Unilateral and segmental cystic disease of the kidney.

Unilateral and segmental cystic disease is a rare cystic disease of the kidney. Except for its unilaterality, it resembles autosomal dominant polycystic kidney disease on gross and histological examination. It also lacks genetic background and progressive deterioration of renal function. Only a small number of unilateral and segmental cystic disease of the kidney cases have been reported to date. The present case is a report of a 69-year-old man who had a large multicystic mass involving the lower and middle part of the right kidney with normal residual renal parenchyma at the upper pole. The left kidney was entirely normal. All the laboratory tests were within normal limits. Right nephrectomy was performed because of a strong suspicion of malignancy.