Case 43: Pathology

Case 43 Index

Excellent work, your patient tolerated the kidney biopsy well. You review the initial light microscopy with the pathologist.  Click here for a pathology 101 refresher.

MPGN Pattern in C3 Glomerulonephritis on PAS

So, what’s the stain here?
Jones Methamine Silver stain
Look for black staining of the basement membrane for this stain. Try again!
Periodic-Acid Schiff (PAS) stain
Nice! Under the PAS stain, the basement membranes should appear a magenta-ish color.
Hematoxylin & Eosin (H&E) stain
We shouldn’t see black staining of the basement membrane with the H&E stain.
Masson’s Trichrome stain
This stain is used to look for fibrosis, but that’s not what we see here. Think blues and reds for this stain. Pick again!
Which of the following do you see above? (more than one may be correct)
Normal glomerulus
Take another look at the capillary loops, basement membrane, and mesangial space.
Thickened glomerular basement membrane (GBM)
Collapsing glomerulus
This glomerulus is definitely abnormal, but we don’t see collapse of the capillary loops.
Endocapillary proliferation & lobulation of the glomerulus
Yes! Which this disease pattern, there is also often associated increased glomerular size (i.e. glomerulomegaly). Take a look at the labeled image below.
Mesangial expansion
Correct! Take a look at this labeled image below.
Podocyte effacement
The podocyte structures are best visualized under electron microscopy, not light microscopy. Try again!
Double contours of the glomerular basement membrane (GBM)
Yes! We see splitting of the GBM or double contours here.
Your pathologist shows you the electron microscopy (EM). What do you see here (more than one may be correct)?
Podocyte microvillous transformation
Correct! What is seen below are cytoplasmic extrusions of the podocytes, that may indicate podocyte stress.

Tubuloreticular inclusion
Tubuloreticular inclusion (TRI) in an endothelial cell, commonly found in autoimmune diseases and viral infections. We don’t see them here.
Subepithelial deposits
Close…pick again!
Subendothelial deposits
Correct! We see deposits closer to the endothelial side of the basement membrane.

Click here for some more pathology slides…

Case 43 Index
Case 43 Introduction
Case 43 Physical Exam
Case 43 Diagnostic Testing