Internal Medicine Resident University of Arizona College of Medicine – Phoenix, AZ, Banner Health Scottsdale, Arizona, United States
Introduction : Cushing’s syndrome is a rare, life-threatening endocrine disorder due to excess cortisol from either an adrenocorticotropic hormone (ACTH)-independent or ACTH-dependent source. Endogenous Cushing’s syndrome due to ACTH-secreting pheochromocytomas remains a diagnostic and therapeutic challenge due to the additive effects of both cortisol and catecholamine excess. Given its rarity, there are limited studies on its diagnosis, management, and outcomes. Here, we present a complicated case of severe Cushing’s syndrome due to an ectopic ACTH-secreting pheochromocytoma with severe thrombocytopenia.
Case(s) Description : A 54-year-old male with hypertension and type 2 diabetes presented with altered mental status. Vitals were hemodynamically stable. Initial workup revealed low hemoglobin (7.1 g/dL), thrombocytopenia (12 K/MM3), hypokalemia (3.1 mmol/L), hyperglycemia (228 mg/dL), elevated ACTH (1091 pg/mL), hypercortisolism (207 µg/dL) and elevated serum metanephrine (145 pg/mL).DOTATE scan showed a 12 cm neuroendocrine tumor in the right adrenal gland. Following multidisciplinary tumor board discussion, the patient began treatment with low-dose etomidate drip to lower cortisol levels. The patient underwent platelet transfusion prior to laparoscopic right adrenalectomy which proceeded without complications. Surgical pathology confirmed the diagnosis of ACTH-secreting pheochromocytoma. The patient’s severe thrombocytopenia resolved postoperatively. He received 6 months of hydrocortisone taper to prevent adrenal insufficiency. He returned gradually back to normal life and work following surgery.
Discussion : Cushing's syndrome results from prolonged exposure to excess cortisol. Cortisol synthesis involves the regulated feedback loops of the hypothalamic–pituitary–adrenal axis; the corticotropin-releasing hormone (CRH) induces the release of ACTH that ultimately elevates cortisol. We illustrate a complicated case of Cushing’s syndrome due to an ACTH-producing pheochromocytoma. Pheochromocytoma is an adrenal medullary tumor that arises from chromaffin cells and secretes catecholamines. ACTH-producing pheochromocytomas are extremely rare with fewer than 100 cases reported in the literature. Our case highlights the importance of including ACTH-producing pheochromocytomas on the differential when evaluating Cushing’s syndrome, especially when cortisol, ACTH and metanephrine levels are all elevated. Low-dose etomidate drip is very effective to lower cortisol level which can be used in severe hypercortisolism safely. A multidisciplinary approach is crucial to diagnose and successfully treat patients with severe endogenous Cushing's syndrome.
