Mehl. Peds MSK arthritides/joint (Lupus, reactive, toxic synovitis) 04-08 (1) Flashcards
Lupus. Can present in Peds. Shows up on the forms.
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Lupus. …..most common presenting feature of lupus (90%).???
Arthritis.
USMLE vignette will pretty much always give arthritis in lupus Qs.
Lupus.
………….antibodies go up with acute flares and are most closely related to renal prognosis for lupus nephritis.
Anti-double-stranded-DNA (dsDNA)
Lupus. antibodies are most specific for SLE (more than dsDNA).???
Anti-Smith (ribonucleoprotein)
Lupus.
Anti-phospholipid syndrome due to lupus anticoagulant (antibodies against b2- microglobulin or cardiolipin in patient with SLE).
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Lupus. HY
Anti-phospholipid syndrome can cause false-positive????
Anti-phospholipid syndrome can cause false-positive syphilis VDRL test (HY).
Lupus. Malar rash is what HS?
type III hypersensitivity.
Lupus.
Malar rash is type III hypersensitivity. Harder Qs won’t mention this finding because it’s too buzzy. You need to know thrombocytopenia is frequently seen in lupus due to anti-hematologic cell line antibodies. Antibodies can also target WBC and RBCàlooks like aplastic anemia, but it’s notàanswer = “increased peripheral destruction,” not “decreased bone marrow production.”
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Lupus. hematologic finding?
thrombocytopenia
also antibodies can target other lines, ie WBC and RBC (primena aplastic anemia)
!!!!!!!!Lupus. PIRMA KARTA GIRDZIU.
Can cause lupus cerebritis (confusion / delirium-like episodes) and transverse myelitis (presents as Brown-Sequard syndrome). Peds form gives lupus cerebritis.
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Lupus. Similar to RA, lupus can cause cardio what?
pericarditis.
Lupus. Flares cause decreased what hematologic?
Flares cause decreased serum complement protein C3.
Lupus.
Congenital complement protein C1q deficiency causes risk of developing SLE; sounds nitpicky but it’s on new Step 1 NBME exam.
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Lupus nephritis. First step Mx?
For lupus nephritis, biopsy as the first step in management; steroids first is wrong answer; biopsy first sounds wrong but it guides management.
Lupus.
Lupus nephritis = what type?
diffuse proliferative glomerulonephritis (DPGN) on USMLE.
Lupus. Treat flares of lupus with ???
steroids.
USMLE doesn’t care about other Txs.
Toxic synovitis. Aka?
Aka transient synovitis. 2CK pediatrics forms are obsessed with this.
Toxic synovitis. CP?
Presents as hip inflammation/pain in child after a viral infection.
Presents as hip inflammation/pain in child after a viral infection. Dx?
Toxic synovitis.
Toxic synovitis is diagnosis of exclusion, meaning the vignette gives you various findings that make septic arthritis less likely.
Leukocytosis and inability to bear weight make septic arthritis the likely answer over toxic synovitis. Hard questions will not mention warmth or redness as ways to differentiate. Fever can present in both.
Toxic synovitis. Tx?
Treatment is NSAIDs (ibuprofen)àasked on 2CK Peds.
Reactive arthritis. CP?
Classically presents as triad of 1) urethritis or abdominal infection, 2) polyarthritis, and 3) “eye-itis” (i.e., conjunctivitis, episcleritis, or anterior uveitis).
Reactive arthritis. MO?
Chlamydia is the classic organism that causes reactive arthritis.
!!!Gonococcus does not cause reactive arthritis on USMLE.
Reactive arthritis.
Rubella, Hep B+C, and Yersinia can also cause reactive arthritis.
Reactive arthritis.
Part of HLA-B27 constellation (PAIR), as mentioned above.
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Septic. Shows up on Peds forms as young healthy patient with recent trauma (e.g., car accident) or high-intensity exercise causing microtrauma (e.g., kickboxing/soccer tournament, long hike), as well as in sickle cell disease.
- USMLE will give hot, red, painful joint in one of the above patient groups, almost always with a fever.
First step in management is arthrocentesis. A high-yield point is that joint aspirate can be negative for organisms. Do not rule-out SA if NBME says no organisms.
Septic.
Staph aureus is most common pathogen overall.
Choose Salmonella in sickle cell. But you have to use your head. Salmonella is a gram-negative rod, so if they say gram-positive cocci is cultured in sickle cell, the answer is still staph aureus.
Septic.
Gonococcus is the answer for sexually active patients; presents two ways on USMLE: 1) monoarthritis of the knee in sexually active young patient, with no other information provided; or 2) as a triad: mono- or polyarthritis, cutaneous papules, and tenosynovitis (inflammation of tendon sheaths).
- Treatment is surgical drainage of the joint + antibiotics. USMLE doesn’t care about the exact antibiotics.
