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BRS Pathology - Chapter 17 - Kidney and Urinary Tract


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What are in utero manifestations of complete/bilateral renal agenesis? How common is this?
Oligohydramnios occurs because the renal system is not excreting fluids swallowed by the fetus.

This results in the oligohydramnios sequence: multiple fetal abnormalities including hypoplastic lung, defects in extremities, etc.
What are the clinical manifestations of the nephrotic syndrome?
Massive proteinuria: >4 g per day
Hypoalbuminemia: <3 g per deciliter
Generalized Edema
Hyperlipidemia and Hypercholesterolemia: due to increased hepatic lipoprotein synthesis
What is Minimal Change Disease?

Prototypical nephrotic syndrome. Most often in young children but can occur in older individuals.
Light microscopy shows normal glomeruli.
Electron microscopy is normal except for effacement of epithelial foot processes.
Responds well to steroid therapy.

Pathogenesis may be related to mutations in nephrin.
What is focal segmental glomerulosclerosis?

Like the name: focal, involving only a subset of glomeruli, segmental, involving only a portion of the glomerular tuft.
Symptoms include nephrotic syndrome or non-nephrotic proteinuria. Like minimal change disease, there is a loss of foot processes. There is also sclerosis -- collapse of the basement membranes, increase in matrix, and hyalinosis of the capillary wall with possible obstruction.
Responds poorly to steroids.
What is membranous glomerulonephritis?

An immune complex disease of unknown etiology that causes the nephrotic syndrome and azotemia.
Light microscopy shows thickened capillary walls due to a five to 10 fold thickening of the basement membrane. Epimembranous (subepithelial) deposits with a spike and dome appearance. Granular pattern on immunofluorescence.
What is diabetic nephropathy?

Dramatic thickening of the entire glomerular basement membrane, seen by electron microscopy.
Other changes include an increase in mesangial matrix in both a diffuse and nodular (Kimmelstiel-Wilson nodules) pattern.
What is renal amyloidosis?
Presents with nephrotic syndrome, due to subendothelial and mesangial amyloid deposits.
Often caused by chronic inflammatory diseases such as rheumatoid arthritis or plasma cell disorders such as multiple myeloma.
What are the five patterns of lupus nephropathy?
Type 1: no observable renal involvement
Type 2: mesangial cell and matrix proliferation, with slight proteinuria and minimal hematuria
Type 3: focal proliferative -- not all glomeruli involved, but some severely damaged
Type 4: diffuse proliferative -- all glomeruli involved with inflammation, thromboses, mesangial proliferation, and scarring. Also see wire loop abnormalities, endothelial cell proliferation, and subendothelial immune complex deposition.
Type 5: membranous form -- same as primary membranous glomerulonephritis
What are the characteristics of the nephritic syndrome?
Oliguria, azotemia, hypertension, hematuria with red cell casts. Patients often report having "smoky brown urine".
What is poststreptococcal glomerulonephritis?
Prototype of the nephritic syndrome. Immune complex disease due to GAS infection. 95% show complete recovery, but a small minority develops rapidly progressive glomerulonephritis.
Causes an inflammatory reaction with renal surface petechiae, enlarged, hypercellular glomeruli, normal basement membrane thickness, subepithelial bumps, and "lumpy bumpy" immunofluorescence.
What is rapidly progressive (crescentic) glomerulonephritis (RPGN)?

Nephritic syndrome that progresses to renal failure within weeks or months. Crescents are formed by fibrin deposition in Bowman space and proliferation of epithelial cells.

Type I: anti-GBM disease
Type II: poststreptococcal (50%)
Type III: pauci-immune, associated with ANCAs
What is Goodpasture's syndrome?
Nephritic syndrome, pneumonitis with hemoptysis, and RPGN crescentic glomerulonephritis due to anti-glomerular basement membrane antibodies.

Fluorescent antibody staining demonstrates a linear pattern.
What is focal glomerulonephritis?
Focal and segmental inflammatory changes (contrast to sclerotic changes in focal segmental glomerulosclerosis).
Due to immune complexes, often secondary to SLE, subacute bacterial endocarditis, polyarteritis nodosa, Goodpasture's syndrome, Wegener granulomatosis, and IgA nephropathy. Can also be idiopathic.
What is Alport syndrome?

Hereditary nephritis associated with nerve deafness, and ocular disorders (lens dislocation, cataracts).
Due to a mutation of the Alpha-5 chain of type IV collagen, often causes end-stage renal disease by 30 years of age.
Microscopically, irregular glomerular basement membrane thickening/thinning with foci of splitting of the lamina densa.

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