Renal Pathology Flashcards
What are the different types of casts?
- CELLULAR casts - e.g. epithelial, RBC, WBC
- GRANULAR casts - breakdown of cellular casts
- HYALINE casts
- FATTY casts
Where are cellular casts formed?
Within the tubular lumen
What are casts primarily composed of?
Tamm-Horsfall protein - secreted from the renal tubular cells
What do hyaline casts indicate?
Usually nothing, tend to be of little diagnostic significance. May be seen in volume depleted states
From what are granular casts derived?
The breakdown of cellular casts, especially epithelial cell casts
What do epithelial cell casts indicate?
- Acute tubular necrosis
- Heavy metal poisoning
- Acute rejection of the transplant graft
What do RBC casts indicate?
- Glomerulonephritis
- IgA nephropathy
- Post streptococcal glomerulonephritis
- Goodpasture syndrome
- Malignant HTN
- Vasculitis
- Renal ischaemia
What do WBC casts indicate?
- Pyelonephritis
- Interstitial nephritis
- Lupus nephritis
What do granular casts indicate?
- Acute tubular necrosis
- Chronic renal failure
- Nephrotic syndrome
What do fatty casts indicate?
Nephrotic syndrome
What is the structure of fatty casts?
Maltese-cross configuration of cholesterol
What are the different types of glomerular disease?
- Nephrotic syndromes
2. Nephritic syndromes
What causes nephrotic syndrome?
Increased filtration barrier permeability
What are the nephrotic syndromes?
- MCD
- Focal segmental glomerulosclerosis
- Membranous glomerulopathy
- Membranoproliferative glomerulonephritis
- Diabetic nephropathy
- Renal amyloidosis
- Lupus nephritis
What causes nephritic syndrome?
Inflammatory damage to the glomeruli
What are the nephritic syndromes?
- Acute proliferative glomerulonephritis
- RPGN
- Anti-GBM disease
- Goodpasture syndrome
- IgA nephropathy (Berger disease)
- Alport syndrome (hereditary nephritis)
- Lupus nephritis
What are the characteristic symptoms of nephrotic syndrome?
Puffiness around the eyes
Pitting edema of the legs
Pleural effusion
Ascites
What are the hallmarks/signs of nephrotic syndrome?
Proteinuria Hypoalbuminaemia Edema Hyperlipidaemia Urinary fatty casts Hyper-coagulation
Why is there an increase in the permeability of the filtration barrier?
Mononuclear cells release cytokines.
These cytokines cause podocyte fusion + obliterate the -ve charge of the GBM
What is the definition of the proteinuria?
Urinary protein >3.5g/24hrs
What is the definition of hypoalbuminaemia?
Plasma albumin <3g/dL
What is the physiology of the edema in nephrotic syndrome?
Albumin loss = lower oncotic pressure
Lower oncotic pressure = loss of fluid from the circulation into the interstitial space
= activation of RAAS, increased sympathetic activity, release of vasopressin, decreased ANP release
All these changes^ = increased electrolyte and water retention
Why does hyperlipidaemia occur in nephrotic syndrome?
Increased production of lipoproteins by the liver in order to attempt to main the falling oncotic pressure in nephrotic syndrome
Why does hypercoaguability occur in nephrotic syndrome?
Loss of antithrombin III from the damaged glomeruli
= increased risk of renal vein thrombosis
What is the most common cause of nephrotic syndrome?
MCD
How is MCD diagnosed?
Renal biopsy + microscopy (specifically electron microscopy)
When is a definitive diagnosis not required for MCD?
Children with a typical presentation of MCD may be given an empiric steroids without a renal biopsy
What is seen on an electron microscope in MCD?
Effacement (fusion) of the visceral epithelial foot processes
What is seen on a light microscope in MCD?
Lipoid nephrosis - lipoid appearance of cells in proximal tubules
How is MCD treated?
High dose oral glucocorticoids (prednisolone). Alkylating agents (e.g. cyclophosphamide or chlorambucil) in failure to respond to steroids
What is the prognosis of MCD in an adult vs. children?
Adult = 50% response Children = 90% response to treatment
What proportion of cases of nephrotic syndromes does focal segmental glomerulosclerosis account for?
1/3 in adults; 50% of cases in African Americans
What is the most common glomerular disease in HIV patients?
Focal segmental glomerulosclerosis (FSGS)
What are the differences in presentation between FSGS and MCD?
FSGS = non-selective proteinuria (whereas MCD = selective proteinuria of albumin)
Patients with FSGS also have HTN and mild haematuria on top of the usual symptoms of nephrotic syndrome
What is seen on light microscopy in FSGS?
FOCAL accumulation of hyaline material
SEGMENTAL sclerosis
What is the prognosis of FSGS?
Poor - 50% develop ESRD within 10 years
What is the leading cause of nephrotic syndrome in adults?
Membranous glomerulopathy (30-40% of cases)
What are the demographics of membranous glomerulopathy?
More often seen in men - 2:1 ratio
Peak incidence = 30-50y/o
Is the proteinuria in membranous glomerulopathy selective or non-selective?
Non-selective
What systematic diseases are glomerulopathy associated with?
SLE RA Hep B Hep C Syphillis Schistomiasis Malaria Leprosy Drugs - e.g. gold and penicillamine
How do sub-epithelial deposits appear under the electron microscope?
‘Spike’ = extensions of GBM around the deposits + ‘Dome’ = deposits in the GBM
How is membranous glomerulopathy USUALLY treated? How otherwise might it be treated?
High rate of spontaneous remission, therefore no treatment needed. Otherwise, in severe disease, immunosuppressive therapy of cyclophosphamide + cyclosporine + glucocorticoids = used
What are the 2 types of membranoproliferative glomerulonephritis?
Type I - 2/3 of cases - type III hypersensitivity, deposition of immune complexes
type II - 1/3 of cases - associated with C3 nephritic factor. C£ present, but no IgG deposits
How does type I membranoproliferative glomerulonephritis appear under the electron microscope?
Subendothelial deposits of IgG + C3 + tram-track appearance from mesangium ingrowth into the GBM
How does type II membranoproliferative glomerulonephritis appear under the electron microscope?
Intramembranous deposits + increased glomeruli size + tram-track appearance
In whom with membranoproliferative glomerulonephritis may PE be useful?
In patients with circulating C3NeF
How does the prognosis differ between type I and II membranoproliferative glomerulonephritis?
Type I = 70-85% = no chronic decline in GFR
Type II = worse prognosis. Majority of patients progress to ESRD after 5-10 years
In which type of DM is diabetic nephropathy more common?
Type I
After how long of microalbuminaemia do other symptoms develop?
5-10 years
What is the leading cause of ESRD in the West?
Diabetic nephropathy
What is a complication seen in DM nephropathy?
Arteriosclerosis of the real artery
What is seen under the light microscope in DM nephropathy?
Thickening of GBM
Expansion of the mesangium
Kimmelstiel-Wilson lesions
How should DM nephropathy be treated?
Good glucose control + ACE inhibitors at onset of microalbuminaemia
What are the characteristics of amyloidosis?
Fibrous, insoluble proteins in a beta-pleated sheet confirmation in the extracellular space of the organs. = a multi-system disorder
What are the different types of amyloidosis that affect the kidney?
- Amyloid L (AL)
2. Amyloid A (AA)
What happens if the chains are not beta-pleated? What is the disease called then?
Light-chain deposition disease
From where may a biopsy be taken for diagnosis of amyloidosis?
Renal, abdominal fat pad, rectally
Which stain is used to identify amyloidosis? What is seen upon the staining being +ve?
Congo red stain will show apple-green bifringence in amyloidosis
How is amyloidosis treated?
Melphalan + prednisone
What are the classes of lupus nephritis?
I - no evidence of disease II - mesangial involvement III - focal proliferative nephritis IV - diffuse proliferative nephritis V - membranous nephritis
How is each class of lupus nephritis treated?
I - general SLE treatment II - corticosteroids III - high doses of corticosteroids IV - corticosteroids + immunosuppressants V - attend to general symptoms
What are the hallmarks of nephritic syndrome?
Haematuria
Oliguria
Azotemia
HTN
What is azotemia?
Increased blood urea nitrogen (BUN) and creatine
How do the symptoms of nephritic syndrome come about?
Haematuria = due to destruction of glomerular capillaries Oliguria = obstruction of glomerular capillary lumen decreases the GFR leading to oliguria (<400ml/day) and azotemia HTN = secondary to the increased fluid retention by the kidney due to decreased GFR
Which type of nephritic syndrome is most likely to affect children?
Acute proliferative glomerulonephritis (poststreptococcal)
After what does acute proliferative glomerulonephritis usually occur?
2-3 weeks after either pharyngeal or skin infections with GABHS