Renal Vascular Pathology

Question 0

3 HTN-related kidney vascular disorders?

Answer 0

“Benign” nephrosclerosis.
Malignant nephrosclerosis.
Collagen problems (e.g. scleroderma)

Question 1

3 main categories of vascular disorders affecting the kidney?

Answer 1

Hypertension.
Decreased renal blood flow.
Thrombotic microangiopathies.

Question 2

Why is “benign” nephrosclerosis called “benign”?

Answer 2

It shouldn’t be. I guess it’s to distinguish it from malignant nephrosclerosis caused by malignant HTN… but benign nephrosclerosis does a lot of damage.

Question 3

What drives “benign” nephrosclerosis?

Answer 3

Longstanding mild to moderate HTN.

Question 4

Gross appearance of kidney with “benign” glomerulosclerosis? (4 specific things)

Answer 4

Coarse, granular cortical surface (they showed one of these on the path cart).
Reduced kidney weight.
Reduced nephron mass.
Mild thinning of cortex.

Question 5

3 microscopic changes seen in “benign” nephrosclerosis?

Answer 5

Hyaline arteriosclerosis.
Patchy interstitial fibrosis and tubular atrophy.
Global glomerulosclerosis.

Question 6

What is the “hyaline” in hyaline arteriosclerosis?

Answer 6

An insudate of plasma proteins that moves into vessel walls -> narrowing of lumen.

Question 7

What does global glomerulosclerosis refer to?

Answer 7

There’s sclerosis of the entirety of each individual affected glomerulus (in contrast to “segmental”).

Question 8

What changes happen to larger vessels (not arterioles) of the kidney in “benign” nephrosclerosis?

Answer 8

Intimal fibrosis and medial thickening -> narrowed lumen.

Question 9

Gross appearance of a kidney with malignant nephrosclerosis?

Answer 9

“Flea bitten” appearance - multiple pinpoint petechial hemorrhages.

Question 10

Major process that you see in histology of malignant nephrosclerosis (that you wouldn’t see in “benign”)?

Answer 10

Necrosis, especially fibrinoid necrosis.

and some other things

Question 11

What is fibrinoid necrosis? What’s the eosinophilic stuff?

how can you distinguish this from hyaline, if you’re confused

Answer 11

Necrosis of small vessels in kidney with fibrin deposition.

the fibrin is rough on RBCs, so you can see some RBC fragments in affected vessels

Question 12

Why do you see “onion-skinning” in arterioles in malignant nephrosclerosis?

Answer 12

as an adaptation to the very high pressures, but it causes vessel lumen narrowing.
(thombus can also occur in these)

Question 13

What kills people with malignant HTN?

Answer 13

Kidney failure.
Cerebral hemorrhage.
Heart failure.

Question 14

How can scleroderma cause malignant HTN?

Answer 14

Collagen deposition in vessels -> reduced flow -> renin release -> HTN.

Question 15

Pattern of damage seen on histology of kidney affected by scleroderma?

Answer 15

Fibrinoid necrosis, mucoid changes, some onion-skinning…

Question 16

2 renal lesions that cause reduced renal blood flow?

Answer 16

Stenosis of renal artery.

Atheroembolus.

Question 17

2 causes of stenosis of renal arteries?

Answer 17

Atherosclerosis.
Fibromuscular dysplasia.
(and… you could have some mass effect occluding the artery from outside)

Question 18

How do atherosclerosis and fibromuscular dysplasia causing renal artery stenosis differ in appearance?

Answer 18

Atherosclerosis: usually one focal area of stenosis.

Fibromuscular dysplaia: alternating areas of stenosis and dilation.

Question 19

3 changes (visible by histology) that happen in the underperfused kidney in renal artery stenosis?

Answer 19

Tubular atrophy.
Interstitial fibrosis.
Juxtaglomerular apparatus hyperplasia.

Question 20

Does unilateral renal artery stenosis affect the opposite kidney?

Answer 20

Yes - renin -> increased BP can cause arteriosclerosis on the opposite kidney.
(more on this in the HTN lecture)
And the other kidney tends to get much bigger. “Goldblatt kidney”

Question 21

Cholesterol emboli… what do they look like in histology?

Answer 21

They’re hard to see… shadows of washed out crystals surrounded by giant cells. (another one of these “why do we care if we’re not going to be pathologists?” things)

Question 22

What kind of infarct would cause a wedge-shaped area of necrosis/scar in the kidney?

Answer 22

Occlusion of an interlobar artery.

Question 23

What pattern of kidney damage will be seen in the context of acute blood loss? (e.g. obstetric emergency)

Answer 23

Cortical necrosis.
(this is confusing, given other lecturers said outer medulla is most susceptible to ischemia… perhaps the cortex is less able to adjust to acute changes? chronic ischemia would more affect medulla? Unclear.)

Question 24

Pattern of kidney damage caused by sickle cells?

Answer 24

Ischemia with papillary necrosis (in some cases).

This damages the medulla more…. perhaps because it’s more chronic ischemia than the acute seen in extravasation.

Question 25

Do thrombotic microangiopathies affecting the kidney usually only affect the kidney?

Answer 25

No - these tend to be systemic disorders that also have renal manifestations (in the form of thrombi).

Question 26

3 things you can detect in the blood that suggest a microangiopathy is taking place?

Answer 26

Thrombocytopenia.
Schistocytes (damaged RBCs from squeezing past thrombi).
Elevated LDH / decreased haptoglobin (evidence of RBC lysis).

Question 27

5 examples of thrombotic microangiopathies?

Answer 27

Hemolytic uremic syndrome (HUS).
Thrombotic Thrombocytopenic Purpura (TTP).
Disseminated Intravascular Coagulation (DIC).
Toxemia of pregnancy (pre-eclampsia / eclampsia).
Antiphospholipid syndrome (APS).

Question 28

Hallmark of hemolytic uremic syndrome?

Answer 28

Vascular wall damage - that’s what sets of the thrombotic microangiopathy.

Question 29

2 causes of HUS?

Answer 29

Typical: Shiga-like toxin -with diarrhea.
Atypical: Overactivation of complement - without diarrhea.

Question 30

What does renal histology of HUS look like?

Answer 30

Glomerular capillaries are full of thrombus.

Question 31

Hallmark of TTP?

Answer 31

Thrombosis.

TTP has fluctuating neuro involvement. Renal manifestations are less severe vs. HUS.

Question 32

MDTI review: Mechanism of TTP?

Answer 32

Too much von Willibrand Factor (vWF) activity due to lack of ADAMTS13 activity.

Question 33

How do the thrombi in TTP vs. DIC contrast?

Answer 33

TTP: platelet thrombi.
DIC: fibrin thrombi.

Question 34

Precipitating events in pre-eclampsia / eclampsia?

Answer 34

Placental factors cause endothelial injury.

Question 35

Simple definition of pre-eclampsia? When does it become eclampsia?

Answer 35

Pre-eclampsia: Gestational HTN + proteinuria.

Eclampsia: Pre-eclampsia + convulsions.

Question 36

What causes the proteinuria in pre-eclampsia?

Answer 36

Podocyte injury.

Question 37

What do the glomeruli look like in pre-eclampsia?

Answer 37

Bloodless, due to obliteration of the capillary lumen.