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Arjun's PM copy-Histopathology > Histo: Renal Disease > Flashcards

Histo: Renal Disease Flashcards

1
Q

List the major functions of the kidneys.

A
  • Excretion of metabolic waste products and foreign chemicals
  • Regulation of fluid, electrolytes and acid/base balance
  • Regulation of blood pressure (renin)
  • Regulation of calcium and bone metabolism (1,25-dihydroxy vitamin D)
  • Regulation of haematocrit (EPO)
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2
Q

List some key anatomical features of the kidneys.

A
  • Retroperitoneal
  • T12-L3
  • Right kidney lies lower
  • Mean length = 11cm
  • Normal weight = 115-170g
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3
Q

What proportion of cardiac output goes to the kidneys?

A

20%

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4
Q

By what mechanism is blood filtered through the glomerulus?

A
  • High hydrostatic pressure (60 mmHg)
  • Podocytes create a charge-dependent (anionic) and size-dependent barrier
  • Filtration rate = 125 ml/min
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5
Q

Describe the role of the
proximal convoluted tubule.

A
  1. Proximal convoluted tubule(main place for reabsorption -e.g. all glucose etc…)
    • Actively absorbs sodium
    • Carries out hydrogen exchange to allow carbonate resoprtion
    • Co-transport of amino acids, phosphate and glucose
    • Reabsorption of potassium
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6
Q

Describe the role of the loop of Henle.

A

Loop of Henle

  • Descending limb and thin ascending limb: permeable to water, impermeable to ions and urea
  • Ascending limb: actively resorbs sodium and chloride (just think Salt- main thing for countercurrent multiplier)
  • This creates a counter-current multiplier that is aligned with the vasa recta
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7
Q

Describe the role of the distal convoluted tubule.

A

Distal convoluted tubule

  • Impermeable to water
  • Regulates pH by active transport of protons and bicarbonate
  • Regulates sodium and potassium by active transport (aldosterone)
  • Regulates calcium (PTH, 1,25-dihydroxy vit D)
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8
Q

Describe the role of the collecting duct.

A

Collecting duct

  • Reabsorb water (principal cells, ADH)
  • Regulates pH (intercalated cells, proton excretion)

(Would be too easy if principal and pH)

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9
Q

Describe how disease of the kidney can be classified according to the part of the nephron it affects

A

1. Glomerulus

Nephrotic:

  • Primary = MCD, FSGS, MGD
  • Secondary = diabetes, amyloidosis, SLE

Nephritic:

  • Acute post-infectious (post-streptococcal)
  • IgA nephropathy (Berger Disease)
  • Rapidly progressive glomerulonephritis
  • Alport’s syndrome (hereditary nephritis)
  • Thin basement membrane disease (Benign familial haematuria)

2. Tubules & interstitium

  • Acute tubular necrosis
  • Tubulointerstitial nephritis

3. Blood vessels

  • Thrombotic microangiopathies (HUS, TTP)
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10
Q

Describe how immune complex deposition can lead to renal disease.

A

Complex deposition in the glomerulus results in complement and inflammatory cell activation resulting in damage to the kidney

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11
Q

List some genitourinary malformations of the kidney.

A
  • Agenesis
  • Renal fusion (horshoe?)
  • Ectopic kidney
  • Renal dysplasia
  • PUJ obstruction
  • Posterior urethral valve (can back up- hydronephrosis)
  • Vesicoureteric reflux
  • Ureteral duplication (duplex collecting system ie. 2 ureters draining kidney)
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12
Q

Outline the presentation of polycystic kidney disease.

A
  • Hypertension
  • Haematuria
  • Flank pain

Adult onset i think in ADPKD
(ARPKD has kidney failure in late childhood)

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13
Q

What is the inheritance pattern of polycystic kidney disease and which genes are implicated?

A

Autosomal dominant (most of the time)

Genes: PKD1 and PKD2 (hence type 1 (chrom 16) (more common and serious ie presents earlier) and 2 (chrom 4))

NOTE: PKD is associated with an increased risk of berry aneurysms (and subarachnoid haemorrhage), and other aneurysms eg liver, spleen, pancreas (I think liver is more common than berry aneurysms)

US scan to diagnose

Treat with Tolvaptan (to slow down progress of cysts)

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14
Q

In which group of renal patients do renal cysts often develop?
What do they increase the risk of?

A
  • Patients with end-stage renal disease who are on dialysis ie acquired renal cysts
  • Cysts are often multiple, bilateral and cortical and medullary

NOTE: cystic disease is associated with increased risk of malignancy (papillary renal cell carcinoma)

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15
Q

What is Alport syndrome?

A

Genetic condition affecting type IV collagen (Alport and type 4). Leads to triad of:

  • Kidney disease
  • Hearing loss (SNHL)
  • Eye changes (lenticonus, cataracts)
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16
Q

List some causes of acute renal failure.

A
  • Pre-renal = failure of perfusion (shock, heart failure)
  • Renal = ATN, acute glomerulonephritis, thrombotic microangiopathy
  • Post-renal = obstruction to urine flow
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17
Q

What is the most common cause of acute renal failure?

A

Reduced renal perfusion

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18
Q

List some causes of acute tubular injury.

A
  • Ischaemia
  • Toxins - contrast, haemoglobin, myoglobin, ethylene glycol (antifreeze), drugs (DAAAMN))
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19
Q

Which commonly used class of drugs predisposes to acute tubular injury?

A

NSAIDs - inhibits vasodilatory prostaglandins which predisposes to ATN

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20
Q

How does acute tubular injury lead to reduced GFR?

A
  • Blockage of tubules by casts
  • Leakage from tubules into interstitial space
  • Secondary haemodynamic changes
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21
Q

Describe the histological appearance of ATN

A

Necrosis of short segments of tubules

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22
Q

What is acute tubulo-interstitial nephritis?

A

Inflammation of the renal interstitium, typically due to immune-mediated hypersensitivity reaction

Can be caused by infection and drugs (NSAIDs, antibiotics, diuretics, allopurinol, PPIs)

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23
Q

Describe the histological appearance of acute tubulo-interstital nephritis.

A

Heavy interstitial infiltration with eosinophil and granulomas

Interstitial nephritis, also known as tubulointerstitial nephritis, is inflammation of the area of the kidney known as the renal interstitium, which consists of a collection of cells, extracellular matrix, and fluid surrounding the renal tubules. It is also known as intestinal nephritis because the clinical picture may include mesenteric lymphadenitis in some cases of acute pyelonephritis (mostly due to use of NSAIDs)

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24
Q

What are some key signs of acute glomerulonephritis?

A
  • Oligo/anuria
  • Haematuria
  • Erythrocyte and leukocyte casts on MCS
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25
What is rapidly progressive (crescentic) GN?
Most aggressive form of GN – can cause ESRF within weeks. Presents as a nephritic syndrome, but oliguria and renal failure are more pronounced
26
What causes crescents to appear in acute glomerulonephritis?
Occurs in severe glomerulonephritis due to proliferation of macrophages & parietal cells in Bowman’s space which pushes glomerulus to one side
27
Describe the classification of acute crescentic glomerulonephritis.
*Classification based on immunological findings:* - Type 1. Anti-GBM antibody (Goodpasture's) - Type 2. Immune complex mediated (SLE) - Type 3. Pauci-immune (ANCA-associated - GPA) ## Footnote NOTE: these can rapidly lead to irreversible renal failure
28
List some causes of immune complex-associated (type 2) crescentic glomerulonephritis.
* SLE * IgA nephropathy * Post-infectious glomerulonephritis * HSP
29
What techniques can be used to visualise immune complexes in these diseases?
- Immunohistochemistry (fluorescence microscopy) - Electron (light) microscopy
30
How does immune complex-associated crescentic GN appear on fluorescence microscopy?
Granular (lumpy bumpy) IgG immune complex deposition on GBM/mesangium
31
What are the antibodies directed against in anti-GBM disease? How can these antibodies be detected?
- Against the **C-terminal domain of type IV collagen (COL4-A3)** - Detected by serology ## Footnote NOTE: these antibodies can cross-react with the alveolar basement membrane leading to pulmonary haemorrhage and haemoptysis
32
Describe the immunohistochemistry picture produced in anti-GBM disease
Linear deposition of IgG on the glomerular basement membrane
33
What are the main features of pauci-immune crescentic glomerulonephritis?
* Lack of / scanty glomerular immunoglobulin depositis * Usually associated with ANCA * Triggers neutrophil activation and glomerular necrosis * Vasculitis (elsewhere) – particularly presenting as skin rashes or pulmonary haemorrhage
34
What is thrombotic microangiopathy?
* Damage to the endothelium in glomeruli, arteriols and arteries resulting in thrombosis * Red cells can be damaged by fibrin causing MAHA or HUS
35
List some types of thrombotic microangiopathy.
**HUS:** *Thrombi confined to kidneys* - Typical HUS - usually associated with diarrhoea caused by E.coli O157:H7 (outbreaks caused by children visiting petting zoos/eating undercooked meat) - Atypical HUS (non-diarrhoea associated) - due to abnormal proteins in complement pathway/endothelium (can be familial) - **Triad** - thrombocytopaenia, MAHA, renal damage **TTP:** *Thrombi occur throughout circulation, esp. in CNS* - A genetic / acquired deficiency of ADAMTS13 - **Pentad** - thrombocytopaenia, MAHA, renal damage, CNS abnormalities, fever **Also:** - Drugs, radiation, hypertension, scleroderma, antiphospholipid syndrome
36
What are the characteristic features of nephrotic syndrome?
* Proteinuria (\>3.5 g/day or >300mg/mmol PCR) * Hypoalbuminaemia * Oedema * Hyperlipidaemia
37
List some causes of nephrotic syndrome.
* **Primary glomerular disease (non-immune complex mediated)** * Minimal change disease * Focal segmental glomerulosclerosis * **Primary renal disease (immune complex mediated)** * Membranous glomerulonephritis * **Systemic disease** * SLE * Amyloidosis * Diabetes mellitus
38
What is minimal change disease?
* Most common cause of nephrotic syndrome in **children** * Glomeruli look normal on light microscopy, but electron microscopy shows **loss of foot processes** * Generally responds well to steroids and immunosuppression
39
Describe the histological appearance of focal segmental glomerulosclerosis.
Focal and segmental glomerular consolidation and scarring Hyalinosis NOTE: this responds less well to immunosuppression
40
What is membranous glomerulonephritis?
* Common cause of nephrotic syndrome in adults * Characterised by immune deposits outside the glomerular basement membrane (**subepithelial - 'spikey')** * Primary disease is autoimmune * It can occur secondary to epithelial malignancy, SLE, drugs and infections
41
Which antibodies are often found in primary membranous glomerulonephritis?
Antibodies against **phospholipase A2 type M receptor (PLA2R)**
42
Describe the typical progression of diabetic nephropathy.
- Occurs in 30-40% diabetics - Typically begins with microalbuminuria - Progresses to proteinuria and, eventually, nephrotic syndrome
43
List and describe the stages of diabetic nephropathy.
* Stage 1: thickening of the basement membrane on electron microscopy * Stage 2: increase in mesangial matrix, without nodules * Stage 3: nodular lesions/Kimmelstein-Wilson nodules * Stage 4: advanced glomerulosclerosis
44
What is amyloidosis?
Deposition of extracellular proteinaceous material exhibiting beta-pleated sheet structure
45
What are the two types of amyloidosis?
* **AA** - derived from serum amyloid associated protein (SAA), an acute phase protein, and associated with **chronic inflammatory disease** * **AL** - derived from immunoglobulin light chains usually as a result of **multiple myeloma** (80%)
46
Describe the histological appearance of amyloidosis
Apple green birefringence with Congo red stain
47
Name two causes of isolated / asymptomatic microscopic haematuria.
* Thin basement membrane disease * IgA nephropathy
48
How can the cause of asymptomatic proteinuria be confirmed?
Renal biopsy for histology, IHC, and electron microscopy (could be caused by several abnormalities)
49
What is thin basement membrane disease and what causes it?
* Basement membrane \<250 nm thickness * Caused by a hereditary defect in type IV collagen synthesis * Microscopic haematuria is the only consequence in most cases
50
What is Alport syndrome? What is its inheritance pattern?
* **X-linked dominant** condition caused by a mutation in the alpha-5 subunit of type IV collagen (some forms affect alpha-3 and alpha-4) * Leads to progressive damage resulting in renal failure in middle-age * Often accompanied by **deafness and ocular disease**
51
What is IgA nephropathy?
* **Most common cause of glomerulonephritis** * Caused by mesangial IgA immune complex deposition * 30% will progress to end-stage renal failure * Presents 1-2 days after an URTI with frank haematuria (earlier than acute post-infectious GN) * Immunofluorescence shows **granular deposition** of IgA and C3 in mesangium ## Footnote NOTE: Henoch-Schonlein purpura is a type of IgA nephropathy
52
What is acute post-infectious (post-streptococcal) GN?
- Occurs 1-3 weeks after streptococcal throat infection or impetigo (usually Lancefield Group A α-haemolytic strep = Strep. pyogenes) - Glomerular damage thought to be due to immune complex deposition
53
What will a biopsy show in post-infectious GN?
- Light microscope: ↑cellularity of glomeruli - Fluorescence Microscope: granular deposits of IgG and C3 in GBM - Electron Microscope: Subendothelial humps
54
List some causes of chronic kidney disease and state which is most common.
* Diabetes mellitus (most common) - 27.5% * Glomerulonephritis - 14.1% * Polycystic kidney disease - 7.4% * Pyelonephritis - 6.5% * Hypertension - 6.8% * Renal vascular disease - 5.9%
55
What are some diseases associated with chronic kidney disease?
* Ischaemic heart disease * Calcium and phosphate derangement (due to resulting hyperparathyroidism, osteomalacia and osteoporosis)
56
What is the pathophysiology of hypertensive nephropathy?
- Narrowing of arteries and arterioles leading to scarring and ischaemia of glomeruli - Hypertension in glomeruli leading to altered haemodynamic environment, stress and segmental scarring
57
What are consequences of hypertensive nephropathy?
* **Shrunken kidneys with granular cortices** * **Nephrosclerosis** on histology - arterial hyalinosis, arterial intimal thickening, ischaemic glomerular changes, segmental and global glomerulosclerosis
58
What system is used to classify lupus nephritis?
ISN/RPS classification
59
Describe the histological appearance of lupus nephritis
- Immune complex deposition in capillaries > **‘wire loop capillaries’ (thickened)** - Deposition of immune complexes & complement in the GBM in a lumpy-bumpy granular fashion.
60
What are the outcomes of lupus nephritis?
Highly variable - Acute renal failure - Nephrotic syndrome - Isolated urinary abnormality - CKD Six stages: • 1: Minimal mesangial disease, almost normal • 2: Mesangial disease • 3: Focal deposits • 4: Diffuse deposits • 5: Subepithelial membranous disease • 6: Advanced sclerosis (>90%)

Arjun's PM copy-Histopathology (20 decks)

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