Radiologic findings in renal oncocytoma

The imaging findings of 36 renal oncocytomas in 32 patients were evaluated retrospectively. Twenty-two patients underwent ultrasound (US), 16 CT, 25 angiography, 19 urography, and 6 fine-needle biopsy. At US 8 of the oncocytomas were isoechoic, 7 hyperechoic, and 7 hypoechoic. The structure was homogeneous in 59% and nonhomogeneous in 41%. At plain CT 12 oncocytomas were homogeneously hypodense, 3 isodense, and one hyperdense. Contrast enhancement was homogeneous in 10 and inhomogeneous in 4 cases. A stellate scar was detected in one case, and in one case a contrast study was not performed. At angiography the oncocytomas were hypervascular in 21, hypovascular in 3 cases, and one was not detected. Nineteen of the tumors were well delineated. A spoke-wheel arterial pattern was detected in 3 tumors. The cytologic diagnosis was benign renal oncocytoma in 4 cases and highly suggestive of oncocytoma in 2 cases. We conclude that the homogeneity of a renal tumor at US and at CT may suggest the possibility of oncocytoma. US-guided fine-needle biopsy is a useful diagnostic tool in patients who need a precise presurgical diagnosis. (orig.)