Acquired cystic kidney disease: rapid progression from small to enlarged kidneys simulating adult polycystic kidney disease.

A 57-year-old man on chronic hemodialysis presented marked bilateral renal enlargement due to acquired cystic kidney disease (ACKD). He had been on hemodialysis for less than 3 years only (14 months prior to receiving a functional renal transplant which lasted 8 years, followed by 18 additional months of dialysis), before the diagnosis of ACKD was made following an episode of flank pain with gross hematuria. The marked changes in kidney appearance during this 11-year period were documented by serial ultrasound examination showing the kidneys to be of near-normal size before the start of dialysis (> or =10 cm in 1986), then shrunken and contracted 5 years later while having a functioning renal transplant (<5 cm in 1991), and markedly enlarged reaching the size of adult polycystic kidney disease after returning to dialysis (>13 cm in 1997). Since the risk of ACKD increases with duration of dialysis, we sought additional predisposing factors in this unusual case and found that 2 years after renal transplantation, the patient was diagnosed with breast cancer for which he was treated with surgical excision and tamoxifen. Based on ultrasound evidence that the tamoxifen treatment preceeded the appearance of the renal cystic changes, we wonder whether this drug may have played a role in the rapid development of ACKD.