Q. A 45 year-old man comes to the emergency department because of severe abdominal pain that radiates to his back and two episodes of nausea and vomiting. His HR is 98 bpm, BP is 158/72 mmHg, RR is 20 bpm, and his temperature is 38°C. He smokes cigarettes "socially" (no more than 2 cigarettes per month) and drinks no more than 3 alcoholic drinks per week. His past medical history is significant for hypertension, for which he takes hydrochlorothiazide; migraine headaches, for which he takes duloxetine; and osteoarthritis, for which he periodically takes acetaminophen. On examination, he has severe epigastric pain and periumbilical ecchymosis. Serum studies are remarkable for the following: lipase is 625 units/liter (U/L) (normal is less than 160 U/L) and amylase is 550 U/L (normal is less than 140 U/L). Alkaline phosphatase level is 55 U/L (normal is between 44 - 147 U/L). Abdominal/Pelvic CT is ordered. Results are shown below. What is the most likely cause of this patient's condition?