Fig. 2

Macroscopic and pathological findings from the first resection. a The papillary and nodular tumor in the dilatation of intrahepatic bile duct (white arrow). b Complex papillary or tubular proliferation of atypical columnar or cuboidal cells with focal fine vascular stroma was observed in the dilated intrahepatic bile ducts. c Most of the tumor was composed of high-grade atypical cells that had enlarged nuclei, whereas low-grade dysplasia components were focally observed. d Tumor focally invaded into the stroma of portal area with mucinous trabecular or tubular fashion, although there was no invasion to the liver parenchyma. Immunohistochemistry findings are shown for e MUC1, f MUC2, g MUC5AC, and h MUC6