Clinical Presentation

A newborn with a cystic mass seen on prenatal ultrasound.

Further Work-up

(A) Longitudinal sonogram: There are multiple cystic structures in the kidney that do not communicate (arrow). Normal renal cortex is not visualized. (B) MAG3 (mercapto-acetyl-triglycine) nuclear medicine scan: There is no uptake or excretion in the left kidney (arrow).

Differential Diagnosis

• Multicystic dysplastic kidney (MCDK): The finding of multiple discrete, noncommunicating cysts in a kidney demonstrating no function is consistent with MCDK.