An incidental clear cell lesion of the kidney found at the time of cadaveric renal transplantation

We report a case of ectopic adrenal tissue (adrenal rest), found incidentally within a donor kidney being prepared for cadaveric renal transplantation. This is a known important mimic of clear cell renal cell carcinoma and, indeed, the clinical suspicion in this case was of a tumour of the kidney, the confirmation of which would have had implications as to the suitability of the kidney for transplantation. Pre-transplantation frozen section examination suggested the correct diagnosis, which was confirmed by subsequent review of paraffin-embedded sections and supportive findings on immunohistochemistry. We review the topic of developmental anomalies of the adrenal gland and outline an approach to differentiate ectopic adrenal tissue from clear cell renal cell carcinoma.