Primary extra-renal clear cell renal cell carcinoma masquerading as an adrenal mass: A diagnostic challenge.

We present the first case of a nonmetastasizing renal cell carcinoma (RCC) masquerading as an adrenal mass, in the presence of normal bilateral native kidneys, in a young adult. The possibility of this mass developing in a supernumerary kidney was ruled out, since no identifiable renal tissue, pelvis or ureters was seen within the mass, nor was any separate systemic arterial supply to the mass seen. The diagnosis of extra-renal clear cell RCC was based on cyto-morphological features, further confirmed by immunohistochemistry findings. The origin of this extra-renal clear cell renal cell is proposed to be from the mesodermal embryonic rests.