Primary bilateral adrenocortical causes of Cushing's syndrome
Adrenal Cortex Diseases
Nontumorous primary adrenal causes of Cushing's syndrome are exceedingly rare. Herein we review our results with seven patients in whom there is biochemical evidence of a primary (adrenocorticotropin independent) bilateral adrenal cause of endogenous hypercortisolism. Each patient had low plasma adrenocorticotropin levels. All patients had elevated 24-hour urinary free cortisol levels and 17-hydroxycorticosteroids that were not suppressed by high-dose dexamethasone. Plasma levels of adrenocorticotropin and cortisol were not elevated by ovine corticotropin-releasing factor. No patient had a gradient between petrosal and peripheral adrenocorticotropin levels. No pituitary tumors were detected by magnetic resonance imaging or computed tomography. Five of six patients who underwent iodocholesterol scanning showed bilateral adrenal activity. Computed tomographic and magnetic resonance imaging of the abdomen demonstrated bilateral small adrenal glands in three patients, an adrenal mass in one patient with Carney's complex, and massively enlarged glands in three patients. Each patient underwent bilateral adrenalectomy and was given glucocorticoid and mineralocorticoid replacement. Pathologic examination of four of these bilateral adrenal specimens revealed primary pigmented micronodular adrenocortical disease, with adrenal gland weights between 2.5 and 13.4 gm (mean 5.2 gm). However, the remaining three patients had primary adrenocorticotropin-independent bilateral macronodular adrenocortical disease with adrenal gland weights between 32 and 81 gm (mean 52 gm). Although each of the patients with primary pigmented micronodular adrenocortical disease was cured by bilateral adrenalectomy through a posterior approach, two of the three patients required an anterior approach. We conclude that Cushing's syndrome can arise through two distinct forms of primary bilateral adrenal cortical disease. Computed tomography is important in evaluation of these patients because the size of the adrenal glands influences the surgical approach.