Fig. 4

Histological and immunohistochemical features of the neoplasm. a Prominent intraluminal papillary proliferation of the gallbladder (×20). b A papillary neoplasm is filling the lumen of the cystic duct (×20). c Pancreatobiliary-type epithelium with mild nuclear pseudostratification (×100). d MUC1 expression (×200). e MUC5AC expression (×200). f MUC2 negativity (×200)