Pediatric developmental, cystic and neoplastic kidney disease part II (Lovell)

Question 1

Renal agenesis

Answer 1

Failure of the metanephric diverticulum to develop. Left is more common. Bilateral is fatal postnatally.

Question 2

Renal hypoplasia

Answer 2

Smaller than usual. Contralateral side compensates.

Question 3

Renal dysplasia

Answer 3

Not a precancerous state, but indicates abnormal tissue differentiation. (eg cartilage developing in the kidney).

Question 4

Renal ectopia

Answer 4

Ectopic means something is out of place. Failure of kidney to ascent or to rotate medially. Can result in obstruction, can be discoid in shape.

Question 5

Horseshoe kidney

Answer 5

Incidence is 1/500. May be completely asymptomatic. Increased incidence of urolithiasis.

Question 6

ADPKD (Phenotype, inheritance, and associates)

Answer 6

PKD1 (90%) and PKD2 (10%). Incidence is 1/400 -1/1000 in caucasians. 25% of cases are spontaneous. Near 100% penetrance

PKD2 progresses more slowly (~10 years)

Presents in 40s, often with flank pain and hematuria. 50% progress to ESRD

Associations: Mitral valve prolapse (25%), Diverticulosis (80%), Hepatic cysts (80%), CEREBRAL ANEURYSMS (5-30%), pancreatic cysts (10%)

Question 7

ARPKD (Phenotype, inheritance, and associates)

Answer 7

PKHD1 mutation in fibrocystin (1/6000)

Presents as HTN in young children. Dilute urine, growth retardation (due to uremia?), progresses to renal failure requiring dialysis.

Tubules are malformed (hence the problems concentrating the urine). Will also have hepatic fibrosis.

Question 8

Multicystic dysplastic kidney (MCDK)

Answer 8

High incidence (1/1000 - 1/2000).

THE MOST COMMON CAUSE OF AN ABDOMINAL MASS IN THE NEWBORN PERIOD

Affected kidney is nonfunctional, generally asymptomatic. Still removed b/c people feel more comfortable w/o them in.

Question 9

Congenital Mesoblastic Nephroma (Clinical presentation, gross/histologic appearance, underlying genetics)

Answer 9

3% of pediatric tumors. But, most common tumor present at birth (3-6months of age). Solitary round infiltrating fibrous mass within the kidney. Complete removal of the kidney is a must-do.

Question 10

Wilms Tumor (Clinical presentation, gross/histologic appearance, underlying genetics)

Answer 10

aka nephroblastoma. Presents between 4-6 years of age. Solitary bulging pink-tan tumor. Tx with resection and chemotherapy.

Most common malignant kidney tumor of childhool (80%) 460 cases/year.

Classic histology is triphasic w/3 components:
Blastemal - small round blue
Epithelial - tubules
Stromal - fibroblastic

Possible to see muscle development within the tumor (dysplastic development of muscle fibers) –> called rhabdomyoblastic differentiation (10% of cases)

Question 11

What is an unfavorable histological feature (regarding prognosis) in Wilms tumor?

Answer 11

Anaplasia. Large, hyperchromatic cells and bizarre mitoses. Occurs in 4-5% of cases, and is due to a p53 mutation.

Requires an additional chemo drug (4 instead of the usual 3)

Question 12

Can Wilms tumor be bilateral?

Answer 12

Yes. 5-10% of cases. Automatically a stage V classification.

Question 13

What is Beckwith-Weidemann syndrome?

Answer 13

Phenotype includes gigantism, macroglossia (big tongue), and abdominal wall defects.
Due to imprinting defects.
5-7% also develop Wilms tumor.

Question 14

What is WAGR?

Answer 14

Wilms tumor
Aniridia
Genitourinary malformation
Retardation

Deletion of 11p13 –> includes PAX6 and WT1