Review Question - QID 210784

A 48-year-old man presents to his primary care physician concerned about his weight. He states he has been gaining weight though does not feel he has changed his diet. The patient also states he has felt fatigued lately and not himself. He denies taking any medications or using any illicit substances at baseline. His temperature is 99.2°F (37.3°C), blood pressure is 177/108 mmHg, pulse is 100/min, respirations are 18/min, and oxygen saturation is 98% on room air. A physical exam is notable for an obese man with striae on his abdomen. A 24-hour urine free cortisol is collected and demonstrates an elevated cortisol level; however, a high dose of dexamethasone when administered results in no attenuation of cortisol release. A CT scan of the abdomen is within normal limits. Which of the following is associated with the most likely diagnosis?