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Flashcards in Pediatric Kidney & Urinary Tract Deck (31):

What is renal agenesis or hypoplasia?

It is a failure of the metanephric diverticulum to develop. It is unilateral in most cases (left side is more common) and associated with single umbilical artery.

Bilateral agenesis is lethal


What is renal dysplasia?

It typically presents within the 1st decade of life. It is caused by abnormal metanephric tissue differentiation of the kidney tissue with cysts and heterotopic tissues such as cartilage due to pleuripotent potential of renal anlage.


What is renal ectopia?

Failure of the kidney to rise out of the pelvis or to rotate medially. It may result in ureteral obstruction and effected kidneys may be discoid in shape.


What is horseshoe kidney?

This is a relatively common occurance (1 in 500), where the two kidneys are fused usually at their lower poles. Since they are linked together, they are often ectopic and fail to rotate medially.

Horseshoe kidney causes increased incidence of urolithiasis.


What are the 3 general categories of cystic renal disease?

  • Acquired
    • simple
    • medullary sponge
    • acquired renal cystic disease (post dialysis)
  • Genetic
    • ADPKD
    • ARPKD
    • Nephronophthisis-medullary cystic kidney disease complex
    • Von Hippel Lindau
    • Tuberous Sclerosis
  • Developmental
    • Multicystic Dysplastic Kidney


What is ADPKD?

Autosomal dominant (adult) polycystic kidney disease


What mutations cause ADPKD?

Mutations in PKD1 (90%) on 16p13 and PKD2 (10%) on 4q21 which encode polycystin proteins 1&2 respectively.

PKD2 progresses about 10 years more slowly


What is the incidence of ADPKD? Do patients typically have family history? What is the penetrance?

Incidence is 1 in 400 to 1 in 1000 in caucasians.

25% of patients have no family history

near 100% penetrance with large cysts.


ADPKD typically presents in the 4th decade of life with what symptoms? How about in 5th? 6th?

4th decade- chronic flank pain, intermittent hematuria

5th - HTN and chronic renal failure

6th - about 50% progress to ESRD


ADPKD accounts for ____% of all cases of ESRD



In addition to kidney problems, what can ADPKD patients get?

Hepatic cysts (80%, patients older that 50 y/o)

Mitral valve prolapse (25%)

Diverticulosis (80%)

Cerebral aneurysms (5-30%)

Pancreatic cysts (10)%


What is ARPKD?

Autosomal recessive (infantile) polycystic kidney disease


What mutations cause ARPKD? Is it common?

PKHD1 on 6p21 which encodes fibrocystin.

Incidence is 1 in 6000 to 1 int 55,000 live births.

Heterozygous carrier frequency of 1 in 70.


When does ARPKD present and how does it present?

It presents in the first few years of life as HTN.

These babies have diminished urine concentrating ability and renal insufficiency. This progresses to renal failure requiring dialysis or transplantation.

Growth retardation is reported in 25%.


What's the difference between the cysts in ADPKD and ARPKD?

ADPKD has large cysts that can be seen throughout the kidney.

ARPKD has small cysts that are mainly in the collecting tubules.


ARPKD patients always have what hepatic finding?

Bile duct proliferation and periportal fibrosis called congenital hepatic fibrosis.


What is multicystic dysplastic kidney?

This is the most common cystic malformation of the kidney in infancy and the most common cause of abdominal mass in the newborn period. It is developmental and often associated with ureteral or ureteropelvic atresia. The affected kidney is nonfunctional, asymptomatic, and will involute over time.

1 in 1000-2000

Abnormal induction of the metanephric blastema by the ureteral bud. Might be due to a problem with formation of the mesonephric duct, malformation of the ureteral bud, or degeneration of the ureteral bud at an early stage.


What is the most common kidney tumor at birth (congenital)?

Congenital mesoblastic nephroma.

It only makes up 3% of pediatric renal tumors but it is the most common tumor at birth. It's usually detected around 3-6 months of age but can be detected on prenatal sonogram as a "ring sign"


What is the most important prognostic factor when treating congenital mesoblastic nephroma?

Complete resection


What's different about the cellular variant of congenital mesoblastic nephroma?

It is more invasive.

It exhibits a t(12;15)(p13;q25) ETV6-NTRK3 fusion transcript and sometimes trisomy 11.


What is the most common malignant kidney tumor of childhood?

Wilms tumor (nephroblastoma)

It accounts for 80% of pediatric renal tumors


When and how does wilms tumor typically present? And how is it treated?

Presents between 3-6 years of age as a solitary abdominal mass. Iti s treated by resection and chemotherapy (before or after)


What does the "claw sign" suggest?

Wilms Tumor


True or False: Always biopsy Wilms Tumor


Don't biopsy it. Biopsy of wilms tumor can cause spread because it's so soft.

They are so common around 3-6 y/o that it's assumed to be a wilms tumor


What is the classic histology of Wilms Tumors?

Triphasic appearance (3 distinct components, or any combination of them)

  • Blastemal (small round blue cells)
  • Epithelial (tubules)
  • Stromal (fibroblastic)

Sometimes rhabdomyoblastic component can be seen (skeletal muscle)

Or anaplasia (unfavorable prognosis)


What is this?

Wilms Tumor with rhabdomyoblastic differentiation


Whati s shown in this Wilms tumor?



Large, hyperchromatic cells and bizarre mitoses. Due to p53 mutation.

Diffuse anaplasia indicates chemoresistance and unfavorable prognosis.


What is Stage V Wilms Tumor?


frequently associated with genetic syndromes


What genes are associated with wilms tumor?

  • 11p13 WT-1
    • Intralobar rests
    • WAGR
    • Denys-Drash
    • Frasier
    • Isolated Diffuse
    • Mesangial Sclerosis
  • 11p15.5 WT-2
    • Perilobar Rests
    • Beckwith-Wiedemann
    • Rhabdomyosarcoma
    • Hepatoblastoma
    • Adrenocortical Carcinoma


What is beckwith-weidemann syndrome?

Gigantism, macroglossia (large tongue), and abdominal wall defects

Due to imprinting abnormalities on chromosome 11p15.5

5-7% develop wilms tumor as well as other embryonal tumors.


What is WAGR syndrome?

Wilms tumor

Aniridia (absence of iris)

Genitourinary malformation

mental Retardation

deletion of 11p13 includes PAX6 (responsible for aniridia and retardation) and WT1 (involved with the development of the genitourinary system)

30% of these patients develop wilms tumor