Kidney non-tumor - Malignant hypertension and accelerated nephrosclerosis

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Kidney non-tumor

Blood vessel disorders

Malignant hypertensiony and accelerated nephrosclerosis

Reviewers: Nikhil Sangle, M.D. (see Reviewers page)
Revised: 26 December 2012, last major update August 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

General
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● Also called hypertensive emergency, malignant nephrosclerosis
● Severe hypertension with acute impairment of one or more organ systems (especially CNS, cardiovascular, renal) that may cause irreversible organ damage

Pathophysiology
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● Vascular damage (due to chronic hypertension, arteritis, coagulopathy) increases permeability of small vessels to fibrinogen and other plasma proteins
● This causes endothelial injury and platelet deposition, which causes fibrinoid necrosis
● Kidneys become ischemic, which stimulates renin-angiotensin system to produce angiotensin II, which causes renal vasoconstriction, as well as increased aldosterone secretion and salt retention, which elevate blood pressure even further
● May be related to increased TRPC3 expression in vascular endothelium (Dtsch Med Wochenschr 2009;134:2224)

Clinical features
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● Usually associated with pre-existing hypertension, glomerulonephritis or reflux nephropathy
● Rarely caused by juxtaglomerular cell tumor (J Med Assoc Thai 2012;95 Suppl 2:S251, J Hypertens 2012;30:974)
● 1-5% of patients with hypertension; higher frequency in young men, African-Americans
● Symptoms: diastolic blood pressure 130 mm or more, cardiac symptoms, encephalopathy, headache, nausea, vomiting, loss of consciousness, proteinuria and renal failure
● Treatment: antihypertensive therapy before irreversible renal lesions develop
● Renal survival has improved; mean proteinuria is important prognostic factor (Nephrol Dial Transplant 2010;25:3266)

Gross description
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● "Flea bitten" appearance of kidney due to pinpoint petechiae on cortical surface

Gross images
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Various images

Micro description
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● Fibrinoid necrosis of arterioles, hyperplastic arteriolitis (onion skinning) due to concentric layering of collagen
● May see necrotizing glomerulitis, wrinkling and collapse of capillary walls and small crescents
● Myointimal hyperplasia and hypertropy is associated with acute or persistent severe high blood pressure
● Necrotizing arteriolitis: fibrinoid necrosis of afferent arteriole, often superimposed on hyperplastic or hyaline lesions; media has deposits of deeply eosinophilic and fibrillar material containing fibrin and fibrinogen
● Early changes: profound intimal thickening by myxoid connective tissue, reducing lumen
● Late changes: scarring and concentric thickening of vessel wall by myointimal cells and deposition of basement membrane type material (onion skinning)

Micro images
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Various images

TRPC3 expression

Virtual slides
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Onion-skinning of vessels

Immunofluorescence
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● Occasional fibrin, fibrinogen, IgM and complement

Electron microscopy description
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● Swollen endothelium
● May be focally disrupted from glomerular basement membrane by accumulation of electron-dense material

End of Kidney non-tumor > Blood vessel disorders > Malignant hypertension and accelerated nephrosclerosis

Ref Updated: 8/24/12

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