Rare Liver Disease Month Focus: Rare Forms of Liver Cancer

Liver cancer is cancer that occurs in the liver. Primary liver cancer is cancer that begins in the cells of the liver. Secondary liver cancer develops when cancer cells from another part of the body spread to the liver; this type of cancer may also be referred to as metastatic liver cancer. There are a few types of primary liver cancer. The type of liver cancer someone has is determined by which type of liver cell has become cancerous.

Hepatocellular carcinoma (HCC) is the most common type of liver cancer. The information in our liver cancer section is mostly about HCC because it accounts for about 75% of all liver cancers. HCC starts in hepatocytes, the main type of liver cell. Most of the liver is made up of hepatocytes, about 80%, and they perform the majority of the liver essential functions. HCC is most likely to occur in people who have severe liver damage, or cirrhosis. Since 1985, rates of new cases of HCC began steadily increasing in the United States. In the last 10 years, new cases of HCC have remained relatively steady.

In honor of #RareDiseaseDay on February 28, we wanted to highlight other, rare forms of liver cancer.

Cholangiocarcinoma

Cholangiocarcinoma are more commonly known as bile duct cancers. This group of rare cancers begin in the bile ducts. There is a vast network of very small tubes, called bile ducts, responsible for transporting bile made in the liver to the gallbladder or small intestine. Bile ducts inside the liver come together to form the right and left major bile ducts which lead out of the liver to meet the common bile duct.

There are three main types of cholangiocarcinoma, depending on where in the biliary system cancer forms:

•  Intrahepatic cholangiocarcinoma occurs in the small bile ducts within the liver. This is the least common form of bile duct cancer.
•  Klatskin tumor or hilar cholangiocarcinoma occurs where the right and left bile ducts meeting the common bile ducts. This is the most common form of bile duct cancer.
•  Extrahepatic cholangiocarcinoma occurs in the section of bile ducts outside the liver.

There have been some risk factors identified for the development of cholangiocarcinoma but some people who are diagnosed have no obvious risks. Some of the more well-established risk factors include primary sclerosing cholangitis, exposure to certain toxins and infections, and individuals with chronic, ongoing inflammation of the bile ducts.

Fibrolamellar Carcinoma

Fibrolamellar carcinoma is a very rare cancer of the liver that usually occurs in teens and adults under the age of 40. Unlike other types of liver cancers, this type happens in people who have healthy livers. Fibrolamellar carcinoma was once thought to be a different form of hepatocellular carcinoma but many physicians now consider it a separate type of cancer, distinct from HCC.

Fibrolamellar carcinoma is an ultra-rare form of cancer affecting both men and women; this type of cancer accounts for about 1% of people with primary liver cancer in the United States.

Hepatoblastoma

Hepatoblastoma is an extremely rare type of liver cancer that primarily affects children from infancy until around age 5. Most kids are diagnosed during the first 18 months of life. Although this is a rare type of cancer, it is the most common form of liver cancer in young children.

The cause of this type of cancer is unknown. Children have a high risk for developing hepatoblastoma if they were born prematurely, had a very low birth weight, or have certain genetic conditions (including but not limited to hemihypertrophy syndromes, Beckwith Weidemann, Trisomy 18, and germline APC gene mutations).

Liver Angiosarcoma

Angiosarcoma is a rare type of cancer that forms in the cells of the blood or lymph vessels. Lymph vessels are part of your immune system, responsible for collecting and removing bacteria, viruses, and waste products from the body. The liver is the 5th most common site for an angiosarcoma to form. However, liver angiosarcoma is the 3rd most common type of primary liver cancer. Liver angiosarcoma usually occurs in older men, in their 60s or 70s. This form of liver cancer is very aggressive and usually is not diagnosed until an advanced stage.