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CNSLF Bone Path 3 - Joint disease/Arthritis (ii) RA (Extra-articular…
CNSLF Bone Path 3 - Joint disease/Arthritis (ii) RA
Intro
AI systemic disorders, affects many organs esp joints, skin, heart, lungs, eyes, LNs + BM
Affects 3% of women + 1% of men
most cases arise in young or middle-aged females
course unpredictable: insidious or remittent
symmetrical
polyarticular
Dx criteria = 4 or more of the following...
morning stiffness which improves with activity
arthritis of 3+ joints
arthritis of hands
symmetrical arthritis
rheumatoid nodule
serum rheumatoid factor
characteristic x-ray findings
pathogenesis
genetic susceptibility
a/w HLA-DR4
30% concordance between monozygotic twins
microbial agent
not fully sure
parvovirus
mycobacteria
mycoplasma
EBV
has been detected in synovium of some patients
has similar epitope to type 2 collagen
AI reaction
type IV hypersensitivity (CD4 T cells)
autoabs (B-cells)
CKs (IL1+TNF) cause injury
Rheumatoid factor
in 80% of patients with RA
IgM (pentameter) ab against FC portion of IgG
titre correlates with severity of disease
RF-IgG immune complexes in synovial fluid + synovial membrane, circulating immune complexes cause extra-articular manifestations (ICD can cause problems anywhere, e.g. GN, vasculitis)
present in <5% of normal elderly
Classically affects synovium of small joints of hands, esp...
proximal interphalangeal joints
swan neck deformity
boutonniere deformity
ulnar deviation of fingers
metacarpophalangeal
radial deviation of wrist
Secondary changes
osteoporosis due to lack of use
osteoarthritis
muscle wasting / atrophy
Pathologic features
synovial hyperplasia
lymphocytes + plasma cells with lymphoid follicle formation + occasional polymorphs in synovium
fibrin
pannus formation
organised inflamm graduation tissue (blood vessels, fibroblasts + myofibroblasts) within synovium which cam erode the articular cart
like a cloth
subchondral cyst formation
juxta-articular erosion @ the joint margin
fibrous ankyloses
Extra-articular manifestations
rheumatoid lung: pul fibrosis + pul nodules (granulomas)
uveitis + scleritis
vasculitis
amyloidosis (AA amyloid)
protein = serum amyloid A (SAA)
APP which is normally soluble
plasma conc highest in inflamm
subcut nodules
lymphadenopathy
Sjogren's syndrome - xerostomia, keratoconjunctivitis
Felty's syndrome
a/w severe longstanding RA
splenomegaly, severe leucopenia + anaemia
Lab investigations
normochromic normocytic anaemia
increased ESR
+ve serology
rheumatoid factor
other autoabs e.g. anti-DNA abs in 10-20%
Tx
NSAIDs
steroids
gold
antimetabolites - azathioprine, MTX, cyclosporine
surgery to correct subluxation of cervical spine
new drugs
anti-TNF abs
omega 3 (blocks production of LT B4 + IL1)