NBME 21 Membranous glomerulonephritis (NBME Answers)

NBME 21 Answers

nbme21/Block 3/Question#34 (reveal difficulty score)
A 39-year-old woman with rheumatoid arthritis ...
Membranous glomerulonephritis 🔍 / 📺 / 🌳 / 📖
tags:

+9 upvote downvote
submitted by ∗mcl(670)

get full access to all content ⋅ pick a username

Membranous glomerulopephritis (aka membranous nephropathy, p 584 FA 2019) may occur secondary to drugs such as penicillamine. Immunofluorescence shows granular deposits due to immune complex deposition. Will also see diffuse capillary and GBM thickening, and SEM will show spike and dome appearance due to subepithelial deposits.

get full access to all content ⋅ pick a username

+6 upvote downvote
submitted by deannosancuck(6)

get full access to all content ⋅ pick a username

Membranous Glomerulonephritis is Nephrotic; ONLY PROTEINURIA is in the vignette

It can't be MPGN because MPGN is Nephritic with possible Nephrotic

Other choices are eliminated by Renal Biopsy

get full access to all content ⋅ pick a username

hungrybox agreed "granular deposits" rules out MCD (the only other nephrotic syndrome) because MCD is IF (-) +4

cooldudeboy1 could someone explain why the other choices are ruled out by biopsy? +

arlenieeweenie @cooldudeboy1 PSGN does have a granular immunofluorescence, but there is no previous illness or hematuria mentioned so you can rule that out. Goodpasture is classically linear IF since they're antibodies against the GBM. IgA nephropathy is mesangial IF so it would deposit more in the middle. Minimal change wouldn't show anything on IF +3

qball I know First Aid states MPGN as a nephritic disease but I think it can present as nephritic or nephrotic syndrome. https://emedicine.medscape.com/article/240056-clinical. Of course, the renal biopsy helps give it away but I wouldn't be so quick as to rule out MPGN +1

taediggity Totally agree w/ you Qball... I thought MPGN too, but I think Penicillamine makes it Membranous Nephropathy +

+2 upvote downvote
submitted by stefanmil(2)

get full access to all content ⋅ pick a username

Why we have deposits in the glomerular membrane. It supposed to be subepithelial - spike and dome - granulations, right?

get full access to all content ⋅ pick a username

lovebug @stefanmil Yap. you're right. I think "Spike and dome" @ EM. and Diffuse capillary and GBM thickening in @ LM. +1

-1 upvote downvote
submitted by ∗sahusema(174)

get full access to all content ⋅ pick a username

It sounds a lot like PSGN, but PSGN is nephritic and we would see pronounced hematuria with minimal proteinuria.

get full access to all content ⋅ pick a username

Must-See Comments from nbme21

nosancuck on Absorption atelectasis
assoplasty on Free T4
seagull on GM2
lnsetick on Apocrine
niboonsh on NMDA receptors are blocked by Mg2+ at the ...
drdoom on Deletion of a hydrophobic amino acid ...
hayayah on HCO3− transported in the plasma
mcl on Aortic
notadoctor on Usual interstitial pneumonitis
madojo on Genital herpes
hungrybox on Obstruction of the bile duct
jambo2222 on Lung
hungrybox on Mismatch repair
hungrybox on Hydrochlorothiazide