Cyclic Cushing's syndrome due to ectopic ACTH secretion by an adrenal pheochromocytoma

Pheochromocytoma is a rare cause of ectopic Cushing's syndrome. We report on such a patient in whom ectopic ACTH secretion displayed a cyclic pattern. A 35-year-old woman was referred to us with a diagnosis of ACTH-dependent Cushing's syndrome. A 3.3 cm left-sided adrenal mass was noted at abdominal computerized tomography. At admission, clinical and hormonal data were unrewarding, so it was decided to continue to observe the patient. Four months later, she became symptomatic with hypertensive and psychotic crises and glycemic decompensation. By that time, a full-blown Cushing picture was evident. Severe hypercortisolism was documented with urinary free cortisol ranging 1500-2200 micrograms/24 h, serum cortisol 143-160 micrograms/dl and plasma ACTH 167-218 pg/ml. Neither ACTH nor cortisol values were significantly modified after high-dose dexamethasone, oCRH or metyrapone. Urinary catecholamine and vanilyl mandelic acid excretion were moderately elevated. Chest CT and total body MIBG scan were negative and magnetic resonance of the sella region was inconclusive. No center to periphery ACTH gradient was observed by inferior petrosal sinus catheterization, whereas a significant left to right gradient was found on selective adrenal vein catheterization. A left adrenalectomy was performed and a 4 cm medullary neoplasia was removed. The cells were immunostained for ACTH, neuron-specific enolase and A chromogranin. Signs and symptoms of Cushing's syndrome resolved with normalization of basal and dynamic endocrine evaluations.(ABSTRACT TRUNCATED AT 250 WORDS)