RESUMEN
INTRODUCTION: To report our experience of active surveillance of new bilateral masses after left laparoscopic partial nephrectomy for oncocytoma. METHOD: A 67-year old man underwent left laparoscopic partial nephrectomy for a renal mass and histology confirmed oncocytoma. At follow-up magnetic resonance imaging (MRI) showed new renal bilateral masses: hence, sonogram-guided percutaneous core renal biopsies were performed confirming the presence of oncocytoma in both kidneys. A re-biopsy was required because of an increasing of the left mass while a histological was also consistent with oncocytoma. RESULT: At follow of 8 years the patient is well and shows a normal renal function. CONCLUSION: Oncocytomas show minimal growth rate or progression. MRI has an important role in the appropriate follow-up of renal oncocytomas. Patients with biopsy proven oncocytoma may be managed conservatively by active surveillance (AS).