Congenital malformations of kidney

Question 1

Where is an ectopic kidney usually located? What are the potential consequences? Which species might develop this in utero and why?

Answer 1

Caudally in the pelvic cavity, or close to the inguinal canal of the caudoventral abdominal wall
Would be fine but ureter is also usually ectopic or kinked
Seen in pigs due to hypovitaminosis A (as well as cats and dogs)

Question 2

List five microscopic features of dysplastic kidneys

Answer 2

1. Persistent S phase glomeruli
2. Foci of undifferentiated mesenchymal tissue
3. Blind-ending, dilated collecting tubules
4. Atypical tubular epithelium
5. Primitive metanephric ducts

Question 3

List three mechanisms for renal cyst development.

Answer 3

1. Obstruction of nephron
2. Abnormality in tubular basement membrane
3. Disorderly hyperplasia of tubular epithelial cells leading to tubular obstruction

Question 4

Briefly outline the pathogenesis of polycystic kidney disease

Answer 4

Mutation in gene encoding polycystin protein alters cell:cell and cell:matrix interactions of renal tubular epithelial cells (sometimes also bile duct and pancreatic duct epithelial) leading to dysregulated growth and cyst formation.
May be autosomal dominant or recessive.

Question 5

What might lead to development of renal retention cysts?

Answer 5

Obstruction of nephron by scar tissue
Chronic hypokalemia
Drugs that promote renal tubular hypoplasia including corticosteroids

Question 6

List three things that may cause acquired perinephric psudocyst development. What normally makes up the fluid of the pseudocyst?

Answer 6

Trama, neoplasia, passive congestion of the kidney

Usually contains lymph +/- urine +/- blood +/- transudate