A 50-year-old man was involved in a low-speed automobile collision and brought to the emergency department 4 weeks ago. Since the patient’s physical examination revealed mild abdominal tenderness, he underwent a CT scan of his abdomen that revealed an incidental 3.5-cm solid mass in the left adrenal gland. The patient was discharged from the emergency department with instructions to follow up for an outpatient evaluation of the left adrenal mass. During his visit, he indicates he is feeling well and is asymptomatic.

His heart rate is 70 beats/min and blood pressure 138/82 mmHg. His physical examination reveals no abnormal findings. What is the most likely diagnosis? (Answer is posted in the comment section below!) *This case is from the Docplexus Editorial Team for educative purposes only.