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Oncocytoma

September 2, 2012

Oncocytoma

  • Benign tumor

 

  • Represents 10-15% of small solid renal neoplasms (<3 cm)

 

  • Arise from proximal tubular epithelium (oncocyte)

 

  • Range in size from 1.5 – 13 cm (mean 6.3 cm)

 

  • CT Features:

 

  • Well-defined masses with smooth, rounded margins
  • Slightly hypodense to the rest of renal parenchyma on NECT
  • Homogenous enhancement after IV contrast admn
  • Capsule may be present around the tumor
  • A central, sharply defined stellate scar present in 25-33% cases of large oncocytomas & strongly suggests the diagnosis
  • Currently there is no specific CT finding to differentiate oncocytoma from RCC

 

 

  • Angiography – The classic angiographic findings for oncocytoma are:
    • spoke-wheel pattern
    • homogenous nephrogram
    • sharp, smooth rim

 

  • MRI Features:
    • T1- Iso to hypointense to normal parenchyma
    • T2- Variable appearance
    • Post Gd enhancement, but less than renal parenchyma

 

  • FNAC has been successful to differentiate oncocytoma from RCC. However differentiation of oncocytoma & chromophobe RCC is esp. difficult.

 

  • Small tumors may be treated with partial nephrectomy because of excellent prognosis. Nephron-sparing surgery should be considered. There is an increased association of clear cell carcinoma in these pts in either kidney.
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Categories: Radiology
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