Description

• Multicystic dysplastic kidney (MCDK) disease is the most severe type of cystic renal dysplasia and is characterized by multiple, noncommunicating cysts which are divided by dysplastic tissue.
• In general, there is no functioning renal tissue in a MCDK.
• Involutes over time (usually within the first 5 years)

Epidemiology

• Incidence is 0.3 to 1 in 1,000 live births
  • Most cases are detected antenatally.
• Affects boys > girls
• Left kidney > right kidney
  • Usually unilateral but can be bilateral

Pathophysiology

• Initial growth of the ureteric bud is normal; then renal development halts at a later stage.
• Histology shows disordered renal tissue with areas of undifferentiated mesenchymal cells, abnormal differentiation (i.e., cartilage), rare nephrons.
• Etiology unknown; recent studies suggest genetic cause.

Commonly Associated Conditions

Associated anomalies of contralateral GU tract include the following:

• Vesicoureteral reflux (VUR), most common, occurs in ~25%.
• Renal hypoplasia
• Ureterocele
• Ureteropelvic junction (UPJ) obstruction
• Genital anomalies