Renal Pathology

Question 1

Describe basic kidney anatomy and histology

Answer 1

• Renal corpuscule (glomerulus / bowmans capsule)

- PCT, loop of henle, DCT, collecting tubules

Question 2

List the different glomerular diseases

Answer 2

• Glomerulonephritis
• Pyelonephritis
• Acute Tubular Necrosis
• Kidney Stones
• Renal Cell Carcinoma
• Transitional Cell Carcinoma
• Polycystic Kidney Disease

Question 3

What is glomerulonephritis and list the types

Answer 3

• Inflammation of the glomerulus
• Immune related
• Antibody-antigen complexes build and become trapped (block filtration, tissue injury, long term complete / phagocyte activation), proteinuria
• Proliferation of messengial cells, entrapment of leukocytes, blockage of glomeruli, hematuria, edema
• Enlarged hyper-cellular glomeruli and humps of antigen-antibody complexes
• Types: Nephritic, nephrotic and cresentic

Question 4

What is nephrotic glomerulonephritis

Answer 4

• Minimal change disease
• Focal segmental glomerulosclerosis
• Membranous nephropathy and membranoproliferative glomerulonephritis
• Derangement of capillary walls / thin of foot processes
• Proteinuria, decreased serum albumin / oncotic pressure
• Increased edema, swelling in legs / ankles, fatigue, poor appetite, high lipids in urine, hypoalbuminemia
• Absence of immune deposits, immune dysfunction, damage to glomerulus, benign
• Resolves with corticosteroid therapy

Question 5

What is nephritic glomerulonephritis

Answer 5

• Acute post infectious (post-streptococcal)
• IgA nephropathy (Berger disease) and hereditary nephritis
• Inflammatory cells in glomeruli
• Type III HS reaction (1-2 w after sore throat or 6 w after skin infection)
• Acute onset of hematuria, oliguria, proteinuria, azotemia

Question 6

What is crescent glomerulonephritis

Answer 6

• Extensive glomerular crescents
• Proliferating cells in Bowmans capsule (histologic marker)
• Rapidly progressive
• Rupture of glomerular capillaries causes cellular and humoral inflammatory mediators to fill BC
• Rapid loss of renal function, glomerular injury

Question 7

What is acute pyelonephritis

Answer 7

• Kidney infection
• suppurative inflammation of kidney and pelvis
• Caused by E. coli
• Risk factors (female, UTO, catheterisation, vesicoureteral reflux)
• Complication of UTI (cystitis, prostatitis, urethritis)
• Bacteria reach kidney by haematogenous infection (septicaemia / endocarditis) or ascending UTI / UTO (renal calculi)

Question 8

What is chronic pyelonephritis

Answer 8

• Bacterial infection
• Vesicoureteral reflux / obstruction
• Caused by chronic UTO / repeated bouts of acute inflammation
• Intrarenal reflux (scarring / chronic inflammation)
• Border of cortex / medulla focal infiltrations of lymphocytes / plasma cells
• Renal tubes are dilated and filled with pink protein casts
• Connective tissue in interstitium, thickening of arteriole walls, lumen narrows (secondary hypertension)

Question 9

What is a UTI

Answer 9

• Short urethra of females allows faecal bacteria to easily enter urethra
• More common in sexually active women
• Urethritis, cystitis or pyelitis / pyelonephritis (complications)
• Dysuria, urinary urgency / frequency, fever, cloudy / blood tinged urine, back pain (kidneys)
• Treated with antibiotics

Question 10

What is acute tubular necrosis

Answer 10

• Destruction of tubular epithelial cells
• Caused by ischaemia, toxic injury, hypersensitivity to drugs, UTO (tumour)
• Loss of renal function, common cause of acute renal failure
• Tubule cell injury and disturbances in BF
• Loss of brush border, flattening cells, intratubular cast formation, sloughing
• Intratubular obstruction
• Pre-renal, initiation, extension, maintenance and repair

Question 11

What is renal cell carcinoma

Answer 11

• Primary carcinoma of the kidney parenchyma arising from the tubular epithelium
• Risk Factors: Smoking, obesity, hypertension, occupational exposure (asbestos, petroleum, heavy metals) and genetics

Question 12

What is transitional cell carcinoma

Answer 12

• Bladder can expand significantly (transitional epithelium)
• Most common cancer of bladder, ureter, urethra and rarely the renal pelvis
• Risk Factors: Smoking, industrial exposure, schistosoma haematobium infection, drugs and radiation

Question 13

What are cystic kidney diseases

Answer 13

- Heterogenous group of kidney diseases 
Cysts: 
- Single / multiple cystic spaces
- Variable size (1-5 cm)
- Clear fluid
- Confined to cortex
- Membrane singe layer of cuboidal or flattened cuboidal epithelium
- No clinical significance

Question 14

What is polycystic disease

Answer 14

• Hereditary disorder
• Multiple expanding cysts which ultimately destroy renal parenchyma
• Autosomal dominant or recessive

Question 15

What is autosomal dominant polycystic disease

Answer 15

• Partial replacement of renal parenchyma by cysts, bilateral, kidneys enlarged
• 15-30 years
• Defective PKD1 gene on chromosome 16
• Palpable renal masses and progression to choleric renal failure
• Hypertension, hematuria, UTI, ischemic atrophy of intervening renal substance
• Serous filled cysts with normal nephrons between cysts

Question 16

What is autosomal recessive polycystic disease

Answer 16

• Bilateral renal cysts without dysplasia
• Mutation in PKHD1
• Multiple cysts (smaller) evident at birth or early childhood
• Cystic dilation of renal collecting ducts
• Marked renal enlargement, leading to hypertension and progressive renal failure
• Biliary dysgenesis, abnormal bile duct formation with progressive periportal congenital hepatic fibrosis

Question 17

What is acute renal failure

Answer 17

• Failure of complete filtration of waste products from the blood
• Oliguria or anuria
• Recent onset of azotemia
• Sudden loss of kidney function
• Illness / injury / toxins that increase stress of kidney

Question 18

What is chronic renal failure

Answer 18

• Progressive loss in kidney function over months / years
• Prolonged uraemia
• Chronic renal parenchymal diseases (glomerular / tubulointerstitial lesions)

Question 19

What is end stage renal failure

Answer 19

• Kidneys permanently shut down, glomerular filtration rate < 15 mL / min
• Uraemia, ionic and hormonal imbalances, metabolic abnormalities, toxic molecule accumulation
• Fatigue, anorexia, nausea, cramps and pain
• Treated by hemodialysis or transplantation
• Stage 1 (damage, proteinuria, GFR < 90), 2 (damage, GFR 60-88), 3 (GFR 30-59), 4 (GFR 15-29) and 5 (failure, end stage, GFR >15)

Question 20

What are kidney stones

Answer 20

• Renal calculi, crystallised salts in renal pelvis
• Stones block ureter causing pressure / pain
• Causes: Chronic bacterial infection, urine retention, increase Ca in blood and increased pH of urine

Question 21

What are the types of kidney stones

Answer 21

• 70% Calcium stones
• 15% Struvite stones (UTI)
• 10% Uric acid stones (acidic urine)
• 1-2% Cysteine stones (genetic disorder)