A Case of Bilateral Macronodular Adrenal Hyperplasia with Cushing's Syndrome Treated by Unilateral Adrenalectomy

In order to differentiate the causes of Cushing's syndrome; whether it is pituitary or adrenal-dependent, a high dose dexamethasone suppression test is usually performed but this does not always correlated with the imaging diagnosis. We report a case of bilateral macronodular adrenal hyperplasia, which was thought to be independent to adrenocorticotrophin (ACTH) stimulation. At first we thought it was pituitary-dependent Cushing's syndrome, due to its suppression by high dose dexamethasone. However, we found no abnormal findings on the brain sella magnetic resonance image (MRI). A significant finding, however, we found bilateral adrenal masses on the abdominal computed tomography (CT). We performed percutaneous selective adrenal venous sampling (pSAVS), and confirmed hypercortisolism of the left adrenal mass only. Therefore, we decided to remove the left adrenal gland to preserve the residual function of the right adrenal gland. After the left adrenalectomy, the patient became normotensive, and their buffalo hump disappeared, and her 24 hour urinary free cortisol level returned to normal.