1. A 58-year-old man undergoes a pancreatoduodenectomy for a 4 cm mass in the head of the pancreas. Gross examination reveals a soft, tan, friable nodule within the main pancreatic duct. Microscopically, the tumor is composed of complex arborizing papillae with bridging and cribriform formations growing into the lumens of massively dilated ducts. The neoplastic cells have abundant granular eosinophilic cytoplasm and nuclei with single prominent, eccentric nucleoli. What is the most likely immunohistochemical profile of the tumor?