Osteochondroma

What is osteochondroma?

Osteochondroma is a noncancerous growth of cartilage and bone. (“Osteo” means bone, “chondro” means cartilage and “oma” means tumor.) It's the most common kind of benign bone tumor. It usually appears near the ends of long bones, where new bone growth occurs in children and teens. This is the growth plate — a disk of developing cartilage tissue that eventually hardens into bone. Osteochondroma is an abnormal outgrowth of the growth plate. It develops in childhood and usually stops growing when their skeleton stops growing.

What are the different types of osteochondroma?

Osteochondroma occurs in two forms: as an individual growth, or as multiple growths. These are considered two different conditions.

• Solitary osteochondroma (osteocartilaginous exostosis) is most common. An individual solitary osteochondroma often causes no symptoms. Your healthcare provider may only discover an osteochondroma by accident when reviewing imaging for another condition. Since it isn't cancerous, it doesn't spread to other parts of the body. The cause is unknown. Researchers suspect it may be genetically inherited, but this isn't yet well-understood.
• Multiple osteochondromas occur in about 15% of cases. These multiple growths are usually the result of a genetically inherited condition. But they can also occur randomly (about 30% of the time). The inherited condition is called hereditary multiple osteochondromas or hereditary multiple exostoses (an exostosis is an external outgrowth of bone). Multiple osteochondromas are also noncancerous, but they pose a greater chance of complications, usually by interfering with the normal growth of your bones.

Is osteochondroma serious?

Generally, no. A solitary osteochondroma usually won’t require any treatment, unless the growth begins to put pressure on nearby tissues, nerves, blood vessels or other bones. In these cases, it may need to be removed. There is about a 1% chance of osteochondroma becoming cancerous over time. For this reason, your healthcare provider may want to keep it under observation.

More severe cases of multiple osteochondromatosis can cause abnormal bone growth in children. This might only affect their appearance, but sometimes can inhibit movement or cause discomfort. These cases will be monitored more closely for complications. Having multiple osteochondromas also slightly increases the risk that one will become cancerous — to about 5%.

What is the difference among osteochondroma, chondrosarcoma and osteosarcoma?

If osteochondroma were to become cancerous, it would then be considered chondrosarcoma. A sarcoma is a cancerous tumor that develops in connective tissue, including bone and cartilage. “Chondro” means cartilage. When cancer grows from an osteochondroma, it grows out of the cartilage cap. This is different from osteosarcoma, which is cancer in your bone.

Where does osteochondroma occur in your body?

Osteochondromas usually appear toward the ends of long bones, often at your joints, such as the knee, hip and shoulder. About 40% are at your knee. They can affect any bone with cartilage growth. Multiple osteochondromas can appear in many different places in the body at once.

What causes osteochondroma?

The majority of cases are a single osteochondroma, which has no known cause. It doesn’t result from injury. It is an irregularity in bone growth.

When there are multiple osteochondromas, it's usually an inherited condition caused by a gene mutation. But it can also occur randomly (about one-third of the time) for reasons unknown.

What does an osteochondroma look like?

Osteochondromas grow outward from the line of a bone and vary between 1 and 10 cm in size. They may have a visible stalk and a bulbous cap, like a mushroom or cauliflower. Osteochondromas with a visible stalk are called pedunculated. Flatter ones with a broader base are called sessile. Pedunculated osteochondromas are more common in solitary cases, and sessile osteochondromas are more common with hereditary multiple exostoses.

What does an osteochondroma feel like?

If you have an osteochondroma, you may not feel anything at all. But you might find a small, hard bump under the skin, close to a bone.

What are the symptoms of osteochondroma?

Most cases do not cause symptoms. They often go undiagnosed until they show up on an imaging test taken for an unrelated reason. However, you might notice:

• A small, hard lump on one of your bones.
• Pain with a particular movement if the tumor is rubbing against a tendon.
• Numbness or tingling in a particular spot if the tumor is putting pressure on one of your nerves.
• Circulation problems in a limb if the tumor is inhibiting a blood vessel.

In more severe cases, multiple osteochondromas can affect normal bone growth in children. Children with this condition might:

• Be unusually short.
• Have a crooked limb.
• Have an arm or leg that is longer than the other.
• Have a displaced hip joint (hip dysplasia).

How would you know if osteochondroma turned cancerous?

It's very rare for osteochondroma to become cancerous (malignant). But your healthcare provider will keep an eye on it just in case. They might want to do some testing if they’ve noticed:

• The tumor is causing unexplained pain.
• The tumor has continued to grow after the skeleton has stopped growing.
• The cap of the tumor is more than 1.5 cm thick in a fully grown patient.

How is osteochondroma diagnosed?

Your healthcare provider will begin with a medical history and physical examination. They’ll ask about your symptoms, and if they suspect osteochondroma, they’ll order an imaging test. Most osteochondromas will show up clearly on an X-ray. If more detail is needed, they might require an MRI or CT scan.

How is osteochondroma treated?

Most cases of solitary osteochondroma won't require any treatment. Your healthcare provider may want to take periodic X-rays to keep track of its growth, though. They'll also want to know if it's causing any pain or other symptoms. If so, they may recommend surgery to remove it.

Children with multiple osteochondromas will be monitored more regularly to keep track of old and new tumors and how the tumors affect the growth of their bones. Your healthcare provider may recommend removing tumors that interfere with bone growth. In some cases, they may recommend additional surgery to realign the bones.

Should an osteochondroma be removed?

Most do not need to be removed. However, your healthcare provider might recommend removal of a particular osteochondroma if:

• It causes pain or functional problems by putting pressure on nearby tissues, blood vessels or nerves.
• It inhibits normal bone growth.
• It appears malignant.

What should I expect from osteochondroma surgery?

The surgery is done under general anesthesia. The surgeon will make a small incision over the tumor and remove it at the level of the bone. This is usually a simple procedure. Certain cases where blood vessels or nerves are involved may be more complicated. Your healthcare provider will talk you through any risk factors resulting from the location of the tumor, and you should be able to go home the same day of surgery.

How long is recovery from osteochondroma surgery?

Many people can resume normal activities right away. In some cases, your healthcare provider might recommend a sling or crutch to limit movement or to keep weight off your limb for a few weeks. You and your healthcare provider will discuss different options for pain management for the first few days after surgery. The prognosis for full recovery is excellent.

Can an excised osteochondroma come back?

If an osteochondroma has been completely removed, it shouldn’t grow back. However, in very young children with multiple osteochondromas, there is a 5% chance of a new tumor growing in the same place. Osteochondromas don't continue to grow after the skeleton has stopped growing.

How should I take care of my osteochondroma?

Make sure your healthcare provider knows about it and checks on it from time to time. Let them know if you experience any symptoms.

Can osteochondroma go away?

Hereditary multiple osteochondromas is a genetic condition, which won't go away. However, some individual osteochondromas have been known to spontaneously regress and reabsorb into the bone. Scientists don’t know why this is. It’s rare for an osteochondroma to disappear on its own, but it’s not impossible.

A note from Cleveland Clinic

Osteochondroma is a noncancerous growth. It can be scary to hear that your child has a tumor of any kind, but not all tumors are cancer. Most of the time, osteochondroma appears as just one growth and won’t cause any problems. If your child is one of the few with multiple osteochondromas, you may be visiting your healthcare provider more often, just to keep an eye on them. Regular screening will ensure that the tumors don't interfere with the normal growth of your child’s bones. Osteochondromas that do cause problems are usually easy to remove through surgery.