[Radiological diagnosis of renal oncocytoma]

Eight patients (nine tumors) with histologically proven renal oncocytoma are presented. In all cases, differential diagnosis between renal oncocytoma and renal cell carcinoma could not be done on ultrasonography. On selective renal angiography, extended arteries surrounding the tumor margin was demonstrated in six of seven tumors without a spoke-wheel arterial supply. A sharp and smooth margin with capsule (lucent rim) could be found in five cases, and a spoke-wheel configuration of vessels could be seen in only two cases. A spoke-wheel pattern might be found with tumor growth. All tumors on computed tomography (CT scan) have a distinct margin, a smooth contour and a homogeneous appearance on contrast enhanced CT scan. The capsule and the presence of a central scar were clearly seen on T1 and T2 weighted images of magnetic resonance imaging (MRI). It is helpful to differentiate the oncocytoma from renal cell carcinoma. The modality of MRI may be useful in the preoperative diagnosis of oncocytoma.