Unilateral renal cystic disease: CT findings.

Unilateral renal cystic disease (URCD) is characterized by replacement of most of one kidney by multiple cysts scattered diffusely throughout the parenchyma without the formation of a distinct, encapsulated renal mass. There are no cysts in the opposite kidney or liver. The condition is nonfamilial and does not cause renal functional impairment. We describe the clinical and radiologic findings in two patients with URCD and discuss how the disorder usually can be distinguished from other renal cystic diseases using CT. Absence of a family history of renal cystic disease and the normality of the other kidney help distinguish URCD from autosomal dominant polycystic kidney disease. The diffuse nature of the cysts in URCD and the absence of a distinct encapsulated renal mass help distinguish URCD from cystic renal neoplasms.