Fig. 2

a Macroscopically, the gallbladder mucosa was necrotic and black. The cystic duct and gallbladder bladder were thickened and white. b Microscopic examination revealed a poorly differentiated adenocarcinoma in the cystic duct. Scale bar is 50 μm. c Immunohistochemical examination revealed that the tumor cells were positive for ER. Scale bar is 50 μm. d The primary breast cancer was an invasive ductal carcinoma. Scale bar is 50 μm. e Immunohistochemical examination revealed that the tumor cells of the primary breast cancer were positive for ER. Scale bar is 50 μm. f Comparison between metastatic tumor cells (cystic duct) and primary breast cancer cells on immunohistochemical examination