portion of IgG
most commonly IgM against Fc portion of IgG
sens: 70-80%
spec: 70% (increases w age and associated with other diseases)
anti-cyclic citrullinated peptide (CCP)
post translational modification to arginine performed by antibody peptidylarginine deiminase (PAD) to form citrulline
sense: 70%
spec: 95%
why is citrullination an issue?
citrullinated proteins fit with the HLA-DRB1 epitope on APCs, stimulating antibody production
if you then get citrullinated proteins in your joints, they complex with the Abs stimulating complement activation/ an inflammatory response
how is smoking thought to be related to RA?
smoking promotes PAD enzymes and citrullination in the lungs
what is seronegative RA?
people with RA who test negative for both RF and CCP
20% of patients
seropositive RA
associated with worse prognosis
what about positive RF and CCP but no RA?
patients could be early in disease development or may not develop disease at all
synovial fluid findings in RA
inflammatory synovial fluid cell count
5000-50000 cells w predomninant neutrophils
radiographic findings in RA
periarticular osteopenia (bones near joints get darkers) symmetric joint space loss marginal erosions soft tissue swelling no new bone formation
is MRI commonly used to diagnose RA?
no, not usually worth additional cost to see minimally different images
ultrasound findings of RA
high power Doppler signal consistent with active disease
gray scale synovial hypertrophy
when do you use ultrasound in RA patients?
prognosis more than for diagnosis
radiographic findings in RA versus OA
RA: erosions, periostitis, joint space narrowing
OA: joint space narrowing, osteophytes, subchondral sclerosis
