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60

Clinical Case:  A 10 year old male presents to his local PCP with substantial hematuria.  U/A reveiled proteinuria with red blood cell casts.  His history is significant for deafness and vision problems.   Renal biopsy revealed a pattern of thickening and thinning of the GBM consistent with 'basket-weave' appearance.  A skin biopsy revealed a lack of alpha5 staining.

What does this child have?

Alport Syndrome

61

Thin Basement Membrane Lesion (Benign Familial Hematuria)

  • manifested clinically as familial asymptomatic hematuria.  
  • mutation in alpha3 or alpha 4 of type IV collagen.  autosomal recessive.
  • homogenous pts may appear like Alport syndrome and may progress to renal failure.
  • found on routine U/A 
  • morphology: diffuse thinning of GBM to 150-250nm.
  • renal function normal but may have mild to mod proteinuria.  good prognosis.
  • needs to be distinguished from IgA nephropathy and Alport syndrome.

62

Chronic Glomerulonephritis

  • can come from IgA nephropathy, membranous nephropathy, MPGN, FSGS, crescentic GN, poststreptococcal GN, or unknown.
  • morphology: cortex is thinned, granular cortical surfaces, ↑ peripelvic fat.
    • obliteration of glomeruli ⇒ acellular eosinophilic masses.
    • accompanied by HTN, arterial and arteriolar sclerosis, atrophy of associated tubules, irregular interstitial fibrosis, mononuclear leukocytic infiltration.
    • dialysis ⇒ arterial intimal thickening, extensive deposition of calcium oxalate crystals, acquired cystic disease
    • uremic changes: pericarditis, secondary hyperparthyroidism, LV hypertrophy, uremic pneumonitis, uremic gastroenteritis.
  • presentation: develops insidiously then slowly goes to renal insufficiency or death from uremia.  have nonspecific  complaints like loss of appetite, anemia, vomiting, or weakness.
    • most pts HTN, have cerebral or cardiovascular manifestations.
    • relentlessly progressive.
      • nephrotic pts: glomeruli obliterated ⇒ ↓ GFR, protein loss in urine ↓.
    • if don't get dialysis or transplant, will die.

63

Clinical Case: 

A 65 y/o male presents to his PCP with a complaint of feeling weak and vomiting.  He has a history of FSGS and HTN.  Biopsy of his kidneys shows cortical thinning and obliteration of the glomeruli as well as arterial sclerosis.

What does he have?

Chronic Glomerulonephritis

64

Lupus Nephritis

  • presentation: recurrent microscopic or gross hematuria, nephritic syndrome, nephrotic syndrome, chronic renal failure, and HTN.

65

Clinical Case:

A 26 y/o female presents to her PCP with a complaint of periodic hematuria.  She is found on U/A to have hypercholesterolemia, heavy proteinuria.  On U/A she si found to have fatty casts.  She is ANA positive.

What does she have?

Lupus nephritis

66

Henoch-Schönlein Purpura

  • presentation: purpuric skin lesions on extensor surfaces of arms and legs and buttocks, abdominal pain, vomiting, intestinal bleeding, nonmigratory arthralgia, renal abnormalities.
    • renal problems = gross or microscopic hematuria, nephritic syndrome, nephrotic syndrome or a combo.  
    • adults may get rapidly progressive GN with crescents.
    • mostly kids 3-8 yrs but may be in adults (renal more severe)
    • strong background of atopy in 1/3 pts, onset follows upper resp infection
  • IgA deposited in glomerular mesangium similar to IgA nephropathy
  • morphology: vary from mild focal mesangial proliferation to diffuse mesangial proliferation or endocapillary to crescentic GN.
    • IF: deposition of IgA, some IgG and C3 in mesangial region.
    • lesions: subepidermal hemorrhages and necrotizing vsculitis of small vessels in dermis.
    • vasculitis can be in other organs such as GI or rarely kidney.
  • prognosis: excellent in kids, worse if have diffuse lesions, crescents or nephrotic syndrome.

67

Clinical Case:

A 5 year old girl presents to her pediatrician with purplish lesions on her buttocks and the front of her arms.  Her mother reports that she has reddish urine on and off for the past 2 months.  She is allergic to pollen and cat dander.  Biopsy of her kidney reveals IgA deposits in the mesangium on IF.

What does this girl have?

Henoch-Schönlein Purpura

68

Bacterial Endocarditis-Associated Glomerulonephritis

  • an immune complex nephritis initiated by complexes of bacterial antigen and antibody.  occurs with bacterial endocarditis.
  • presentation: hematuria and proteinuria.  can have acute nephritic presentation or RPGN.
  • IF: glomerular immune deposits.

69

Clinical Case:

A 32 year old male was found to have a systolic ejection murmur following a serious skin infection one month earlier.  He was placed on antibiotics but showed up to the ER with complaints of blood in his urine after 1 day.  U/A revealed proteinuria and biopsy of the kidneys revealed immune complexes.

What does this patient have?

Bacterial Endocarditis-Associated GN

70

Diabetic Nephropathy

  • a leading cause of chronic renal failure.
  • most common lesions of glomeruli: non-nephrotic proteinuria, nephrotic syndrome, chronic renal failure.
  • causes hyalinizing arteriolar sclerosis, papillary necrosis, and tubular lesions.
  • morphology: capillary basement membrane thickening, diffuse mesangial sclerosis, nodular glomerulosclerosis.  appear same in type I and type II diabetes.
  • caused by metabolic defect = insulin deficiency, hyperglycermia, or glucose intolerance. ⇒ ↑ type IV collagen and fibronectin and ↓ heparan sulfate proteoglycan
  • nonenzymatic glycosylation of proteins causes glomerulopathy
  • end stage characterized by ↑ GFR, ↑ glomerullar capillary pressure, glomerular hypertrophy, ↑ glomerular filtration area.
  • two processes: metabolic defect ⇒ thickened GBM and ↑ mesangial matrix; hemodynamic effects help develop glomerulosclerosis.  both ⇒ loss of podocytes.

71

Clinical Case:

A 65 year old female presents to the ER with hematuria and mild proteinuria.  She was diagnosed with type II diabetes ten years ago.  Renal biopsy shows thickening of the GBM, mesangial sclerosis, and nodular glomerulosclerosis.

What does this woman have?

Diabetic Nephropathy

72

Amyloidosis

  • deposition of light-chain AA in the glomeruli.
  • stains on Congo red in mesangium and capillary walls. can be in interstitium and blood vessel walls
  • obliterates glomerulus.
  • presentation: nephrotic syndrome, die of uremia.  kidney size normal or increased.

73

Clinical Case: 

A 50 year old male presents to the ER with hematuria and proteinuria.  A biopsy of his kidney on Congo red stain revealed deposits in the glomeruli.  

What does this patient have?

Amyloidosis

74

Fibrillary Glomerulonephritis

  • fibrillar deposits in mesangium and glomerular capillary walls.  resemble amyloid but don't stain on Congo, also are larger in diameter than amyloid fibrils.
  • light microscopy: shows membranoproliferative or mesangioproliferative patterns
  • IF: selective deposition of polyclonal IgG of IgG4 subclass, complement C3, and Igkappa and Iggamma light chains.
  • presentation: nephrotic syndrome, hematuria, progressive renal insufficiency.
    • recurs in kidney transplants.

75

Clinical Case:

A 60 year old female presents to her PCP with a complaint of bloody urine.  U/A shows massive proteinuria and hematuria.  Blood analysis shows hypercholesterolemia and hyperlipidemia.  Biopsy shows fibrils in the mesangium that do not stain Congo red and reveals deposits of IgG, complement C3, and light chain Iggamma.

What does this patient have?

Fibrillary Glomerulonephritis

76

Immunotactoid Glomerulopathy

  • microtubular deposits, 30-50 nm in width.  have circulating paraproteins or monoclonal Ig deposition in glomeruli.

77

Clinical Case:

A 72 year old male presents to her PCP with complaints of bloody urine.  U/A shows hematuria and proteinuria. Biopsy of the kidney reveals Ig deposition in the glomeruli that are microtubular in shape.

What does this man have?

Immunotactoid Glomerulopathy

78

Essential Mixed Cryoglobulinemia

  • deposits of cryoglobulins made of IgG-IgM complexes induce cutaneous vasculitis,, synovitis, and proliferative GN (mostly MPGN type I).
  • associated with hep C

79

Plasma Cell Dyscrasias

  • can induce glomerular lesions

80

Multiple Myelomas

  • produce circulating monoclonal Ig associated with amyloidosis, deposition of monoclonal Ig in GBM, distinctive nodular glomerular lesions ⇒ depositionn of nonfibrillar light chains
  • aka monoclonal Ig deposition disease
  • characterized by deposition of Igkappa or Iggamma light chains in glomeruli, PAS-pos mesangial nodules, lobular accentuation, and mild mesangial hypercellularity.  
  • presentation: proteinuria or nephrotic syndrome, HTN, progressive azotemia.

81

Clinical Case:

A 58 year old female presents to her PCP with a complaint of bloody urine.  Upon U/A proteinuria and hematuria were noticeable as well as lipids in the urine.  Her creatinine and BUN were elevated while her GFR was decreased.  She has a history of hypertension.  Upon biopsy of the kidney, deposits of Igkappa were found in the glomeruli.

What does this patient have?

Multiple myeloma

82

Acute Tubular Injury (AKI)/ Acute Tubular Necrosis (ATN)

  • characterized by acute diminution of renal function and often has tubular injury.  reversible lesion.
  • most common cause of acute renal failure (rapid ↓ renal function and urine flow, <400mL per day) from ischemia, toxic injury to tubules, acute tubulointerstitial nephritis, and urinary obstruction.
  • ischemic AKI - from poor blood flow with hypotension and shock.
  • nephrotoxic AKI - from drugs, contrast, poisons, organic solvents. 
  • hemolytic crises ⇒ hemoglobinura; skeletal muscle injuries ⇒ myoglobinuria.
    • ⇒ intratubular hemoglobin or myoglobin casts
  • critical events: tubular injury, disturbed blood flow.
    • tubule cell injury - sensitive to ischemia and toxins.
      • reversible changes = loss of polarity/brush border from redistribution of membrane proteins, ↑ Na delivery to distal tubules ⇒ ↑ tubuloglomerular feedback ⇒ vasoconstriction;  injured cells detach ⇒ luminal obstruction, ↑ intratubular pressure, ↓ GFR
      • irreversible changes = necrosis and apoptosis ⇒ tubular back-leak ⇒ ↓ tubular flow.
    • disturbed blood flow - intrarenal vasoconstriction ⇒ ↓ glomerular blood flow, ↓ oxygen delivery to outer medulla tubular cells
      • vasoconstriction caused by ↓ NO, ↓ PGI2, ↑ Renin-angiotensin, ↑ endothelin
  • re-epithelization depends on growth factors and cytokines from tubular cells or inflammatory cells.
    • TGF-alpha, insulin-like growth factor 1, and hepatocytes growth factor important
  • morphology: focal tubular epithelial necrosis, large skip areas btw necrotic points with rupture of basement membrane and occlusion by casts. mostly in proximal tubule and thick ascending limb in renal medulla.
    • tubular damage = loss of brush borders, simplification of cell structure, cell swelling, vacuolization, sloughing of non-necrotic tubular cells into lumen.
    • eosinophilic hyaline casts and granular casts in distal tubules and collecting ducts. made of Tamm-Horsfall protein and plasma proteins.
    • ischemic AKI - interstitial edema and leukocytes in dilated vasa recta. flattened epithelial cells with hyperchromatic nuclei and mitotic figures.
    • toxic AKI - acute tubular injury mostly proximal convoluted tubules.
      • mercury chloride causes acidophilic inclusions then necrosis, desquamate, and calcify.
      • carbon tetrachoride accumulates neutral lipids in injured cells causes fatty change then necrosis.
      • ethylene glycol causes ballooning and hydropic or vacuolar degeneration of proximal convoluted tubules ⇒ calcium oxalate crystals.
  • presentation: 3 stages.
    • 1. initiation: 36 hrs long, slight ↓ urine output with ↑ BUN.  oliguria from ↓ blood flow and ↓ GFR.
    • 2. maintenance: urine output btw 40-400 mL/day (oliguria), salt and water overload, ↑ BUN, hyperkalemia, metabolic acidosis, uremia. tx: dialysis.
    • 3. recovery: ↑ urine volume (up to 3L/day), ↑ urinary loss of water sodium and potassium, hypokalemia, ↑ risk infection.
  • 50% do not have oliguria = nonoliguric AKI usually with nephrotoxins.

83

Clinical Case:

A 72 year old female presents to her PCP with complaints of prolonged bloating and decreased urine production.  Blood analysis shows her to be acidotic and hyperkalemic with an ↑ BUN.  Biopsy revealed focal areas of necrosis in her thick ascending limb with large areas of  normal tubular cells inbetween.

What does she have?

AKI/ATN

84

Acute vs Chronic Tubulointerstitial Nephritis

  • acute = rapid onset with interstitial edema, leukocyte infiltration (eosinophils and neutrophils) of interstitium and tubules, and focal tubular necrosis.
  • chronic = infiltration with mononuclear leukocytes, interstitial fibrosis, widespread tubular atrophy.
  • presentation of tubular defects: impaired concentration of urine, polyuria or nocturia, salt wasting, diminished ability to excrete acids (metabolic acidosis), isolated defects in tubular reabsorption or secretion.

85

Acute Pyelonephritis

  • caused by bacterial infection, associated with UTI.  usually gram (-) bacilli: E. coli, Proteus, Klebsiella, Enterobacter.  Also Strep faecalis and staph.
    • in immunocompromised can be from viruses: Polyomavius, CMV, adenovirus.
  • from bacteremia or ascending spread (most common)
    • starts in distal urethra and introitus, then moves to bladder, and can be aided by urinary tract obstruction and stasis or urine.  
    • incompetence of vesicoureteral reflex allows ascension to kidney, allows reflux into ureter.
      • usually from congenital absence or shortening of intravesical portion of ureter
    • intrarenal reflux = infected bladder urine propelled upward to renal pelvis and into renal parenchyma through open ducts at tips of papillae.
      • common in upper and lower poles of kidney
  • morphology: patchy interstitial suppurative inflammation, intratubular aggregates of neutrophils, and tubular necrosis. damage mostly in upper and lower poles.
    • early = limited to interstitium.
    • glomeruli usually okay until late but are affected in fungal varieties.
    • complications:
      • papillary necrosis in diabetics and pts with urinary tract obstruction.  distal 2/3 of pyramid is gray-white to yellow necrosis.  has coagulative necrosis with preservation of tubule outlines
      • pyonephrosis: with total or almost complete obstruction high in urinary tract. suppurative exudate fills rnal pelvis, calyces, and ureter with pus.
      • perinephric abscess: extnsion of pus through renal capsule into perinephric tissue
    • healing: macrophages, plasma cells, and lymphocytes come in and cause irregular scars = fibrous depressions on cortical surface. have tubular atrophy, interstitial fibrosis, lymphocytic infiltrate in patchy, jigsaw pattern with preserved parenchyma around it = pyelonephritic scar.
      • associated with inflammation, fibrosis, and deformation of underling calyx and perlvis.
  • presentation: predisposing factors = urinary tract obstruction, catheters, vesicoureteral reflux, pregnancy, female, preexisting renal lesions, diabetes mellitus, immunosuppression/deficiency.
    • sudden pain at costovertebral angle with fever and malaise, dysuria, frequency, urgency, pyuria, pus casts (leukocyte casts).
    • usually recovers in a few days with antibiotics.  may persist with bacteremia for years.
      • superimposition of papillary necrosis ⇒ acute renal failure.
  • polyomavirus nephropathy: usually in allograft pts.  viral infection of tubular epithelial cell nuclei ⇒ nuclear enlargement and intranuclear inclusions made of virions.

86

Clinical Case:

A 30 year old female presents to the ER for fever and tiredness.  She also complains that she needs to urinate more frequently than normal and has a hard time making it to the bathroom.  She has a medical history that includes DM type I and HTN.  U/A shows pus casts and pyuria.  Biopsy reveals coagulative necrosis with preserved tubules.

What does she have?

Acute Pyelonephritis

87

Chronic Pyelonephritis

  • caused by bacterial infection, associated with UTIusually gram (-) bacilli: E. coli, Proteus, Klebsiella, Enterobacter.  Also Strep faecalis and staph.
  • in immunocompromised can be from viruses: Polyomavius, CMV, adenovirus.
  • from bacteremia or ascending spread (most common)
    • starts in distal urethra and introitus, then moves to bladder, and can be aided by urinary tract obstruction and stasis or urine.
    • incompetence of vesicoureteral reflex allows ascension to kidney, allows reflux into ureter.
    • usually from congenital absence or shortening of intravesical portion of ureter
    • intrarenal reflux = infected bladder urine propelled upward to renal pelvis and into renal parenchyma through open ducts at tips of papillae.
      • common in upper and lower poles of kidney
  • chronic tubulointerstitial inflammation and renal scarring associated with pathologic involvement of the calyces and pelvis.
  • ⇒ end-stage kidney disease
  • 2 forms:
    • 1. Reflux Nephropathy: more common form.  in early childhood from UTI on top of congenital vesicoureteral reflux and intrarenal reflux ⇒ uni or bilateral damage (scarring and atrophy) ⇒ chronic renal insufficiency.
    • 2. Chronic Obstructive Pyelonephritis: recurrent infections on top of diffuse or localized obstructive lesions ⇒ inflammation and scarring ⇒ chronic pyelonephritis.
      • parenchymal atrophy, can be bilateral ⇒ renal insufficiency.
        • unilateral when occurs with calculi and unilateral obstructive anomalies of ureter.
  • morphology: kidneys irregularly scarred, asymmetric (when bilateral).
    • hallmarks: coarse, discrete, corticomedullary scars overlying dilated, blunted, or deformed calyces, flattening of papillae.
    • mostly upper and lower poles.
    • tubules have atrophy as well as hypertrophy or dilation.  can have colloid casts
    • chronic interstitial inflammation and fibrosis in cortex and medulla.
    • can have pus casts.
    • obliterative intimal sclerosis in scarred areas, pts with HTN have hyaline arteriosclerosis.
    • Xanthogranulomatous pyelonephritis: rare form of chronic pyelonephritis with accumulation of foamy macrophages with plasma cells, lymphocytes, polymorphonuclear leukocytes, and giant cells.
      • associated with Proteus infections and obstructions.
      • produce large, yellowish orange nodules that can be confused with renal cell carcinoma.
  • presentation: insidious in onset or present as recurrent acute pyelonephritis with back pain, fever, pyuria, bacteriuria.  
    • with reflux may be silent and present with renal insufficiency and HTN or find pyuria/bacteriuria as random finding.
    • reflux discovered when kids have HTN.
    • have polyuria and nocturia.
    • asymmetrically contracted kidneys with coarse scars, and blunting and deformity of calyceal system. 
    • proteinuria is mild, may develop secondary FSGS.  poor prognosis.  

 

88

Clinical Case:

A 8 year old male presents to his PCP for a routine physical and HTN is discovered.  He has had issues with bed wetting recently and frequent trips to urinate.  U/A shows low levels of proteinuria as well as a few colloid casts and pus casts.  Imaging shows asymmetrically scarred kidneys.

What does this child have?

Chronic Pyelonephritis

89

Acute Drug-Induced Interstitial Nephritis

  • occurs with sulfonamides, synthetic penicillins, synthetic antibiotics (Rifampin), diuretics (thiazides), NSAIDs, and others (allopurinol, cimetidine).
  • begins 15 days after exposure with fever, eosinophilia, rash, and renal abnormalities (hematuria, mild proteinuria, and leukocyturia).
    • 50% have ↑ serum creatinine level or acute renal failure with oliguria.  see in elderly.
  • immune response idiosyncratic and not dose-related
  • tubulitis = infiltration of tubules by lymphocytes.  very common.
  • serum IgE levels ↑, IgE plasma cells and basophils in lesions ⇒ involves late phase IgE-mediated hypersensitivity (type I).
  • mononuclear or granulomatous infiltrate and positive for drug haptens = type IV hypersensitivity (T cell).
  • morphology: interstitium has pronounced edema and infiltration by mononuclear cells (lymphocytes and macrophages).  Eosinophils and neutrophils in clusters.
    • interstitial non-necrotizing granulomas = have giant cells.  with thiazides and methicillin.
    • glomeruli unaffected except with NSAIDs with minimal change disease and nephrotic syndrome.
  • presentation: may have irreversible damage in elderly.