Adenosquamous carcinoma of the common bile duct: a case report.

Reported here is a case of primary adenosquamous carcinoma of the common bile duct. This unusual variant of the ordinary adenocarcinoma has not, to the best of our knowledge, been previously reported as occurring in the extrahepatic bile ducts. A tumor of notorious prognostic significance, it represents an exceedingly rare and peculiar biological phenomenon of malignant metaplastic change.