Hypertensive Renovascular Disease



Hypertensive Renovascular Disease


A. Brad Farris, III, MD










A nephrectomy in a case of hypertensive renovascular disease shows a characteristic coarsely granular, “fleabitten” surface with scattered petechial hemorrhages image.






This PAS stain shows arterioles image with plump endothelial cells and muscular hypertrophy in a case of hypertensive renovascular disease.


TERMINOLOGY


Abbreviations



  • Hypertension (HTN)


  • Arterionephrosclerosis (ANS)


Synonyms



  • Arterio-/arteriolonephrosclerosis


  • Hypertensive nephrosclerosis


  • Benign nephrosclerosis


  • Malignant nephrosclerosis


Definitions



  • Renal vascular and glomerular disease secondary to hypertension (blood pressure > 120/80 mmHg)


  • Accelerated hypertension, mean blood pressure > 140 mmHg, papilledema, retinal hemorrhage


ETIOLOGY/PATHOGENESIS


Essential Hypertension



  • 95% of cases


  • Evidence for multigenic basis plus environmental factors


  • Risk factors include obesity, lack of exercise, salt intake, black race


  • Other factors: Low birth weight, decreased nephron number, dysmetabolic syndrome


Secondary Causes of Hypertension



  • 5% of cases


  • Renal artery stenosis



    • Atherosclerosis, dysplasia, vasculitis, dissection


    • Increased production of renin by ischemic kidney


  • Neoplasia



    • Pheochromocytoma


    • Adrenal cortical tumors


    • Renin-producing tumors


  • Chronic renal disease


  • Cocaine abuse


  • Hypercoagulable states


Malignant Hypertension



  • May be primary or secondary


  • Renin release causes a cycle of vascular injury followed by more renin release


  • Features of thrombotic microangiopathy


Effect of Hypertension on Arteries and Arterioles



  • Hypertension precedes renal vascular disease



    • Shown in early renal biopsy series of Castleman and Smithwick


    • The more severe the renal vascular disease, the more reduced the glomerular filtration rate and renal blood flow


    • Vascular disease is the result, rather than cause, of hypertension


  • Involves direct injury to endothelium


  • Plasma (and fibrin) insudates into vascular walls


  • Arterial stiffening and increased pulse pressure to afferent arteriolar level leading to hyalinosis


  • Severe hypertension causes renal vascular fibrinoid necrosis (Goldblatt)


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Approximately 30% of adult Americans have hypertension


    • Hypertension accounts for around 25% of end-stage renal disease (ESRD) cases


    • Malignant nephrosclerosis as result of malignant hypertension occurs at rate of 1-2 cases/100,000 per year


  • Age



    • Hypertension appears mostly between mid 40s and mid 50s




      • Renal damage and dysfunction take years to develop and manifest


  • Gender



    • Males have predisposition


  • Ethnicity



    • Disproportionately affects black race


Presentation



  • Hypertension


  • Proteinuria, asymptomatic



    • Related to severity of hypertension


  • Renal dysfunction


  • Accelerated (malignant) hypertension if mean blood pressure > 160 mmHg



    • Papilledema


    • Retinal hemorrhage


    • Congestive heart failure


    • Stroke


    • Encephalopathy


    • Renal insufficiency


    • Microangiopathic hemolytic anemia (MAHA)


Treatment



  • Drugs



    • Antihypertensive agents



      • Diuretics, mineralocorticoid receptor antagonists


      • ACE inhibitors, vasopeptidase inhibitors, renin inhibitors


      • Smooth muscle dilators, endothelin antagonists


      • β-adrenergic blockers, α-adrenoceptor blockers


    • Optimal blood pressure control reduces progression to renal insufficiency and may reverse hypertensive nephrosclerosis


Prognosis



  • ESRD develops in mean of 6 years from onset of azotemia


  • Factors that predispose to renal failure include



    • Increasing age


    • Poor serum glucose control in diabetic patients


    • Level of systolic blood pressure


    • Male gender


    • Black race


    • Elevated uric acid and triglycerides


    • High diastolic blood pressure


  • Malignant hypertension



    • If left untreated, survival is poor (20% 1-year survival)


    • Long-term survival is > 90% if blood pressure is controlled


MACROSCOPIC FEATURES


General Features



  • May be normal in size or slightly reduced in size and weight


  • Capsular surface is usually finely granular


  • Cortical scars may be present


  • Simple cysts may be present


  • Cortex may be thinned


  • Malignant hypertension



    • May be normal or increased in weight to 400 g


    • Petechial hemorrhages secondary to arteriolar necrosis gives “flea-bitten” appearance


    • May be mottled yellow and red if infarcts arise


MICROSCOPIC PATHOLOGY


Histologic Features



  • Subcapsular scars



    • Composed of sclerotic glomeruli, thickened arterioles, and atrophic tubules


    • Result in granular surface of kidney


    • Bulging areas between depressed scars contain spared and hypertrophied nephrons


  • Medium-sized arteries



    • Intimal fibrosis


    • Internal elastic lamina becomes multilayered (fibroelastosis); best seen on elastic stains


    • Smooth muscle hyperplasia


    • Decreased vascular lumen


  • Arterioles



    • Hyaline arteriolosclerosis




      • Afferent arteriolar media is replaced by homogeneous eosinophilic material positive on PAS or Masson trichrome stains


      • Begins under endothelial layer and eventually replaces entire media


  • Glomeruli



    • May have swollen endothelial cells and may thus appear “bloodless” and consolidated


    • Glomerular basement membranes may be duplicated


    • Glomerular mesangial matrix may be increased


    • Global glomerulosclerosis



      • Solidified type: Global solidification without collagenous material in Bowman space


      • Obsolescent type: Glomerular tuft sclerosed and Bowman space filled with collagenous material


    • Segmental glomerulosclerosis



      • Secondary focal segmental glomerulosclerosis (FSGS) may occur, typically with GBM corrugation and periglomerular fibrosis and subtotal foot process effacement


    • Glomerular hypertrophy (compensatory) in spared areas


  • Interstitium and tubules



    • Interstitial fibrosis and mononuclear inflammation


    • Tubular atrophy


    • Tubular hypertrophy in spared areas


  • Histologic features of malignant hypertension



    • Small arteries



      • Mucoid (myxoid) intimal change and endothelial swelling in arterioles, a.k.a. “onion skinning”


      • Fibrinoid necrosis


      • Karyorrhectic debris


      • Occasional neutrophils within endothelium


      • Fibrin thrombi


    • Arterioles



      • Arteriolar occlusion by endothelial swelling/edema-type change


      • Fibrinoid necrosis


      • Fibrin thrombi


    • Glomeruli



      • Segmental necrosis of glomeruli


      • Ischemic retraction of glomeruli with corrugation of GBM


  • Treated hypertension



    • As shown by Pickering and Heptinstall



      • Acute lesions of fibrinoid necrosis and mucoid intimal thickening resolve with adequate treatment


      • Intima becomes fibrous with increased cellularity and elastic fibers


Predominant Cell/Compartment Type



  • Arterial intima


ANCILLARY TESTS


Immunofluorescence



  • IgM and C3 may be present in hyaline layers of arterioles


  • C3 may be present in absence of immunoglobulins


  • Fibrinogen is most common reactant seen on IF in malignant hypertension (in areas of fibrinoid necrosis and glomerular capillary loops)


Electron Microscopy

Jul 7, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Hypertensive Renovascular Disease
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