Osteochondroma is a common, non-cancerous bone tumor that develops in the growing bones of children. It’s usually solitary and painless. A hereditary condition causes multiple osteochondromas in some children. They can affect the normal growth of the bones and sometimes need to be removed through surgery.
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.
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Osteochondroma occurs in two forms: as an individual growth, or as multiple growths. These are considered two different conditions.
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%.
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.
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.
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.
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.
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.
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:
In more severe cases, multiple osteochondromas can affect normal bone growth in children. Children with this condition might:
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:
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.
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.
Most do not need to be removed. However, your healthcare provider might recommend removal of a particular osteochondroma if:
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.
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.
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.
Make sure your healthcare provider knows about it and checks on it from time to time. Let them know if you experience any symptoms.
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.
Last reviewed by a Cleveland Clinic medical professional on 10/20/2021.
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