Also called osteocartilaginous exostoses, osteochondroma is an overgrowth of cartilage and bone near the end of the bone near the growth plate. This type of overgrowth can occur in any bone where cartilage eventually forms bone. Most commonly,
it affects the long bones in the leg, the pelvis, or scapula (shoulder blade).
Osteochondroma is the most common benign (non-cancerous) bone growth. The lesion usually occurs during skeletal growth - between the ages of 10 and 25 years. It affects males and females equally. This condition affects males and females equally in their first decade, and is found in the lower femur, upper tibia and upper humerus i.e. the metaphysis of long bone. The condition can be single or multiple, the later is associated with a 20% rate of malignancy, compared to less than 1% in the presence of a solitary tumour.
While the exact cause of osteochondroma is not known, there is a genetic link, indicating that there is a form of the disorder that is inherited. There is also a non-inherited form of the disorder. An osteochondroma occurs at any growth plate in the body (a cartilage layer in the end of children's bones where growth occurs) and leads to a "bump" or "lobule" which grows on the surface of otherwise normal bone. The lesion basically results from a flaw in growth and can almost be thought of as a "birthmark" that you can't see from outside the body. There is one condition called "multiple osteochondromatosis" in which a child can have many lesions at the same time. This is usually inherited.
Osteochondromas are most often seen in the second or third decade of life, although they are thought to be congenital lesions arising from displaced or aberrant growth plate cartilage. They may also arise in children with open growth plates who have been irradiated. What a child feels depends on the size and location of the tumor. In general, they are hard and are part of the bone. The only time that they cause pain is when nerves, muscles, tendons (the attachment of muscle to bone), or ligaments rub against them. This is more common in larger lesions. It is common to see one by accident on an x-ray that a physician orders for a unrelated reason. Many adults find out that they have had an osteochondroma during their whole life in this fashion.
Treatment for osteochondromas varies significantly depending on the size of the overgrowth and the symptoms of the individual. Treatment may include surgery (to remove the mass) and medications (to control pain). If there is no sign of bone weakening or increased overgrowth, observation only may be suggested. Careful follow-up with a physician to monitor bone growth may be recommended.