A 40-year-old man with a history of alcohol consumption of 25-year duration is admitted with a history of a 6-lb weight loss and upper abdominal pain of 3-weeks duration. Examination reveals fullness in the epigastrium. His temperature is 99, and his WBC count is 10,000. Which is the most likely diagnosis?

The presence of an epigastric mass 2-3 weeks after the onset of acute pancreatitis strongly favors a pancreatic pseudocyst. The history of alcoholism points to pancreatitis as a possible etiologic factor in the differential diagnosis. Pseudocysts develop in 10% of patients following acute pancreatitis. Most of these, however, resolve spontaneously. They may also develop in patients with chronic pancreatitis or after pancreatic trauma.