Undifferentiated spindle and giant cell carcinoma of the common bile duct.

Undifferentiated spindle and giant cell carcinoma of the common bile duct has not been reported previously. We present here a case of 71-year-old man with the undifferentiated spindle and giant cell carcinoma of the common bile duct, including immunohistochemical findings. A nodular infiltrating tumor was located at the lower portion of the extrahepatic bile duct, and measured 1.2 x 0.6 cm in size. Histologically, the tumor was composed of proliferated sarcomatoid spindle tumor cells. Numerous multinucleated giant cells were intermingled with the sarcomatoid spindle tumor cells. Immunohistochemically, the tumor cells were positive for both cytokeratin and vimentin. We speculated that the tumor originated from epithelial cells, and showed sarcomatoid neplastic changes.