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Which are more common, primary or secondary renal diseases?
Secondary
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What is a predominately biochemical abnormality defined by elevated urea nitrogen and creatinine? By itself, this is not necessarily associated with significant clinical symptoms or problems.
Azotemia
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What is a symptom complex, associated with impaired renal function, that can include altered mental status, GI symptoms, pericardial effusion, and others? It is usually caused by significant, sustained renal impairment.
Uremia
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Both azotemia and uremia are associated with elevated BUN and creatinine. What is the difference?
Uremia is also associated with other clinical symptoms
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What syndrome is associated with inflammation in the glomerulus? It has an active urinary sediment: hematuria with dysmorphic RBCs and RBC casts. Proteinuria is present. There is a decrease in GFR, resulting in salt and fluid retention -- this often results in edema and hypertension. There will also be an increase in the serum creatinine. Azotemia is also seen.
Acute Nephritic Syndrome
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What is the acute nephritic syndrome usually caused by?
Acute Glomerulonephritis
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What syndrome has an active urinary sediment: hematuria with dysmorphic RBCs and RBC casts, as well as a rapid decline in renal function -- >50% decrease in GFR within 3 months? There are multiple different causes of this, and most are associated with crescents on renal biopsy.
Rapidly Progressive Glomerulonephritis (RPGN)
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What syndrome is associated with edema, marked proteinuria (> 3.5 grams protein per 1.73 m2 surface area per day), hypoalbuminemia ( < 3 grams/dL), hypercholesterolemia, lipiduria with oval fat bodies, and relatively inactive urinary sediment?
Nephrotic Syndrome
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What is the term used when only some of the glomeruli are affected in Glomerular Disease ( < 50%)?
Focal
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What is the term used when most or all glomeruli are affected in glomerular disease ( > 50%)?
Diffuse
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What is the term used when just part of the glomerulus is involved in glomerular disease?
Segmental
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What is the term used when the entire glomerulus is involved in glomerular disease?
Global
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Intracapillary proliferation indicates cells accumulating within the glomerular capillaries. What is this most commonly associated with?
Acute Glomerulonephritis
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Extracapillary proliferation indicates accumulation of cells in Bowman's space, outside of the glomerular capillary tuft -- typically called a crescent. What is this a marker of?
It usually results from ruptures in the glomerular capillary basement membrane, with leakage of fibrin into Bowman's space. The leakage is believed to stimulate the proliferation of the parietal epithelial cells and recruitment of monocytes, resulting in the accumulation of crescent cells in Bowman's space. This often results in what clinical picture?
- Marker of severe glomerular injury
- Rapidly Progressive Glomerulonephritis (RPGN)
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What is the most common metabolic disease causing glomerular disease?
Diabetes Mellitus
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What two types of infections are most commonly associated with glomerular diseases?
Bacterial and Viral (streptococcus pyogenes; staphylococcus aureus; Hepatitis B & C)
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In general, ___________ glomerular deposits are associated with inflammation; usually intracapillary proliferation, and tend to be more damaging to the glomerulus; they manifest as the nephritic syndrome with hematuria, etc.
Subendothelial Deposits
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____________ glomerular deposits tend to be associated with damage to the visceral epithelial cell foot processes; they are usually not associated with significant inflammation or much increase in glomerular cellularity; they usually manifest clinically as proteinuria.
Subepithelial Deposits
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___________ glomerular deposits aer usually assoicated with increased mesangial cellularity (sometimes with focal segmental intracapillary proliferation); they tend to present clinically as hematuria, but usually not with marked acute decrease in renal function.
Mesangial Deposits
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Antibodies to the glomerular basement membrane are often associated with what? They are also associated with hematuria and often a rapid decline in renal function. They are one cause of the picture of rapidly progressive glomerulonephritis (RPGN).
Severe glomerular injury with crescents in Bowman's space
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What diseases are associated with GBM antigens? What does the immunofluorescence look like?
- Anti-GBM Nephritis
- Linear Capillary Wall
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What diseases are associated with subepithelial glomerular localization of immune complexes (between podocytes and GBM)? What does the immunofluorescence look like?
- Membranous Glomerulonephritis & Post-infectious Glomerulonephritis
- Granular Capillary Wall
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What diseases are associated with subendothelial glomerular localization of immune complexes (between GBM and endothelium)? What does the immunofluorescence look like?
- Membranoproliferative Glomerulonephritis & SLE
- Granular Capillary Wall
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What disease is associated with mesangial glomerular localization of immune complexes? What does the immunofluorescence look like?
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Which type of antibodies are very damaging, and associated with crescentic GN?
Antibodies to intrinsic GBM
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Which type of deposits are exposed to the circulation; they activate complement, and elicit an inflammatory response (leukocytes)?
Subendothelial Deposits
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Which type of glomerular deposits is associated with injury to foot processes? There is little inflammation.
Subepithelial Deposits
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Which type of glomerular deposits is associated with variable inflammation -- often mesangial or focal and segmental?
Mesangial Deposits
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What is the clinical presentation of GBM antigens?
RPGN
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What is the clinical presentation associated with subendothelial glomerular deposits?
Nephritic Picture
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What is the clinical presentation associated with subepithelial glomerular deposits?
Proteinuria or Nephrotic Syndrome
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What is the clinical presentation associated with mesangial glomerular deposits?
Hematuria
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Acute Nephritic Syndrome is associated with what three disesase types?
- Post-Infectious GN
- Membranoproliferative GN (MPGN)
- Lupus Nephritis
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Rapidly Progressive Glomerulonephritis is associated with what three disease types?
- Anti-GBM Disease
- ANCA-associated GN
- Immune Complex GN (severe)
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Nephrotic Syndrome is associated with what six disease types?
- Minimal Change Disease
- Focal Segmental Glomerulosclerosis (FSGS)
- Membranous Nephropathy
- Membranoproliferative GN (MPGN)
- Diabetic Nephropathy
- Amyloid
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Asymptomatic Hematuria is associated with what three disease types?
- IgA Nephropathy
- Alport Syndrome
- Thin GBM Nephropathy
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Group A beta-hemolytic Streptococcal pharyngitis was formerly the most common cause of Post-Infectious Glomerulonephritis in the US, with strep skin infections being a common cause in the tropics. What are the two most common causes in the US today?
Streptococcus & Staph. aureus
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Identify the syndrome:
Usually affects children or young adults
Occurs ~1-2 weeks following an infection with pharyngitis
Abrupt onset of "smokey" urine, edema, hypertension, plus or minus oliguria
Urinalysis: hematuria, RBC casts
Elevated antibodies against streptolysin O (ASO), DNase-B
Low serum complement levels
Light Microscopy: diffuse proliferative intracapillary glomerulonephritis
Increased cellularity within capillary tufts, filling capillary lumens
Neutrophils often present
Severe Cases: may have crescents in Bowman's space (extracapillary proliferation)
Post-Streptococcal Acute Glomerulonephritis
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Identify the pathology below:
- Acute Post-Streptococcal Glomerulonephritis
- Cellularity within the capillary tuft is greatly increased; there are numerous neutrophils present (the smaller, dark dots). The lumens of the glomerular capillaries are occluded by the inflammatory cells, and probably also by swelling of the endothelial cells. The entire glomerulus is involved.
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Identify the pathology below:
- Acute Post-Infectious Glomerulonephritis
- Deposits of IgG and C3 in capillary walls; the pattern here is discrete, granular staining along the capillary wall. The deposits are relatively large
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Identify the pathology below:
- Acute Post-Infectious Glomerulonephritis
- Note large subepithelial deposits ("humps") located outside of GBM and under visceral epithelial cell (podocyte)
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What is the prognosis associated with Acute Post-Infectious Glomerulonephritis?
- Children: often spontaneously recover; good prognosis
- Adults: may have residual chronic renal insufficiency
- Other Infections: less favorable prognosis
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Identify the syndrome:
Heterogenous group of conditions with similar morphologic appearance
Many different causes
May present with nephrotic syndrome (50%), nephritic syndrome, or mixture
Activation of complement system critical in pathogenesis
There are two different types, type I (most common) and type II (aka dense deposit disease [likely not one of these but still called it])
Diffuse and global increased cellularity in glomerular capillary tuft
Appearance of reduplication of GBM ("tram track" appearance): interposition of mesangial cells and matrix under endothelium; new basement membrane deposition forming double layer (key feature)
Membranoproliferative Glomerulonephritis (MPGN)
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Many adult cases of Membranoproliferative Glomerulonephritis (MPGN) are associated with what? Pediatric cases are often idiopathic.
- Hepatitis C Virus (big one)
- Cryoglobulinemia
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Identify the pathology below:
- Membranoproliferative Glomerulonephritis (MPGN)
- The glomerulus has an exaggerated lobular appearance; the individual lobes stand out much more than in normal glomeruli. The lumens of the glomerular capillaries appear occluded. There is an increase in cells in the glomerulus, but it is hard to make that out in this pic.
-
Identify the pathology below:
- Membranoproliferative Glomerulonephritis (MPGN)
- There are two layers of the GBM (reduplication or "tram track"). There are cells and matrix between the two layers of GBM.
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Identify the pathology below:
- Membranoproliferative Glomerulonephritis
- Granular capillary wall deposits; sometimes they are so dense that the staining appears linear rather than granular (as at the top of the photo), but it is clearly granular in other areas (toward the bottom).
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Identify the pathology below:
- Membranoproliferative Glomerulonephritis
- Subendothelial deposits; cellular and matrix interposition under endothelium; new layer of GBM -- like material under interposed cells
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What is the clinical course associated with Membranoproliferative Glomerulonephritis? How is it treated?
- 1/3 -- remission; 1/3 -- slow progression to chronic renal insufficiency; 1/3 -- waxes and wanes, but never disappears
- Treat underlying cause, if any; immunosuppressants sometimes used on idiopathic variants
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Identify the syndrome:
Form of Membranoproliferative Glomerulonephritis
Rare
Activation of alternate pathway of complement activation: C3 Nephritic Factor -- antibody binds to and prevents inactivation of C3 convertase; prolonged activation of alternate pathway of complement
Characteristic Feature: dense linear deposits within thicked GBM
Cause unknown
Clinical course: inexorable progression to renal insufficiency
No established treatment
Dense Deposit Disease (MPGN Type II)
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Identify the pathology below:
- Dense Deposit Disease (MPGN Type II)
- The very dense deposits aer deposited within the thickened GBM -- not beneath it, as in MPGN Type I.
-
Identify the syndrome:
Clinicopathologic sydnrome associated with severe glomerular injury: nephritic syndrome with >50% loss of renal function within 3 months
Multiple causes
Associated with crescents in Bowman's space (>50% of glomeruli have crescents)
Rupture of GBM, with leakage of fibrin into urinary space: stimulates the formation of the crescents
Rapidly Progressive Glomerulonephritis (RPGN)
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Identify the pathology below:
- Rapidly Progressive Glomerulonephritis
- This shows a glomerulus with a large crescent (proliferation in Bowman's space, on the left) compressing the glomerular capillary tuft. The black wrinkled structure in the middle is part of the glomerular capillary basement membrane, which has collapsed due to severe damage; there are a few residual, relatively normal looking capillary loops on the right side of the glomerulus.
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Identify the pathology below:
- Rapidly Progressive Glomerulonephritis (RPGN)
- The crescent is at the top of the glomerulus. On the left are disruptions in the glomerular capillary basement membrane. On the right is darker pinker material, which probably represents fibrin. It is believed that fibrin leaking from Bowman's space elicits the cellular reaction that makes up the crescent
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What is the most common variant of Crescentic Glomerulonephritis (RPGN)? What are the other two?
- ANCA-associated Glomerulonephritis (~60%) -- Wegener's Granulomatosis; Microscopic Polyangiitis
- Anti-GBM Disease (~15%)
- Immune Complex Type (~25%) -- usually infectious
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Anti-GBM Disease occurs when there is an antibody directed against the intrinsic GBM antigen, usually part of collagen IV. This is often associated with pulmonary hemorrhage. What disease occurs when the anti-GBM antibody cases glomerulonephritis AND pulmonary hemorrhage?
Goodpasture Syndrome
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Identify the pathology seen below:
- Anti-GBM Disease
- The pattern is smooth, linear and intense, demonstrating the presence of IgG distributed evenly along the length of the glomerular capillary basement membrane. This is really the diagnostic feature of anti-GBM disease
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Death in the acute phase of anti-GBM disease is usually due to what, rather than the renal disease?
Pulmonary hemorrhage -- drown by bleeding into own lungs
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Untreated anti-GBM disease is rapidly fatal. What does treatment consist of?
- Plasmapheresis
- Corticosteroids
- Cyclophosphamide
-
Identify the syndrome:
This is the most common cause of RPGN
Often associated with systemic vasculitis: Wegener's granulomatosis & microscopic polyangiitis
May be renal-limited: no systemic disease
Usually "pauci-immune": scant or absent findings on immunofluorescence
Light Microscopy: segmental necrosis in capillary tuft; crescents in majority of glomeruli; may have vasculitis in renal vessels (rare)
Electron Microscopy: rupture of GBM; no immune complex deposits
ANCA-associated RPGN
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There are two variants of ANCA. What are they, and what form of vasculitis is each associated with?
- PR3-ANCA (C-ANCA): associated with Wegener's
- MPO-ANCA (P-ANCA): associated with microscopic polyangiitis and other forms of vasculitis
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What is the most common cause of nephrotic syndrome overall?
Diabetes
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What are the two most common causes of nephrotic syndrome in children?
- Minimal Change Disease (most common)
- Focal Segmental Glomerulosclerosis (FSGS) (second)
-
What are the two most common causes of nephrotic syndrome in adults?
- Focal Segmental Glomerulosclerosis (now most common)
- Membranous Nephropathy (used to be most common)
-
What is the most common cause of nephrotic syndrome in African-Americans?
Focal Segmental Glomerulosclerosis (FSGS)
-
Identify the syndrome:
Most common cause of nephrotic syndrome in childhood. (less common in adults)
Cause of majority of cases unknown: possible circulating factor which damages visceral epithelial cells
May be secondary, particularly in adults
Light Microscopy: essentially normal glomeruli
Immunofluorescence: negative (usually)
Electron Microscopy: diffuse effacement of visceral epithelial cell foot processes -- appears to be a continuous layer; loss of discrete foot processes; no immune complex deposits present
Primary treatment is corticosteroids
Prognosis is good in children; less favorable in adults
Minimal Change Disease
-
Identify the pathology below:
- Minimal Change Disease
- Note the effacement of the foot processes -- there is an apparently continuous layer of visceral epithelial cell cytoplasm covering the GBM, rather than the normal discrete foot processes
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What is the primary treatment for Minimal Change Disease? What is the prognosis in children? Adults?
- Corticosteroids
- Children: good; may have relapses of nephrotic syndrome; renal function is usually preserved
- Adults: response less reliable; prognosis less favorable
-
Identify the syndrome:
Clinicopathological syndrome -- not a specific disease
Multiple possible causes
Most common presentation is the nephrotic syndrome
Elevated creatinine and hypertension are more common than in some other diseases
More common in african-americans than in causcasians
There appears to be a loss of the charge selectivity of the glomerular filtration barrier -- the foot processes lose the normal net negative charge which helps prevent negatively-charged substances from being filtered
Light Microscopy: segmental sclerosis involving a minority of glomeruli
Immunofluorescence: plus/minus IgM and C3 (nonspecific)
Electron Microscopy: foot process effacement in all glomeruli; segmental collapse and sclerosis of the capillary loops
No immune complex deposits present
When untreated, this results in progressive proteinuria and declining renal function
Corticosteroids are often used; some respond
Cyclophosphamide, cyclosporine also used
Focal Segmental Glomerulosclerosis (FSGS)
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Identify the pathology below:
- Focal Segmental Glomerulosclerosis
- The area in the lower left shows obliteration of the capillary lumens with replacement of sclerosis; the remainder of the glomerulus looks normal
-
What is the treatment for Focal Segmental Glomerulosclerosis?
- Corticosteroids
- Cyclosphosphamide, Cyclosporine also used
-
Identify the syndrome:
Clinicopathologic syndrome with characteristic pathologic appearance
Main finding: subepithelial immune deposits
Most common primary renal cause of nephrotic sydrome in adults (was in past, anyway)
Less common in children
Majority of cases are idiopathic
Light Microscopy: thickening of GBM, plus/minus GBM "spikes"
Immunofluorescence: granular capillary wall staining for immunoglobulins (usually IgG) plus/minus C3
Electron Microscopy: subepithelial deposits along entire GBM; plus/minus GBM spike formation with thickening of GBM; deposits may be incorporated into thickened GBM
Outcome is variable
Membranous Nephropathy
-
Identify the pathology below:
- Membranous Nephropathy
- On the light microscopy (top), note the thick, rigid-appearing capillary basement membranes
- On the immunoflluorescence (bottom), note the granular deposits covering all the capillary loops
-
Identify the pathology below:
- Membranous Nephropathy
- Shows GBM "spikes", which are new growths of the GBM sticking up around the deposits. The apparent holes in the GBM are places where the deposits are sitting (the deposits themselves don't show up with this stain)
-
Identify the pathology below:
- Membranous Nephropathy
- Note that the visceral epithelial cell foot processes appear simplified or effaced and lack the normal interdigitating foot processes
-
What is the most common outcome for people with Membranous Nephropathy?
- The disease tends to have remissions and relapses, or the people have persistent proteinuria but renal function is relatively preserved
- Overall renal survival ~60% at 15 years
-
What is the standard therapy for primary membranous nephropathy (treat underlying disease in secondary)?
- Corticosteroids, with or without cyclophosphamide
- Reduction of proteinuria with ACE inhibitors & angiotensin receptor blockers is also standard
-
What are three glomerular diseases that present with asymptomatic hematuria?
- IgA Nephropathy (Berger's Disease)
- Alport Syndrome
- Thin Basement Membrane Nephropathy
-
What is the most common type of primary glomerulonephritis worldwide?
IgA Nephropathy (IgAN)
-
Identify the syndrome:
Considered a glomerulonephritis because the glomeruli typically have increased cellularity. However, patients are often asymptomatic except for hematuria (not full nephrotic syndrome)
Characteristic Feature: IgA deposits in mesangium as sole or dominant immunoglobulin; C3 also common
Limited to the kidney
Cause not totally understood
IgA deposits appear derived from circulation
Abnormality in hinge region of IgA molecules may result in defective clearance from circulation, which may result in deposition in mesangium
Light Microscopy: variable (most common: mesangial proliferation GN)
Typical presentation is hematuria
Half of patients: macroscopic hematuria associated with upper respiratory tract infection
Clinical course is variable
Common cause of glomerulonephritis resulting in end-stage renal disease
No specific treatment
IgA Nephropathy
-
What is a clinical syndrome characterized by systemic vasculitis; manifestations include abdominal pain, arthritis, glomerulonephritis, and often a skin rash? In the kidney, the immunofluorescence pattern is identicle to IgA nephropathy (but IgA nephropathy is limited to the kidney). This is most common in children aged 3-8 years (excellent prognosis); also occurs in adults (less favorable). It often follows an upper respiratory tract infection. Cases that have crescents on biopsy tend to have a more aggressive course, with a higher risk of progression to renal failure
Henoch-Schonlein Purpura (HSP)
-
Identify the pathology below:
- IgA Nephropathy
- "Pruned bush" appearance. The glomerular capillaries are not staining; do not see the loops and circles that you see in membranous nephropathy or MPGN
-
Identify the pathology below:
- IgA Nephropathy
- There are immune deposits (dark) located in the mesangium, predominantly just beneath the basement membrane overlying the mesangium. There are usually no subendothelial or subepithelial deposist in IgA nephropathy
-
Identify the syndrome:
Hereditary nephritis: mutation in type IV collagen
May be associated with hearing loss and eye disorders
Usually presents as hematuria (gross or microscopic) plus/minus proteinuria
Onset usually ~5-20 years
Progression to renal failure by 20-50 years
Majority of cases are X-linked
Hearing disorders are variable; may be subtle or absent
Light microscopy varies with disease course (normal --> focal sclerosis --> global glomerulosclerosis
Characteristic GBM findings in EM: irregular thickening and thinning; splitting and lamination of lamina densa -- "basket weave" appearance)
Alport Syndrome
-
Identify the pathology below:
- Alport Syndrome
- Irregular thickness and a pale, loose appearance with a suggestion of multiple lamellations ("basket weave" appearance)
-
Identify the syndrome:
Hereditary Condition -- mutation in a type IV collagen subunit
Autosomal Dominance inheritance
Pathology: unusually thin GBMs on EM (normal by light microscopy and immunofluorescence
Present with asymptomatic hematuria
Clinical course usually benign (renal function preserved)
Thin Basement Membrane Nephropathy
-
Identify the syndrome:
The end stage of many different types of glomerular diseases
Morphology: global glomerulosclerosis involving majority of glomeruli
May be difficult to determine what the primary glomerular disease was
Results in end-stage renal disease
Can be caused by poststreptococcal GN, crescentic GN, membranous nephropathy, focal segmental glomerulosclerosis, membranoproliferative GN, IgAN
Chronic Glomerulonephritis
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