Q. A 45-year-old male presents to the emergency department complaining of headache, nausea, and vision changes over the past week. The patient reports that his headaches have been progressive in nature and increasingly severe, with the most recent headache being the worst he has ever experienced. The patient also reports that his vision has become blurred and that he has been experiencing double vision. He denies any fever, neck pain, or change in consciousness. His past medical history is significant for obesity, type 2 diabetes, and hypertension. The patient reports no known allergies and is not taking any regular medications. On physical examination, the patient appears uncomfortable but is oriented to person, place, and time. Cranial nerve examination is significant for bilateral papilledema and left sixth nerve palsy. The rest of his neurological examination is unremarkable. Given the patient's symptoms, you order a computed tomography scan of his head, which reveals a mass in the region of the hypothalamus and pituitary gland (see image). Based on the information you have at this point in time, which of the following is the most likely diagnosis?