NBME 22 Immune complex-mediated cytotoxicity (NBME Answers)

Retired NBME 22 Answers

nbme22/Block 3/Question#4 (reveal difficulty score)
A 29-year-old woman has an inflammatory ...
Immune complex-mediated cytotoxicity 🔍 / 📺 / 🌳 / 📖
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submitted by ∗welpdedelp(270)

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This was SLE. https://step1.medbullets.com/msk/112039/systemic-lupus-erythematosus

Think: 1,2,3= S-L-E

Using ACID: Type III is for Immune Complexes

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jurrutia What do you mean by ACID? +

skonys @jurrutia A - Type 1 = Allergic/Anaphlaxis C - Type 2 = Cytotoxic (Anti-body) I - Type 3 = Immune-Complex mediated cytotoxicity D - Type 4 = Delayed type (which I dont like because it doesn't actually tell you anything really) +1

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submitted by airhead5(2)

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Does anyone know the disease they are talking about? I was thinking lupus which makes sense with the answer, but i can’t find anything on anterior chamber of eye and choroid plexus.

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liverdietrying It's lupus, all the symptoms listed are classic especially the serositis. Anterior chamber of the eye = uveitis. Choroid plexus = cerebritis. For a great overview, check out this (free) video: https://onlinemeded.org/spa/rheumatology/lupus/acquire +5

in_a_pass_life I think this was reactive arthritis, not lupus. Choroid plexus not just in the brain, also in eye (can’t see, can’t pee, can’t climb a tree). Mechanism of reactive arthritis is immune complex deposition, per UWorld, which was correct answer. +5

trichotillomaniac The inside of the eye is divided into two chambers: the anterior chamber and the posterior chamber. Both chambers contain fluid, and when there’s inflammation in the eye, a specialist can often see inflammatory cells in the fluid. https://www.hss.edu/conditions_eye-problems-lupus.asp +

trichotillomaniac I agree that this is Lupus after doing some more research! +1

nwinkelmann I find this article describing the SLE ocular manifestations, including uveitis and cerebritis. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4908056/ Also this talks about the lupus cerebritis (choroid plexus inflammation): https://en.wikipedia.org/wiki/Cerebritis +

medulla every time I read about Lupus there is something new!! +1

aakb woman of child bearing age + serositis + arthralgias/arthritis >=2 +

aakb kidney issues (main cause of death in sle) +

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submitted by ∗jsmoov(25)

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The main differential here is RA vs SLE. They have many overlapping signs and symptoms (including pleuritis and pericarditis - as well as scleritis), but the key differentiating factor is that RA typically doesn't involve KIDNEY damage.

Lupus, however, is well known for causing DPGN.

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submitted by fallot4logy(11)

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why not sarcoidosis? 1.rheumatoid arthritis like symptoms 2.uveitis 3.kidneys ...only serositis is a bit controversial

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drzed Need some pulmonary symptoms to make sarcoid convincing. I know in real life people can present with primary neurosarcoid or something crazy but on exams, it'll be classic presentation. No granulomas, hilar lympadenopathy, or interstitial lung disease = probably not sarcoid +1

peridot Just curious but if it had been sarcoidosis, would "systemic release of IL-1 and TNF" be an accurate description for the pathogenesis? +

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submitted by fallot4logy(11)

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why not sarcoidosis? 1.rheumatoid arthritis like symptoms 2.uveitis 3.kidneys ...only serositis is a bit controversial

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seracen I usually look for the hilar manifestation, when considering sarcoidosis, or the skin manifestations. Personally, I thought Sjogren's when I read this. +1

peridot @seracen I can see why you thought Sjogren, but I think Sjogren would have more emphasis on dryness of mucus membranes and eyes (technically the question stem does say "anterior chamber of the eye", but Sjogren is more like the surface of the eye so "anterior chamber" is a weird way to put it - usually that refers more to uveitis). Also, choroid plexus (whether that refers to eye or brain... tbh idk about that yet), but either way, doesn't really fit Sjogren. Kidney involvement is also rather rare with that I believe. +1

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