Renal oncocytoma: image diagnostics and therapeutic aspects.

The renal oncocytoma is a solid epithelial neoplasm with a generally benign course. The improved image diagnostics with the computerized tomography (CT) and magnetic resonance imaging (MRI) should today permit the identification of these lesions preoperatively so that conservative rather than radical surgery can be employed, especially in the presence of an early or incidental diagnosis, this latter being always more frequent today. Eighteen patients (9 women and 9 men) with renal oncocytoma are presented. The sizes of the lesions ranged from 1.5 to 12 cm and all were studied by means of ultrasonography, CT and MRI. The MRI was found to be superior to both the ultrasonography and the CT in identifying smaller than 5 cm lesions, presenting typical, homogeneous low-density images in the T1-weighted image sequences which appeared hyperintense in the T2-weighted ones. The presence of a central scar or stellate architecture, the absence of hemorrhage and necrosis and the presence of a pseudocapsule are other elements to differentiate an oncocytoma from a renal carcinoma. These aspects are less characteristic in greater than 5 cm lesions, making the differential diagnosis more difficult. Twelve patients were submitted to a radical nephrectomy and 6 underwent enucleation. The follow-up of the patients (6-74 months) showed a disease-free survival in 17, while one patient died of distant metastases. No local recurrences were observed after conservative surgery which should be considered the treatment of choice in cases of renal oncocytoma with lesions of less than 5 cm.