Chordoma

Chordoma is a rare malignant (cancerous) bone tumor that forms in your spine or the base of your skull. It’s a type of sarcoma.

Chordomas can occur at any point along your spine:

• About 35% develop in the base of your spine (sacrum).
• About 35% develop where your spine meets your skull (skull base). These are called clival chordomas because the bone in the skull base that’s most often involved is the clivus.
• About 30% develop in the vertebrae of your mobile spine — most commonly the second cervical vertebrae (in your neck) followed by your lumbar spine and then thoracic spine.

Chordomas typically grow slowly, but they can be difficult to treat due to how they invade nearby nervous system tissue.

They also tend to recur (come back) after treatment — usually in the same place. Chordomas spread to other parts of your body (metastasize) in 30% to 40% of cases.

If an advanced chordoma does metastasize, it most commonly spreads to your:

• Lungs.
• Nearby lymph nodes.
• Other bones.
• Liver.
• Skin.

What are the types of chordomas?

The World Health Organization (WHO) recognizes three distinct types of chordoma based on what the cells look like under a microscope (their histology):

• Classic/conventional chordoma: This is the most common type (80% to 90% of all cases). It’s made up of a unique type of cell that looks “bubbly.” Chondroid chordoma is a variant of this type. It makes up 5% to 15% of all chordoma cases. Chondroid chordoma often forms in the base of your skull.
• Dedifferentiated chordoma: This is a rare type of chordoma (less than 5% of cases) that appears as a mix of abnormal cells. It’s more aggressive, faster growing and more likely to metastasize than conventional chordoma.
• Poorly differentiated chordoma: This type is very rare. There have been fewer than 60 cases recorded in medical literature. Poorly differentiated chordoma is characterized by the deletion of a gene called SMARCB1, or INI1. These chordomas most commonly affect children and young adults.

Who do chordomas affect?

Chordomas can develop in anyone at any age, but they’re most likely to occur in adults aged 50 to 80. About 5% of cases affect children.

Men and people assigned male at birth are approximately 1.5 times as likely to have a chordoma as women and people assigned female at birth.

How common are chordomas?

Chordomas are rare. They affect about 1 person for every 1 million people per year. That means that about 300 people receive a chordoma diagnosis each year in the United States.

About 1% to 4% of all primary bone tumors are chordomas.