Types of Liver Cancer / Hepatobiliary Cancer

Liver Cancer / Hepatobiliary Cancer Types

Tumors of the liver are classified as primary (originating in the liver) or metastatic (spread from another body organ to the liver). Primary liver tumors may be further divided into those that are benign (noncancerous and remaining in the liver) or malignant (cancerous and likely to spread beyond the liver).

Metastatic tumors of the liver originate in the lung, colon, melanoma, gallbladder, breast, pancreas, or stomach. These metastases tend to gain access to the liver via the bloodstream, either through the portal vein or the hepatic artery.

Primary tumors can be further classified by the tissue of origin—either mesenchymal (undifferentiated tissue that helps form connective tissue) or epithelial (membranous tissue that lines a tube or cavity).

About 85% to 95% of all tumors are malignant and epithelial; 6% to 12% are benign and of epithelial origin; and approximately 1% to 3% of tumors are malignant and mesenchymal.

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Benign epithelial tumors include:

• Focal nodular hyperplasia – abnormal increase in the number of cells concentrated in a particular location on an organ
• Hepatocellular adenoma – often associated with the use of birth control pills or hormones

Benign mesenchymal tumors include:

• Hamartoma – tumor-like but non-neoplastic overgrowth with a disordered structure
• Cavernous hemangioma – tumor that involves blood vessels and soft tissue; may enlarge in women taking hormones; discontinuation of birth control pills hormone replacement therapy often recommended
• Lipoma – tumor of fatty tissue

Tumors of Heterotropic Tissues

Primary malignant epithelial tumors include:

• Hepatocellular carcinoma (HCC) – most common type of liver cancer; encompasses various forms of adenocarcinoma (cancer that originates in epithelial tissue)
• Hepatoblastoma – type of liver tumor that occurs chiefly in infants and children before age 3; thought to be caused by an abnormal gene
• Cholangiocarcinoma – tumor of the connective tissues of the bile ducts
• Hepatic cystadenocarcinoma – malignant neoplasm of glandular epithelium, characterized by fluid-filled cysts

Primary malignant mesenchymal tumors include:

• Angiosarcoma – begins in the lining of blood vessels
• Leiomyosarcoma – rare soft tissue cancer of smooth muscle tissue, usually in the uterus or wall of the stomach, abdomen, and pelvic region
• Lymphoma – arises in cells of the lymphatic system

Extrahepatetic tumors (tumors occuring outside the liver) include:

• Benign tumors of the gallbladder
• Malignant tumors of the gallbladder
• Adenocarcinoma – originates in epithelial tissue
• Squamous cell carcinoma – originates in squamous cells, the thin, flat cells resembling fish scales that are found in the tissue that forms the surface of the skin, the lining of the hollow organs of the body, and the passages of the respiratory and digestive tracts
• Small (oat cell) cell carcinoma – tumor cells appear small and round when viewed under a microscope
• Lymphoma – arises in cells of the lymphatic system
• Melanoma – skin cancer that arises in melanocytes, the cells that produce skin pigment
• Sarcoma – originates in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue
• Benign tumors of the extrahepatic bile ducts
• Adenoma – benign tumor of a glandular structure or of glandular origin
• Cystadenoma – rare benign liver lesion characterized by fluid-filled cysts
• Malignant tumors of the extrahepatic bile ducts

This list is not all inclusive, rather it shows the broad variety of primary liver tumors.

Hepatoblastoma

Hepatoblastoma is the most common primary malignant liver tumor in children, followed by hepatocellular carcinoma. It is usually diagnosed in children younger than 3 years old and occurs more often in males.

Signs of liver tumor in children tend to be abdominal swelling and discomfort. Complete resection can be accomplished in approximately 50% of children and is associated with cure rates of 30-70%. In those who are not initially resectable, liver transplantation may be an option.

Fibrolamellar Hepatocellular Carcinoma (FL-HCC)

This variant of HCC tends to be more indolent (develop slowly) than the classic variety. It has a slight female predominance and is not typically associated with hepatitis B or C, fibrosis, or elevated alpha feto-protein (AFP) levels. The response to chemotherapy is poor, so this variant is most often treated with surgical resection or transplant when possible.

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