Endothelial cyst of the adrenal gland associated with adrenocortical adenoma: preoperative images simulate carcinoma.

A 68-year-old woman was referred for characterization of a left adrenal incidentaloma. Endocrinological examinations indicated subclinical Cushing's syndrome, whereas the large volume (10 cm in diameter) and heterogeneous configuration of the tumor raised a strong suspicion of adrenal carcinoma. Hence, left adrenalectomy was performed. Histopathologically, this lesion was a thick hyaline-walled endothelial cyst, flanked with a compressed adrenocortical adenoma. The puzzling image resemblance of a variation of adrenal cyst to carcinoma necessitated histological examination for confirmative diagnosis. This is the first reported case of adrenal endothelial cyst associated with adrenocortical adenoma, the former of which alone is a rarity.