Adrenal rest presenting as a renal cyst. A case report

The report presents a 42-year old female patient, in whom a cyst of the left kidney was diagnosed. The clinical presentation and gross picture suggested a simple cyst. The lesion was removed surgically; in the cyst wall, histology revealed structures identical to normal adrenal cortex. Based of this observation, the final diagnosis was established as the so-called adrenal rest. Such lesions are not uncommon in the kidney, but what was extraordinary in the described case was the macroscopic presentation. Thus, in differential diagnosis of cystic lesions of the kidney one should also take into consideration adrenal developmental abnormalities. This may be of particular importance in cystic clear cell renal carcinomas, the structure of which is well known to resemble the adrenal cortex.