Endoscopic retrograde cholangiopancreatography (ERCP) and percutaneous transhepatic cholangiography (PTHC) may show a heterogeneous aspect in the bile duct that may be related to the tumor or to intraluminal mucin [12] (Fig. 7); sometimes, direct communication between the tumor and the bile ducts can be seen, the endoscopic visualization of the flow of mucin through the ampulla of Vater is rare [13]. Here, MUC5AC is linked to neoplasm.