Renal- Pathology Flashcards
Note that the presence of casts in urine indicates that hematuria/pyuria is of glomerular or renal tubular origin
Bladder cancer, kidney stones- no casts, hematuria present
Acute cystitis- pyuria, no casts
When are RBC casts seen in urine?
Glomerulonephritis, malignant HTN
When are WBC casts seen in urine?
tubulointerstitial inflammation, acute pyelonephritis, transplant rejection
When are fatty casts seen in urine?
nephrotic syndrome
When are granular (muddy brown) casts seen in urine?
Acute tubular necrosis
When are waxy casts seen in urine?
ESRD/chronic renal failure
When are hyaline casts seen urine?
nonspecific, can be a normal finding, and often seen in concentrated urine samples
What is focal glomerular disease?
less than 50% of glomeruli involved (e.g. focal segmental glomerulosclerosis)
diffuse= 50+%
“Membranous” renal disease means what?
thickening of the glomerular basement membrane (e.g. membranous nephropathy)
Describe nephritic syndrome
an inflammatory process that leads to disruption of the GBM. When it involves the glomeruli, it leads to hematuria and RBC casts in the urine
What are the other signs of nephritic syndrome?
HTN (due to salt retention)
elevated BUN and creatine
oliguria
proteinuria often in the subnephrotic range (less than 3.5g/day) but can be worse
What diseases fall under the umbrella of nephritic syndrome?
Acute poststreptococcal glomerulonephritis
Rapidly progressive glomerulonephritis
IgA nephropathy (Berger disease)
Alport syndrome
Membranoproliferative glomerulonephritis
Describe Acute poststreptococcal glomerulonephritis
acute disease seen commonly in children, appearing ~2 weeks after a group A strep infection of the pharynx or skin (resolves spontaneously), and caused by deposition of immune complexes in the kidneys (Type III hypersensitivity)
What is this?
Acute poststreptococcal glomerulonephritis, marked by enlarged and hypercellular glomeruli
Acute poststreptococcal glomerulonephritis with the classic ‘starry sky’ granular appearance. What causes this?
due to IgG, IgM, and C3 deposition along the GBM and mesangium
Below: EM showing classic subepithelial humps
What additional lab findings are seen in acute poststreptococcal glomerulonephritis?
elevated anti-DNase B titers
decreased complement levels
How does acute poststreptococcal glomerulonephritis present?
nephritic syndrome
peripheral and periorbital edema
cola-colored urine and HTN
Describe rapidly progressive (cresentic) glomerulonephritis (RPGN)
Onset of rapidly deteriorating renal function (days to weeks) (poor prognosis) that can be seen in Goodpasture syndrome, microscopic polyangiitis, and granulomatosis with polyangiitis (Wegener)
What is Goodpoasture syndrome?
type II hypersensitivity with Abs to GBM and alveolar basement membrane (linear IF-below)
What is the classic appearance of RPGN in LM?
crescent moon shape formation (consists of fibrin and plasma proteins (e.g. C3b) with glomerular parietal cells, monocytes, and macrophages
What ANCA is associated with Wegener?
PR3-ANCA (aka c-ANCA)
What ANCA is associated with Microscopic polyangiitis?
MPO-ANCA (p-ANCA)
Diffuse proliferative glomerulonephritis (DPGN)
due to SLE and membranoproliferative glomerulonephritis (most common cause of death in SKE)
often presents as nephrotic and nephritic syndrome concurrently
IgA nephropathy findings on LM, IF, and EM
LM- mesangial proliferation
EM- mesangial IC deposits
IF- IgA based IC deposits in mesangium
What causes Alport syndrome?
mutation in type IV collagen causing thinning and splitting of glomerular basement membrane (most commonly X-linked)
How does Alport syndrome present?
eye problems (e.g. retinopathy, lens dislocation), glomerulonephritis, and sensorineural deafness
Describe Type I membranoproliferative glomerulonephritis (MPGN)
tram track appearance on PAS stain and HE stain due to GBM splitting caused by mesnagial ingrowth (below)
due to subendothelial immune complex (IC) deposits with granular IF
What are some associations of Type I membranoproliferative glomerulonephritis (MPGN)
secondary to hep B or C (may also be idiopathic)
What are some associations of Type II membranoproliferative glomerulonephritis (MPGN)?
C3 nephritic factor (stabilizes C3 convertase and decreases serum C3 levels)
Describe the findings of nephrotic syndrome
massive proteinuria (3.5+g/day) with
hypoalbuminemia, resulting edema, hyperlipidemia
frothy urine with fatty casts
What causes nephrotic syndrome?
podocyte damage disrupting the gomerular filtration charge barrier
May be primary (direct sclerosis of podocytes) or 2ndary to a systemic process (e.g. diabetes)
Note that sever nephritic syndrome may present with nephrotic syndrome features if damage to the GBM if severe enough to damage the charge barrier (e.g. MPGN)
Nephrotic syndrome is associated with a hypercoaguable state. How?
due to loss of antirhrombin (AT) III in urine and increased risk of infection due to loss of immunoglobulins in urine and soft tissue compromise by edema
What disease present with nephrotic syndrome?
Focal segmental gomerulosclerosis
Minimal charge disease
Membranous nephropathy
Amyloidosis
Diabetic glomerulonephropathy
What dis?
focal segmental glomerulosclerosis LM showing segmental sclerosis and hyalinosis
What does focal segmental glomerulosclerosis IF show?
nonspecific for focal deposits of IgM, C3, and C1
What does focal segmental glomerulosclerosis EM show?
effacement of foot processes (similar to minimal change disease)
Describe focal segmental glomerulosclerosis
the most common cause of nephrotic syndrome in AAs and Hispanics. Can be primaru or 2ndary to other conditions (e.g. HIV, SCD, heroin abuse, massive obesity, interferon tx, or chronic kidney disease due to congenital malformations)
What is this EM showing?
Foot process effacement in Minimal change disease
Note the MCD has a normal LM and a negative IF
Describe minimal change disease
This is the most common cause of nephrotic syndrome in children. Often primary and may be triggered by recurrent infection, immunization, and immune stimulus
Minimal change disease may rarely be 2ndary to what?
lymphoma (e.g. cytokine-mediated damage)
Tx difference between Minimal change disease and focal segmental glomerulosclerosis
MCS has a great response to steroids, while FSG doesn’t
What is this?
Membranous nephropathy LM marked by diffuse capillary and GBM thickening
Buzzword EM of Membranous nephropathy
‘Spike and dome’ with subEPIthelial deposits
Describe Membranous nephropathy
most common cause of primary nephrotic syndrome in Causasian adults. Can be primary (idiopathic) or 2ndary to other conditions such as Abs to phospholipase A2 receptors, drugs, and infections
primary disease has POOR reponse to steroids
What drugs have been shown to cause Membranous nephropathy?
NSAIDs, penacillamine
What infections have been shown to cause Membranous nephropathy?
HBV
HCV
SLE
solid tumors
What would a positive LM of amyloidosis show?
apple-green birefringence under polarized light
What is the most commonly affected organ in amyloidosis?
the kidneys