An osteochondroma is a benign tumor made up of cartilage and bone. It is an abnormal mass that generally grows during childhood or adolescence near growth plates. Growth plates are found at the end of long bones in joints such as at the knees or shoulder. They are also known as osteocartilaginous exostasis.

Osteochondroma are extremely slow growing tumors that can grow undetected for years. Only when they grow past one centimeter in height, or when they begin to cause pain, do they become a concern. Osteochondroma generally grow outward and are only rarely seen growing inward. Their structure includes a “cap” of cartilage with a “stalk” that connects to the bone. Osteochondroma can cause problems when they grow into other parts of the body and hit nerves or cut off blood flow. Their cause is unknown and they affect men and women equally.

Signs & Symptoms

The most common sign of an osteochondroma is a painless bump. Some patients experience pain during movement. Numbness or tingling can occur when the osteochondroma is pressing on a nerve. A change in blood flow is possible if the osteochondroma is sitting on veins.

Diagnosing Osteochondroma

Doctors use x-rays, CT scans, and MRIs to view the osteochondroma. They perform a biopsy to rule out the risk of the tumor being cancerous. Osteochondroma are believed to make up approximately 35 – 40% of all benign bone tumors. There are two types of osteochondroma – single tumor and many tumors. Single tumor osteochondroma are called osteocartilaginous exostasis and osteochondroma with many tumors are called multiple osteochondromatosis.

Multiple osteochondromatosis have similar signs and symptoms to the single tumor type, but they are more serious. We also know that in approximately 70% of the cases multiple osteochondromatosis are inherited. They can lead to more complications and are more likely to develop into cancer. Children with severe multiple osteochondromatosis may be shorter in stature because of it and they can develop knock-knees or deformities in their arms.

Osteochondroma Treatment

If the osteochondroma is not causing any problems or pain your doctor will most likely simply advise you to keep an eye on it and have regular x-rays. If it grows to the point that it causes pain or problems the osteochondroma can be surgically removed in line with the rest of your bone.

Osteochondroma Prognosis

For single tumor osteochondroma the prognosis is very good. If they need to be treated at all surgery has a very high success rate. Multiple tumor osteochondroma can lead to other complications, but with proper monitoring and treatment patients have done very well.