Possible pre-Cushing's syndrome due to an adrenal adenoma incidentally discovered.

We demonstrated the functional evaluation of adrenal incidentaloma in 8 patients who had no abnormal finding associated with Cushing's syndrome. Adrenal tumors were incidentally discovered by abdominal echogram in 5 patients and by computed tomography (CT) in 3 patients. Serum cortisol levels and urinary excretion of 17-hydroxycorticosteroids (17-OHCS) were within normal limits in four of 8 patients. Urinary excretion of free cortisol was also within normal limits except for patient 8. Urinary excretion of 17-OHCS, however, was not suppressed by dexamethasone administration in five of 8 patients. Excretion of urinary 17-OHCS did not increase in response to metyrapone in 3 of 4 dexamethasone-insuppressible patients, but increased in 3 dexamethasone-suppressible ones. Serum cortisol increased in response to exogenous ACTH in all 6 patients examined. 131I-Adosterol accumulation was found in only the tumor side in 7 patients and bilaterally in one patient. Adrenalectomy was done in 7 patients, and microscopic findings showed adrenocortical adenoma. Serum cortisol was significantly suppressed in response to dexamethasone in the post-operative stage in all 7 patients examined. These results indicate that these adrenal incidentalomas seem to have a cortisol over-production which is dexamethasone-insuppressible and ACTH-dependent, and that they can be classified as "Pre-Cushing's Syndrome."