Cushing syndrome and Cushing disease Quiz: Ace Your Exams

A 73-year-old woman presents to the primary care clinic for evaluation of six months of easy bruising, thinning skin, polyuria, hypertension, and central obesity with violaceous striae. The patient has no significant past medical history and takes no medications. She has been smoking one pack of cigarettes daily for the past 45 years. Temperature is 37.0ºC (98.6ºF), blood pressure is 152/91 mmHg and pulse is 90/min. Supraclavicular and dorsocervical fat pads are noted to be enlarged. Neurologic examination shows proximal muscle weakness bilaterally. The abdomen is obese with dark terminal hairs and violaceous striae. 24-hour urinary free cortisol and late-night salivary cortisol levels are significantly elevated. Computed tomography (CT) imaging of the abdomen shows a 9-mm left adrenal mass. Magnetic resonance imaging (MRI) of the brain shows a 7-mm pituitary mass. The patient undergoes inferior petrosal sinus sampling which does not demonstrate a central-to-peripheral adrenocorticotropic hormone (ACTH) pituitary gradient. Which of the following is the best next step in management?