URORADIOLOGY

Imaging Findings

CT scan revealed a 4 cm mass lesion with distinct margins and smooth contour in the
 right kidney, with a central stellate low-density scar within the lesion, and peripheral
speckled calcification. The surrounding renal fascial fat planes were intact, with no right
 renal vein or IVC thrombus.

Diagnosis

Renal Oncocytoma / Renal cell carcinoma
Post-op histopathological evaluation: Oncocytoma

Discussion

The discovery of renal oncocytomas is frequently incidental. Its incidence is estimated at
about 4.3% of all renal tumours. The clinical course is almost invariably benign in the
majority of cases and long-term prognosis is favorable.

Typical features of oncocytoma on CT include homogeneous enhancement, smooth well
-defined borders and a central stellate scar. Extensive studies with CT however have failed
to reliably differentiate oncocytomas from renal cell carcinomas.

Invasive vascular techniques such as angiography can also be useful in the diagnostic
 workup but are not performed on a routine basis, especially with the advent of CT. Angiographically, there are no pathognomonic features for oncocytomas. They usually
display a smooth rim and parenchymal blush. It is classically described to have a vascular
supply arranged in a ‘spoke-wheel’ pattern with the vessels radiating towards the center
of the lesion. This by no means is specific since renal cell carcinomas may also have this
feature.

Management

The role of nephron-sparing surgery in the management of small, polar lesions in a young
patient is the emerging standard of care with the increasing discovery of incidental lesions
using non-invasive forms of imaging such as ultrasound and CT.

Net Links

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