[Cushing's syndrome due to bilateral oncocytic adrenal tumor]

Cushing’s syndrome accounts for approximately 20–30% of endogenous hypercortisolism cases, and adrenal involvement can be either unilateral or bilateral. Cushing’s syndrome due to bilateral adrenal tumors is extremely rare. Adrenal oncocytomas are another rare cause of endogenous hypercortisolism: about 13 cases are described in the literature. Oncocytomas are rare epithelial neoplasms, characterized by abnormally excessive accumulation of defective mitochondria in the cytoplasm of cells, and make up 1.8% of all adrenal neoplasms. We describe a 58-year old patient with Cushing’s syndrome and bilateral adrenal tumors. Multispiral computed tomography of the adrenals showed signs suspicious of lipid-poor atypical adenomas or malignant tumors. Surgical treatment was the method of choice, and the larger tumor was excised first. Due to the absence of remission of endogenous hypercortisolism the excision of the second tumor was performed. Morphological and immunohistochemical examination confirmed the diagnosis of bilateral oncocytic adrenocortical tumors with uncertain malignant potential. Cases of bilateral hormone-producing adrenal oncocytomas have not been described in the literature.