Abstract. Ectopic ACTH syndrome is rarely caused by pheochromocytoma. We report a case of a 28-year-old woman with Cushing's syndrome due to ACTH-producing adrenal pheochromocytoma. She had delivered preterm baby at 32nd week of gestation with 'severe preeclampsia'. After delivery, persistent hypertension accompanied by severe headache led her to being misdiagnosed as Cushing's syndrome due to right adrenal adenoma (normal plasma ACTH level) and cerebral vasculitis of unknown etiology. She was referred to our hospital for surgical treatment. Repeated biochemical studies suggested coexistence of ectopic ACTH syndrome and pheochromocytoma. To reverse her clinical deterioration, right total and left subtotal adrenalectomy was performed with presumptive diagnosis of 1) right adrenal pheochromocytoma causing ectopic ACTH syndrome or 2) coexistence of ACTH-dependent Cushing's syndrome and right adrenal pheochromocytoma. Pathologic examination of right adrenal mass revealed pheochromocytoma which showed strong immunostaining for ACTH. Plasma ACTH and urinary cortisol excretion normalized after surgery, but she succumbed to multiple cerebral infarcts and disseminated intravascular coagulation. Pregnancy and inappropriately low plasma ACTH at initial evaluation might have hampered early diagnosis. To our knowledge, this is the first description of a case with ectopic ACTH syndrome due to pheochromocytoma associated with pregnancy.

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