Cystic renal cell carcinoma, suspected because of lack of regression of renal cysts after renal transplantation in a dialysis patient with acquired renal cystic disease.

A 34-year-old man who had been on dialysis for about 6 years, and had acquired renal cystic disease, received a renal transplantation. However, in spite of the success of the transplantation, one area without cyst regression was observed in the original kidney. Therefore, carcinoma was suspected and nephrectomy was performed. Histology revealed cystic renal cell carcinoma (RCC). No case of cystic RCC occurring in a dialysis patient has previously been reported. Cystic RCC should be suspected in a cystic mass in the original kidney which does not regress after successful renal transplantation.