Computed tomographic and angiographic findings in renal oncocytoma

Nine cases with histologically proven renal oncocytoma are presented. In all cases, ultrasonography gave the first indication of a tumour and intravenous urography was tumour-specific in only six, whilst angiography was so in only four of the cases with peripheral extension beyond the normal organ limits. Examination by computed tomography showed retrospectively, in the three cases with smaller oncocytomas up to 3 cm in diameter, findings that seemed promisingly characteristic: without contrast medium, the tumour appeared homogeneously hyperdense in comparison with normal renal parenchyma, but homogeneously hypodense after injection of contrast medium. One of the smaller oncocytomas, however, showed regions of heterogeneity both with and without contrast medium. Only one oncocytoma of 4 cm diameter presented the central stellate, low-attenuation "scar" described by Quinn et al. The angiographic criteria cited by Ambos were fulfilled in only three of the larger oncocytomas. In four of the cases, the tumour was enucleated and the organ left in situ on the basis of frozen section diagnosis. Those patients with tumours extending outside the organ or those of questionable diagnosis on frozen section were treated by nephrectomy. In one patient, the pathologist suspected metastasis from the thyroid; hemithyroidectomy confirmed on oncocytic adenoma of the left thyroid lobe.