Cystic Diseases

Question 1

Cystic diseases of the kidney

Answer 1

• can be congenital or acquired
  1. Cystic Renal Dysplasia
  2. Polycystic Kidney Disease
  3. Others: medullary cystic disease, acquired cystic disease, localised (simple) renal cysts

Question 2

Features of cystic renal dysplasia

Answer 2

• due to abnormal metanephric differentiation, with persistence of primitive/abnormal structures
• unilateral/bilateral
• may be associated with other abnormalities eg ureteric atresia/agenesis

Question 3

Morphology of cystic renal dysplasia

Answer 3

G:

• usually enlarged - however due to cyst, renal parenchyma is less due to disorganisation & scarring
• irregular in shape, multicystic

M:

• lobular disorganisation - loss of fn
• multiple cysts lined by flattened epithelium
• presence of primitive/immature structures - islands of undifferentiated mesenchymal cells, cartilage tissues, primitive ductal structures

Question 4

Features of polycystic kidney disease

Answer 4

1. autosomal recessive (childhood)
2. autosomal dominant (adult)
   - fairly common, causes 5-10% of cases of chronic renal failure
   - affects both kidneys

Question 5

Pathogenesis of polycystic kidney disease

Answer 5

• mutations in PKD1 & PKD2 genes - code for proteins polycystin-1 & 2
• develop multiple cysts (small - gradually enlarge) - renal fn initially normal
• eventually kidneys are composed almost entirely of cysts, very little parenchyma remaining - can cause abdo distension
• renal fn deteriorates over time - renal failure

Question 6

Complications of polycystic kidney disease

Answer 6

• rupture
• hemorrhage
• hematuria