Clinical Presentation

A 6-month-old boy with a palpable abdominal mass.

Further Work-up

(A) Longitudinal ultrasound image: There is a multicystic mass in the left kidney (arrow). The cysts do not appear to communicate. (B) Contrast-enhanced computed tomography (CT) image: There is a multiloculate, fluid-density mass herniating into the left renal collecting system. Normally enhancing kidney surrounds it (arrows).

Differential Diagnosis