Unilateral renal cystic disease.

Unilateral renal cystic disease (URCD) is a distinct entity that is one of the renal cystic diseases. URCD consists of a cluster of multiple cysts in part or most of one kidney with no association of cystic disease in the contralateral kidney. URCD is a nonfamilial, nonprogressive disorder and is not related with autosomal dominant polycystic kidney disease (ADPKD). We report a case of URCD with six-year CT follow-up. Confinement of the cystic disease to one kidney with an absence of cysts in other organs such as liver or pancreas distinguish URCD from ADPKD. Absence of an encapsulated mass and intervening normal renal parenchyma between the cysts can differentiate URCD from cystic renal tumors.