Renal oncocytoma

Case contributed by Paul Simkin


Incidental finding on MRI workup for myositis.

Patient Data

Age: 45 years
Gender: Male


At the mid-pole of the left kidney, there is a 6.4 cm x 5.8 cm x 7 cm sharply circumscribed mass that demonstrates avid contrast uptake except within in a star-shaped central scar-like region. The left renal vein is normal. The right kidney is normal. There is no lymphadenopathy in the upper abdomen.

In the posterior right upper quadrant in subdiaphragmatic position, there is a 5.2 cm x 4 cm x 5.8 cm mass lesion associated with segment 7 of the liver medially. This demonstrates progressive peripheral nodular enhancement. The mass is closely associated with the right adrenal gland and difficult to separate from the medial limb. On coronal imaging, the enhancement pattern of adrenal tissue is however different from that of the margin of the lesion and a parasagittal multiplanar reformat the right adrenal gland appears separate and unremarkable. In segment 2 of the liver, there is a 2.8 cm lesion that displays the same type of peripheral nodular enhancement as the posterior left upper quadrant lesion. Both lesions are homogeneously T2 hyperintense ( but not CHF or cyst right ). Both lesions are consistent with cavernous hemangiomata.

There is no evidence of liver parenchymal disease. The hepatic vasculature is patent. The biliary tree is not dilated.

There is an 11 mm left adrenal nodule with an unenhanced attenuation of 28 Hounsfield units. The attenuation on the first phase is 167 Hounsfield units and on the delayed phase 67 Hounsfield units. Although not a dedicated adrenal washout CT, the relative contrast washout has been calculated at 56% which is in keeping with a lipid poor adrenal adenoma.



7 cm left renal mass - has imaging characteristics suggestive of an oncocytoma but a renal cell carcinoma is considered most likely, especially given the size of the lesion. Renal biopsy under US control could be performed if clinically indicated.

The posterior right upper quadrant lesion is more likely to be an exophytic cavernous liver hemangioma (than an adrenal hemangioma), with a further cavernous liver hemangioma seen in segment 2. The segment 7 lesion abuts the right adrenal gland that is otherwise unremarkable.

11 mm left adrenal lipid poor adenoma. No imaging followup is required however evaluation for endocrine hyperfunction should be considered.


The large renal lesion is clearly visible, including the central stellate scar. A percutaneous biopsy was performed.

Case Discussion

While the appearance of the left renal lesion, with the central stellate non-enhancing scar, is typical for renal oncocytoma, the possibility of renal cell carcinoma needs to be entertained due to the large size and increased incidence.

Biopsy, however, confirmed oncocytoma.

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