Fogo, Ch. 15 - Acute tubular necrosis

Question 1

What are the two patterns seen in acute tubular necrosis? How can they be distinguished?

Answer 1

Ischemic & toxic

Ischemic is usually more patchy and subtle

Question 2

What are some causes of ischemic ATN?

Answer 2

Rhabdomyolysis, transfusion reactions, shock, hemolysis, and pancreatitis.

Question 3

What are the glomerular LM findings in ischemic-pattern ATN?

Answer 3

Glomeruli are usually unaffected, but may have tubular metaplasia as part of regeneration.

Question 4

What are the tubular LM findings in ischemic-pattern ATN?

Answer 4

“Distalization” of proximal tubule, loss of brush border, patchy loss of tubular cells and some oxalate crystals. Casts (THP or heme/granular).

Question 5

What are the interstitial LM findings in ATN?

Answer 5

Edema, inflammation, granulomata. Most inflammatory cells will be in the vasa recta.

Question 6

What are the EM findings in ischemic-pattern ATN?

Answer 6

Loss of brush border, widespread apoptosis & necrosis.

Question 7

Describe the pathophysiology of ischemic-pattern ATN.

Answer 7

Endothelial injury results in disruption of downstream blood flow and altered permeability. Probably, loss of juxtaglomerular feedback worsens injury.

Question 8

Describe the classic pattern of toxic-type ATN.

Answer 8

Extensive proximal necrosis affecting all nephrons (look to eg Mercuric chloride)

Question 9

Describe the evolution of LM findings in toxic-pattern ATN.

Answer 9

Day 3: Extensive proximal necrosis.

Day 8: No proximal contents. BM remains intact.

Day 14: Cuboidal re-epithelialization.

Question 10

What unique findings can be seen in ATN caused by:

Gentamicin?

Lead?

Gold?

Answer 10

Gentamicin: Myeloid bodies

Lead: Intranuclear inclusions

Gold: Aureosomes