Multicystic Dysplastic Kidney

  • Etiology: Disconnect between ureteric bud and renal mesenchyma – the bud-branching signaling factors are never released and nephrons fail to develop leading to dysplastic tubular system and failure in ramification of ureteric bud
  • Imaging US Prenatal:
    — Commonly diagnosed at second trimester US
    — May undergo regression in utero or during early stages of life which leads to pseudo renal agenesis
    — Absence of renal pelvis
    — If bilateral have severe oligohydramnios or anhydramnios before birth
  • Imaging US:
    — Unilateral
    — Absence of normal renal parenchyma as renal parenchyma is replaced by multiple cortical and medullary cysts of various sizes that don’t communicate
    — Renal size decreases over time as kidney involutes along with compensatory hypertrophy of contralateral kidney over time
  • Imaging MAG3 scan: No or minimal renal function
  • DDX:
    — Renal agenesis: Multicystic dysplastic kidney has a normal shape to its adrenal gland while renal agenesis will have a pancake shape to its adrenal gland which will be a flat adrenal gland without visualization of the adrenal limbs
    — Pediatric cystic nephroma – Typically a unifocal multiloculated encapsulated cystic mass with multiple thin septa and no solid component
    — Ureteropelvic junction obstruction – Parenchyma can be identified around cysts, peripheral cysts (calyces) and a large central cyst (pelvis) which all communicate
    — Autosomal dominant polycystic kidney disease – Fetus or neonate may present with isolated hyperechogenic kidneys, number of cysts increase with age, multiple cortical and medullary cysts, if less than 15 years old and have a positive family history and greater than 1 cyst, if greater than 15 years old and have greater than 3 cysts either unilateral or bilateral
  • Complications:
  • Treatment: None as it involutes on its own
  • Clinical:
    — Second most common cause of abdominal mass in neonates and second most common cause of renal mass in neonates
    — Bilateral cases are incompatible with life
    — Involutes spontaneously
    — 15% associated with contralateral vesicoureteral reflux or ureteropelvic junction obstruction
    — 30% have abnormal contralateral kidneys
    — Low to no risk of HTN
    — Risk for cancer thought to be very low

Radiology Cases of Multicystic Dysplastic Kidney

US of multicystic dysplastic kidney
Sagittal US images of the right kidney show it to be larger than the left kidney and to have multiple cysts of varying sizes that do not communicate.
US of multicystic dysplastic kidney
Sagittal (above left) and transverse (above right) US of the right kidney shows an absence of renal parenchyma and multiple cysts of various sizes that do not communicate. Sagittal US of the left kidney (below) is normal.
US of multicystic dysplastic kidney
Sagittal US of the right kidney (above) shows it to contain multiple cysts, of varying size, that do not communicate and there is a paucity of renal parenchyma. Sagittal US of the left kidney (below) shows it to be normal.
US of multicystic dysplastic kidney
Sagittal US of the right kidney (above) shows it to contain multiple cysts of various sizes that do not communicate. There is also a paucity of renal parenchyma. Sagittal US of the right kidney 1 month later (below) again shows multiple cysts of various sizes that do not communicate and interval decrease in the amount of renal parenchyma present.

Radiology Cases of Multicystic Dysplastic Kidney in a Duplicated Kidney

US of duplicated kidney with multicystic dysplastic kidney in the lower pole
Sagittal US of the left kidney shows a normal appearing upper pole. The lower pole has two large cysts, of different sizes, that do not communicate.

Radiology Cases of Multicystic Dysplastic Kidney Resulting in Oligohydramnios

CXR of patient with oligohydramnios
CXR AP shows a bell-shaped chest with extremely low lung volumes.