An Extra-adrenal Abdominal Pheochromocytoma Causing Ectopic ACTH Syndrome

We report a 55-year-old woman with ectopic adrenocorticotropin (ACTH) secretion caused by extra-adrenal pheochromocytoma. The patient presented with a 6-month history of hypertension and diabetes mellitus. Her serum and urinary cortisol levels were extremely high and dexamethasone failed to suppress the cortisol secretion. Her plasma ACTH levels were also elevated (>300 pg/mL) and irresponsive to corticotropin-releasing hormone (CRH) or metyrapone administration. Gel filtration analysis of the patient's plasma detected the existence of large molecular weight ACTH being eluted with a major peak of authentic 1-39 ACTH. Abdominal computed tomographic scan and magnetic resonance imaging revealed a 5-cm paraganglioma located underneath the left kidney, in which (123)I-MIBG tracer specifically accumulated. Bilateral adrenal glands were diffusely enlarged. After surgical removal of the paraganglioma, the patient's clinical symptoms improved and biochemistry normalized including plasma ACTH, urinary free cortisol, and urinary catecholamines. Subsequent histologic evaluation of the transected paranglioma tissue revealed ACTH, synaptin, and chromogranin-A histologically immunostaining. Culture of primary cells collected from the resected paraganglioma demonstrated of in vitro production of ACTH, noradrenaline, and adrenaline. This is the first report of ectopic ACTH syndrome induced by an extra-adrenal abdominal paraganglioma.