Oncocytomas are benign neoplasms that may occur in many organs, including the kidney.
Males are twice as frequently affected as females.
Oncocytomas must be differentiated from granular renal cell carcinomas. The criteria for an oncocytoma include circumscription, lack of invasion into the renal parenchyma, capsule or perirenal fat, brown color and central scarring. Histologically, oncocytomas are characterized by an absence of mitotic figures or necrosis. Cytologic atypia may be present in an oncocytoma and is not a useful feature in the differential diagnosis. Extensive sampling of the tumor is required since small foci of necrosis may be present.