A 32-year-old man with an unremarkable medical history presented to the ambulatory clinic with complaints of nonlocalized abdominal pain. The results of a physical examination were unremarkable. The results obtained from liver, pancreatic, and renal testing were within the reference intervals, and the results of both a fecal occult blood test and an investigation for parasites in the stool were negative. Laboratory investigations also revealed a plasma carbohydrate antigen 19-9 (CA19-9) concentration of 3103 IU/mL (reference interval, 2-40 IU/mL). After this finding, abdominal ultrasonography and nuclear magnetic resonance imaging evaluations were made.