Q. A 35-year-old man presents to the emergency room with a three-day history of severe headache, palpitations, diaphoresis, and tremors. He reports that these episodes occur several times a day and last for about 30 minutes. He has a history of uncontrolled hypertension, which was diagnosed five years ago. He also reports a family history of hypertension and sudden cardiac death in his father at the age of 50. The patient's vital signs on presentation are: blood pressure 200/110 mm Hg, pulse rate 130 beats/minute, and respiratory rate 22 breaths/minute. The physical examination reveals a hypertensive patient with moderate sweating and tremors. Further evaluation reveals elevated levels of catecholamines in the patient's blood and urine samples. Further evaluation reveals elevated levels of homovanillic acid and vanillylmandelic acid in the patient's blood and urine samples. What is the most likely diagnosis?