Review Question - QID 104569

A 50-year-old man is brought into the emergency room by emergency medical services after a motor vehicle collision. The patient is awake and responsive and states he was wearing a seat belt during the collision. The patient denies any head trauma and states he did not lose consciousness, but does state that his abdomen is painful. On exam, his vitals are HR 95, T 99.2, BP 135/60, RR 16. The patient's abdomen is tender to palpation in the epigastric area, but there is no rebounding or guarding. The patient has a CT scan an hour after the collision as shown on Figure A. He is found to have elevated amylase and lipase levels. After three days, he is discharged from the hospital. The patient returns 3 weeks later with epigastric pain and physical exam significant for a palpable mass that has been growing. He denies fever or other complaints. Figure B shows the CT scan of the patient upon his second visit. What is the best treatment for this patient?