One оf yоur cоlleаgues аsks for your аdvice on a patient: She reports symptoms of weight gain, anxiety, and stretch marks. Her blood work shows as follows: ACTH: 3.83 pg/ml (Range 12-21; Cortisol: 73 mg/dl (Range: 120-240). An MRI of the hypothalamus is normal and unremarkable. What is the likely pathology?