Associated with atresia of the entire pelvic and infundibular system. Has a grapelike appearance with multiple noncommunicating smooth walled cysts of variable size. Thirty-three percent have contralateral renal anomalies such as MCDK, congenital ureteropelvic junction obstruction, renal hypoplasia, or malrotation. An atypical hydronephrotic type may have isolated ureteral atresia with multiple cysts communicating with a dilated renal pelvis with dysplastic renal tissue forming trabeculae between the cysts.
Abdominal films show a noncalcified abdominal mass.
Ultrasound shows multiple non communicating cysts of variable size. No renal pelvis is identified. The atypical hydronephrotic type can be confused with congenital hydronephrosis and nuclear medicine can be used to differentiate between the two of these because congenital hydronephrosis will have a rim of functioning tissue on the nuclear medicine scan while MCDK has no functioning tissue. Note that an IVP can't be done in the first 10 days of life because the newborn's glomerular filtration rate, plasma concentration, and renal tubular concentration are all decreased. See References Chapter.