Renal oncocytoma (pathology)

Case contributed by Dr Andrew Ryan


Incidental finding on CT scan.

Patient Data

Age: 50 years
Gender: Male

Coronal section of right kidney ('bivalved'). There is a round, tan tumor, 15mm in diameter, bulging into the hilar fat; it is quite hard to see because of similar color to the surrounding renal parenchyma. There is an incidental lower pole simple cortical cyst.


Histo (low power) - There are rounded to angular 'islands' of tumor cells surrounded by pale edematous stroma. This pattern is sometimes referred to as 'archipelangenous'  - from archipelago (see next picture).

Histo (high power) - well circumscribed nests of relatively uniform tumor cells with abundant eosinophilic (so-called 'oncocytic') cytoplasm. There is no significant atypia, mitotic activity or necrosis.


View of an island 'archipelago'. Photo courtesy of Radoslaw Botev from Wikimedia Commons.

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