Severe Cushing Syndrome Due to Ectopic ACTH Secretion by Pheochromocytoma

Abstract

Introduction: Ectopic ACTH production is a very unusual cause of Cushing Syndrome (CS). When it occurs, lung cancer is the main cause. Very rarely, this ectopic source of ACTH can arise from a Pheochromocytoma (Pheo). A recent literature review identified less than 100 cases described. We present a case of 28 years old woman who was referred for adrenalectomy for CS with notorious adrenal mass. However, during the investigation, ectopic ACTH due a Pheo was identified. Case Report: A 28-year-old woman required emergency care for ecchymosis and asymptomatic hypertension (BP: 230x130mmHg). Hyperpigmentation of the skin was evident on physical examination. Severe hypokalemia (K: 2.5mEq/liter) was detected. She denied taking any medication and was unaware of any previous illness. She always had normal BP measurements as well as laboratory tests. No family history of adrenal disease or secondary hypertension causes. During hospitalization, the hypothesis of CS was made and confirmed after: cortisol after 1mg dexamethasone: 44.5mcg/dl (<1.8mcg/dl) and 24h urinary free cortisol: 6228 mcg/dl (28-213mcg/dl). Concomitantly, a CT scan of the abdomen exhibited a left adrenal mass (3.1x2.8x3.5cm) of uncertain etiology and ACTH: 352pg/ml (<46pg/ml). Additionally, the patient presented hyperglycemia during hospitalization. After confirmation of the ACTH dependent CS, pituitary MRI was performed with normal results and a chest CT scan ruled out lung masses. As there was still no etiological confirmation and due to clinical deterioration, it was decided to start Ketoconazole 200mg/day, rising until 600mg and spironolactone with doses up to 250mg/day with a significant improvement in hypokalemia, decreased cortisol levels and optimal BP control. Due to the extremely high levels of ACTH and indeterminate adrenal mass, the hypothesis of ACTH ectopic due Pheo was postulated. Patient underwent abdomen MRI with left adrenal mass with hypersignal at T2 and urinary metanephrines levels: 6132mcg/24h (<289mcg/24h), urinary normetanephrines: 1808mcg/24h (<732mcg/24h). Once the diagnosis was elucidated, she received preoperative preparation with alpha blocker (Doxazosin) and underwent adrenalectomy without complications. After discharge, she received prednisone 10mg/day. The patient presented normalization of BP levels, as well as glycemic control with a slight improvement in skin hyperpigmentation. The pathology department confirmed Pheo and an ACTH expression was observed in immunohistochemistry. A genetic panel for Pheo is running with no results so far. Conclusion: Despite an extremely rare cause of CS, the ectopic production of ACTH by a Pheo has extremely high mortality rates, especially when not diagnosed or managed correctly. The clinicians must always remain alert and suspect this syndrome when the patient has a confirmed ACTH dependent CS associated with adrenal masses.