Diseases InvolvingDiseases Involving

Blood Vessels of the Blood Vessels of the KidneysKidneys

Presented By Prof. Dr.

Nabil Tadros Mikhail MBBS, MS Pathol., PhD Pathol.

Prof. of Pathology Alexandria University - Egypt

Consultant & Chief Pathologist King Fahad Central Hospital

Gizan - KSA

Nearly all renal diseases of the kidney involve the renal blood vessels secondarily.

However the main diseases affecting blood vessels of the kidney are

1.1. Benign nephrosclerosis ,Benign nephrosclerosis ,

2.2. Malignant nephrosclerosisMalignant nephrosclerosis

3.3. Thrombotic microangiopathies. Thrombotic microangiopathies.

Benign NephrosclerosisBenign Nephrosclerosis

I- Benign nephrosclerosisBenign nephrosclerosis

This lesion describe the renal changes in benign hypertension.

Morphology: The kidneys are symmetrically

atrophic with diffuse fine granularity.

Benign nephrosclerosis. The smaller arteries in the kidney have become thickened and narrowed. (Hyaline arteriolosclerosis.) This leads to patchy ischemic atrophy with focal loss of parenchyma that gives the surface of the kidney the characteristic granular appearance (symmetrical)

Slide 21.61

Patchy ischemic atrophy with focal loss of parenchyma that gives the surface of the kidney the characteristic granular appearance (symmetrical)

I- Benign nephrosclerosisBenign nephrosclerosis

Microscopically: The basic changes is Hyaline thickening of the wall of small

arteries and arterioles. (hyaline (hyaline arteriolosclerosis)arteriolosclerosis) . .

Homogenous pink hyaline thickening of vessel wall & narrowing of lumen.

This produces ischemic atrophy of kidney

Slide 21.62

Benign nephrosclerosis.High power view of two arterioles with hyaline deposition, marked thickening of the walls, and narrow lumen.

hyaline deposition, marked thickening of the walls

narrow lumen

II- Malignant NephrosclerosisII- Malignant Nephrosclerosis

II- Malignant nephrosclerosisII- Malignant nephrosclerosis

It is renal lesion associated with malignant hypertension .

The latter is less common than benign hypertension .

Occur in only in 5% of hypertensive patients or may arise denovo.

Malignant hypertensionMalignant hypertension Pathogenesis: The initial event appear to be some form

of vascular damage to the kidney. This results in increase permeability to

fibrinogen and platelet deposition . This lead to fibrinoid necrosis of

arterioles and platelet deposition,

Malignant hypertensionMalignant hypertension Pathogenesis:…

Mitogenic factors from platelets (PDGF) cause intimal hyperplasia of vessels resulting in hyperplastic arteriolosclerosis typical of malignant hypertension.

The kidney is markedly ischemic and there is increased level of renin and aldosterone

Malignant hypertension

Morphology: The kidney is normal or slightly

shrunken. Small pinpoint hemorrhage may

appear on cortical surface due to rupture of arterioles .

It has flea bitten appearance.

In malignant nephrosclerosis. The kidney demonstrates focal small pinpoint hemorrhages.

Giving a flee bitten appearance

Malignant hypertensionMalignant hypertension

Microscopically: Larger arterioles shows a characteristic

finding of hyperplastic arteriolosclerosis. It show onion-skin concentric laminated

thickening of the wall of arterioles with progressive narrowing of the lumen.

Malignant hypertensionMalignant hypertension

Microscopically: In addition, small blood vessel shows fibrinoid

necrosis and the wall show homogenous granular eosinophilic appearance.

Also there is infiltration of inflammatory cells giving rise to necrotizing arteriolitis which may extend to glomeruli

Thickening of the arterial wall with malignant hypertension also produces a hyperplastic arteriolitis The arteriole has an "onion skin" appearance.

Malignant hypertension leads to fibrinoid necrosis of small arteries as shown here. The damage to the arteries leads to formation of pink fibrin--hence the term "fibrinoid

Malignant hypertension Clinical picture:Clinical picture:

It is characterized by Marked elevation of blood pressure

(diastolic pressure more than 120 mm/Hg)(diastolic pressure more than 120 mm/Hg) Papilledema Encephalopathy Renal failure Cardiac abnormalities.

Malignant hypertension

Clinical picture:…Clinical picture:… The common presenting symptoms are

related to increase of intracranial pressure

Headache Vomiting Visual disturbances

Malignant hypertension

Malignant hypertension require immediate treatment .

Death may occur particularly in those without treatment, due to

Renal failure Cerebrovascular accident Cardiac failure.

IIIIIIThrombotic microangiopathyThrombotic microangiopathy

III- Thrombotic microangiopathy

These represent clinical syndrome characterized by widespread thrombosis in microcirculation and

clinically by Microangiopathic hemolytic anemia, Thrombocytopenia In some cases renal failure. These include hemolytic uremic syndrome and

thrombotic thrombocytopenic purpura.

III- Thrombotic microangiopathyIII- Thrombotic microangiopathy

These include

Hemolytic uremic syndrome Thrombotic thrombocytopenic purpura.

11 - -Hemolytic Uremic Syndrome (HUSHemolytic Uremic Syndrome (HUS))

It can occur in adults or children.

A- adult HUSA- adult HUS:: It is usually due to damage of

endothelium as a result of exposure to certain drugs or radiation

B- Children HUSB- Children HUS

Most cases usually follow infectious gastroenteritis cause by E coli strain which elaborate toxins that produce damage of endothelium .

This damage initiate platelet activation and thrombosis.

Ingestion of infected meat (hamburger) is a risk factor.

B- Children HUSB- Children HUS

Clinically, there is Bloody diarrhea , Hematemesis.

Later on Oliguria and Renal failure develop.

The disease is one of the main cause of renal failure in children.

2 -Thrombotic thrombocytopenic purpura Thrombotic thrombocytopenic purpura

(TTP(TTP))

TTP is another microangiopathy characterized by its occurrence in females mainly. Thrombocytopenia, microangiopathic hemolytic anemia , neurological symptoms and renal failure may develop.

2 -Thrombotic thrombocytopenic purpura Thrombotic thrombocytopenic purpura

(TTP(TTP))

Pathogenesis: TTP is not due to endothelial damage

(unlike HUS) TTP is due to deficiency of cleaving

protease enzyme (metalloprotease), that normally degrade very high molecular weight vonWillibrand factor (vWF) .

TTP pathogenesis

In the absence of this enzyme vWF accumulate in plasma and promote platelet aggregation through out circulation.

A small platelet-fibrin thrombus is seen in a glomerular capillary above the arrow. This occurred in a patient with thrombotic thrombocytopenic purpura (TTP).

Slide 21.65

A small platelet-fibrin thrombus is seen in a glomerular capillary above the arrow. (MSB stain for fibrin)