The term, cholangiocarcinoma, is sometimes used to refer to any primary cancer of the biliary system; however, its use is often restricted to intrahepatic tumors and, therefore, it is not included in this summary. Adenocarcinomas are the most common type of extrahepatic bile duct cancers. The histologic types are listed below:[1]

• Carcinoma in situ.
• Adenocarcinoma, not otherwise specified (NOS).
• Adenocarcinoma, intestinal type.
• Mucinous adenocarcinoma.
• Clear cell adenocarcinoma.
• Signet-ring cell carcinoma.
• Adenosquamous carcinoma.
• Squamous cell carcinoma.
• Small cell (oat cell) carcinoma.
• Undifferentiated carcinoma.
  • Spindle and giant cell types.
  • Small cell types.
• Papillomatosis.
• Papillary carcinoma, noninvasive.
• Papillary carcinoma, invasive.
• Carcinoma, NOS.

Malignant mesenchymal tumors, although rare, include the following:

• Embryonal rhabdomyosarcoma.
• Leiomyosarcoma.
• Malignant fibrous histiocytoma.

References

1. Extrahepatic bile ducts. In: American Joint Committee on Cancer.: AJCC Cancer Staging Manual. 6th ed. New York, NY: Springer, 2002, pp 145-150.