Renal oncocytoma developed in a long-term hemodialysis patient.

A case of renal oncocytoma which developed in a 38-year-old Japanese woman after 7 years of maintenance hemodialysis is reported. An encapsulated round tumor with a diameter of about 5 cm was incidentally discovered by abdominal echography. This is the first case of renal oncocytoma found in a long-term hemodialysis patient. Identification and differentiation of this subgroup from renal carcinomas are very important because of its benign nature. Careful clinicopathological investigation of renal tumors should therefore be required in hemodialysis patients.