Mehl. Peds MSK arthritides/joint (Lupus, reactive, toxic synovitis) 04-08 (1)

Question 1

Lupus. Can present in Peds. Shows up on the forms.

Answer 1

.

Question 2

Lupus. …..most common presenting feature of lupus (90%).???

Answer 2

Arthritis.

USMLE vignette will pretty much always give arthritis in lupus Qs.

Question 3

Lupus.
………….antibodies go up with acute flares and are most closely related to renal prognosis for lupus nephritis.

Answer 3

Anti-double-stranded-DNA (dsDNA)

Question 4

Lupus. antibodies are most specific for SLE (more than dsDNA).???

Answer 4

Anti-Smith (ribonucleoprotein)

Question 5

Lupus.

Anti-phospholipid syndrome due to lupus anticoagulant (antibodies against b2- microglobulin or cardiolipin in patient with SLE).

Answer 5

.

Question 6

Lupus. HY

Anti-phospholipid syndrome can cause false-positive????

Answer 6

Anti-phospholipid syndrome can cause false-positive syphilis VDRL test (HY).

Question 7

Lupus. Malar rash is what HS?

Answer 7

type III hypersensitivity.

Question 8

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.”

Answer 8

.

Question 9

Lupus. hematologic finding?

Answer 9

thrombocytopenia

also antibodies can target other lines, ie WBC and RBC (primena aplastic anemia)

Question 10

!!!!!!!!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.

Answer 10

.

Question 11

Lupus. Similar to RA, lupus can cause cardio what?

Answer 11

pericarditis.

Question 12

Lupus. Flares cause decreased what hematologic?

Answer 12

Flares cause decreased serum complement protein C3.

Question 13

Lupus.

Congenital complement protein C1q deficiency causes ­ risk of developing SLE; sounds nitpicky but it’s on new Step 1 NBME exam.

Answer 13

.

Question 14

Lupus nephritis. First step Mx?

Answer 14

For lupus nephritis, biopsy as the first step in management; steroids first is wrong answer; biopsy first sounds wrong but it guides management.

Question 15

Lupus.

Lupus nephritis = what type?

Answer 15

diffuse proliferative glomerulonephritis (DPGN) on USMLE.

Question 16

Lupus. Treat flares of lupus with ???

Answer 16

steroids.

USMLE doesn’t care about other Txs.

Question 17

Toxic synovitis. Aka?

Answer 17

Aka transient synovitis. 2CK pediatrics forms are obsessed with this.

Question 18

Toxic synovitis. CP?

Answer 18

Presents as hip inflammation/pain in child after a viral infection.

Question 19

Presents as hip inflammation/pain in child after a viral infection. Dx?

Answer 19

Toxic synovitis.

Question 20

Toxic synovitis is diagnosis of exclusion, meaning the vignette gives you various findings that make septic arthritis less likely.

Answer 20

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.

Question 21

Toxic synovitis. Tx?

Answer 21

Treatment is NSAIDs (ibuprofen)àasked on 2CK Peds.

Question 22

Reactive arthritis. CP?

Answer 22

Classically presents as triad of 1) urethritis or abdominal infection, 2) polyarthritis, and 3) “eye-itis” (i.e., conjunctivitis, episcleritis, or anterior uveitis).

Question 23

Reactive arthritis. MO?

Answer 23

Chlamydia is the classic organism that causes reactive arthritis.

!!!Gonococcus does not cause reactive arthritis on USMLE.

Question 24

Reactive arthritis.

Rubella, Hep B+C, and Yersinia can also cause reactive arthritis.

Question 25

Reactive arthritis. Part of HLA-B27 constellation (PAIR), as mentioned above.

Answer 25

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Question 26

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.

Answer 26

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.

Question 27

Septic. Staph aureus is most common pathogen overall.

Answer 27

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.

Question 28

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).

Answer 28

- Treatment is surgical drainage of the joint + antibiotics. USMLE doesn’t care about the exact antibiotics.