is there inflammation?
If NO, think: OA, torn meniscus or some structural prob, osteonecrosis, tumor.
If YES: How many joints are involved?
1: Lyme dz, indolent infx, crystal-induced
few (oligo): indolent infx, crystal-induced, spondyloarthritis, Still's dz.
poly: RA/psoriatic, connective tissue dz (SLE), vasculitis, myositis, crystal-induced, still's dz.
Normal joint fluid: clear, <200 WBCs, <25% PMNs, - cx
Noninflamm: clear, yellow; <2K WBCs, <25% PMNs, -cx
Inflamm: clear-opaque yellow/white; > 2K WBCs, >50% PMN, -cx
Septic: opaque, >2K (>50K), >75% PMNs, + cx
variable onset, definite inflammation of enthesitis (where tendons/ligaments insert into bones).
oligo/polyarticular of SI joint, spine, large peripheral joints. ANY joint can be involved.
PE: dactylitis, enthesitis (Achilles), bamboo spine, syndesmophytes. May be assoc'd w/ psoriasis, IBD, uveitis.
lab: +/- HLA-B27. Radio: pseudo-widening of joint space (early); sclerosis, erosions, ankylosis. MRI most sensitive for early change in SI joint. for peripheral enthesitis, US~MRI.
Skin: rheumatoid nodules on the extensor surfaces, bursae, lung/heart/sclera.
(20%) Pulm: ILD, pleuritis, effusions (low glc), nodules, airway disease, PHT
CV: pericarditis, effusions, myocarditis, accelerated atherosclerosis, AF, coronary/systemic vasculitis, increased CV death.
neuro: mono/polyneuritis multiplex, CNS vasculitis, stroke, nerve entrapment.
Eye: scleritis, episcleritis, keratoconjunctivitis sicca (2o sjogren's)
heme: anemia of chronic disease, neutropenia, felty's sx, NHL, amyloidosis
renal: glomerulonephritis, nephrotic syndrome, renal damage 2/2 NSAIDs, MTX
vasculitis. (small & medium vessels.
elevated ESR/CRP, leukocytosis, eosinophilia, anemia of chronic inflammation.
Screen for pulm and cardiac involvement (PFTs, CXR/CT, bronch, ECG, TTE).
On bx, might find deposition of proteoglycan, perichondral inflammation, replacement w/ granulation tissue + fibrosis, Ig/C3 deposits w/ immunofluorescence.