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Oncocytoma
This is an essentially benign kidney growth that, depending on the reported series, constitutes between 3 and 7% or all kidney growths. While there is no way to discern an oncocytoma from forms of kidney cancer, an oncocytoma has classically been described as having a central scar which can occasionally be seen on radiographic imaging. The presence of the central scar does not exclude the possibility of kidney cancer. Similarly, oncocytomas have been associated with a “spoke wheel” pattern on angiograms. However, at present, renal angiograms are rarely indicated, and this finding is not specific enough to distinguish an oncocytoma from a kidney cancer variant.
While renal biopsies are sometimes considered prior to surgery when an oncocytoma is suspected, it remains very challenging to distinguish an oncocytoma from kidney cancer variants using just fine needle aspiration or core biopsies. Using these techniques, oncocytoma is difficult to distinguish from kidney cancer variants including conventional renal cell carcinoma and chromophobe renal cell carcinoma.
In 1998 Weirich and colleagues first noted a familial syndrome which they termed familial renal oncocytomaosis in which patients have multiple oncocytomas which usually occur in both kidneys. In this disease, patients also usually present at a young age. If familial renal oncocytomaosis is suspected, ablative techniques are considered an excellent option for treatment as the disease is multi-focal and multiple treatments over time are usually required.
The genetic characteristics associated with oncocytoma
are well characterized (link to benign kidney cancer variants) and
oncocytomas can usually be readily distinguished from kidney cancer
variants. Patients with Birt-Hogg-Dube syndrome often present
with oncocytomas and other types of kidney growths as well as characteristic
skin changes.
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