A 58-year-old man with diabetes mellitus presents to the emergency department with acute kidney injury following a major surgical procedure. Renal biopsy shows acute tubular necrosis (ATN) with loss of brush border, cellular edema, and mitochondrial swelling. Which of the following is NOT a characteristic morphological or functional feature of ATN?
A. Flattening of tubular epithelial cells with loss of brush border
B. Glomerular sclerosis and crescent formation
C. Preservation of the basement membrane of the tubules
D. Cellular necrosis predominantly affecting the proximal convoluted tubule and thick ascending limb of loop of Henle
Explanation
Morphological Features of Acute Tubular Necrosis
Key Point
ATN is characterized by loss of tubular epithelial cell integrity while the basement membrane remains intact — this is the hallmark that distinguishes ATN from more severe glomerular injury.
The preserved basement membrane is why ATN is potentially reversible — epithelial cells can regenerate and re-epithelialize the denuded basement membrane.
Why Glomerular Sclerosis & Crescent Formation Are NOT Features of ATN
Clinical Pearl
Glomerular crescents and sclerosis are hallmarks of:
Rapidly progressive glomerulonephritis (RPGN) — crescentic GN
Chronic glomerular disease — focal segmental glomerulosclerosis (FSGS), membranoproliferative GN
