Case 48: Pathology

Case 48 Index

After discussion with your pulmonary colleagues, your decide that a kidney biopsy would help guide management here. You review the initial light microscopy with the pathologist. Click here for a pathology 101 refresher.


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
Under the PAS stain, the basement membranes should appear a magenta-ish color. Pick again!
Hematoxylin & Eosin (H&E) stain
Nice! Here, we don’t see an outline of the tubular basement membrane so this is likely an 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 and try again!
Interstitial inflammation
Collapsing glomerulus
This glomerulus is definitely abnormal, but we don’t see collapse of the capillary loops.
Endocapillary proliferation & lobulation of the glomerulus
We don’t actually see an glomeruli here. Try again!
Mesangial expansion
No glomeruli here! Pick again.
Podocyte effacement
The podocyte structures are best visualized under electron microscopy, not light microscopy. Try again!
With our new data, what’s your most likely diagnosis now?
Volume depletion
Acute tubular necrosis
Diabetic nephropathy
Crystal nephropathy due to valganciclovir 
Acute interstitial nephritis
Infection-related glomerulonephritis
Membranous nephropathy
Thin membrane disease
Autosomal dominant polycystic kidney disease (ADPKD)
Urinary tract infection (UTI)
Myeloma cast nephropathy
A few more tests have been suggested by the pathologist to clinch this diagnosis…take a look at the results below
Angiotensin converting enzyme (ACE) level
It’s high… ( > 80U/L).
Interferon-gamma Release Assay (IGRA) for Mycobacterium tuberculosis
Great! This test is negative.

Ready to wrap things up? Click to move on!

Case 48 Index

Case 48 Introduction
Case 48 Physical Exam
Case 48 Diagnostic Testing