Renal oncocytoma in acquired renal cystic disease

Renal oncocytoma is a rare benign tumor of the kidney that accounts for about 5% of renal tumors. Acquired renal cystic disease (ARCD) is commonly seen in dialyzed patients. However, the occurrence of renal oncocytoma in ARCD has rarely been reported. We report such a case in a 67-year-old man who had hypertension-associated end-stage renal disease and had received regular hemodialysis for 5 years. Radiologic diagnostic studies demonstrated a renal mass in the left atrophic cystic kidney that increased in size from 2 cm to 4 cm during 2 years of follow-up. Under the diagnosis of renal cell carcinoma, he received left radical nephrectomy. The pathologic examination revealed renal oncocytoma with a well-cirumscribed, homogenous, mahogany-brown tumor on a background of ARCD. Although patients with ARCD have a higher incidence of renal malignancies, renal oncocytoma may occur in these patients and may be managed conservatively.