A 54-year-old woman presents to the emergency department with a 3-month history of worsening abdominal discomfort, anorexia, and 20-lb weight loss. She has no past medical conditions and was fully active prior to the onset of her symptoms. On physical examination, a nontender but palpable distended gallbladder at the right costal margin is noted. Laboratory findings are notable for a hemoglobin level of 14 g/dL, white blood cell count (WBC) of 4500/µL, platelet count of 450 × 10³/µL, alanine aminotransferase level of 64 U/L, aspartate aminotransferase level of 88 U/L, and total bilirubin level of 1.1 mg/dL. Multiphasic helical computed tomography (CT) scan of the abdomen detects a 2-cm pancreatic head mass with mild biliary duct dilatation.