Etiology

 anatomical or functional obstruction of congenital lower urinary tract

• segmental obstruction
  • renal duplication

• unilateral obstruction
  • unilateral obstruction of pelviureteral junction
  • ureteral implantation anomaly
  • ureteral atresia

• bilateral obstruction +/- with Prune-Belly sequence
  • bilateral obstruction of pelviureteral junction
  • posterior urethral valves in boys
  • urethral atresia
  • megacystic-megaureter syndrome

Synopsis

 Renal dysplasia lesions

• cysts formation
• primary ductules
  • immature dysplastic tubulules surrounded by condensed mesenchyme
  • basement membrane may be thick and eosinophilic
• immature glomeruli
• immature tubules
• metaplastic cartilage foci (islands of immature cartilage)

 association with hydronephrosis and/or hydronephrosis
 dilated and tortuous ureters