Fig. 4

Pathologic examination of the resected specimen stained with hematoxylin and eosin. a Loupe image of the tumor revealed invasion throughout the entire CBD wall with serosal penetration. b Magnification of the part in the square in a. The tumor was structured with two components (black and white arrows). There was no transitional area between the two components. c Intermediate-magnification image of the part marked with a black arrow showed moderate differentiated adenocarcinoma. d The intermediate-magnification image of the part marked with a white arrow shows LCNEC, which made up approximately 90% of the tumor. The tumor was solid and cellular with necrosis inside. The tumor cells were joined together, and the cytoplasm was relatively large. e A high magnification of d shows that each nucleus variant was large and the heteromorphic nuclei division image was obvious