Congenital abnormalities of bilateral kidneys.

A newborn infant was referred to the Department of Diagnostic Radiology, Princess Margaret Hospital, for further assessment for renal abnormalities detected by antenatal ultrasonography. Postnatal ultrasonography showed a cluster of noncommunicating cysts of varying sizes in the left renal fossa (Fig 1). The largest cyst was peripherally located. No normal renal parenchyma was detected in the left renal fossa. Hydronephrosis was seen in the right kidney (Fig 2), but the right renal parenchyma otherwise appeared normal. No hydroureter was seen.