An osteochondroma is an abnormal, noncancerous growth on the bone surface near the growing ends of long bones in children and adolescents. It is made up of cartilage and bone and may be attached to the underlying bone by a stalk (pedunculated) or a broad base (sessile). Osteochondromas usually stop growing at skeletal maturity on reaching adulthood and in most cases no treatment is required. They are thought to be caused by a genetic abnormality and are usually inherited.
Osteochondromas may be solitary or multiple. Solitary osteochondromas are usually seen in the joints of the shoulder, hip, and knee. Multiple osteochondromas also referred to multiple osteochondromatosis may cause deformities of the knees, ankles and forearms as well as a shortened stature.
An osteochondroma may occur as a painless swelling near a joint. If it impinges on a tendon there may be pain with movement of the joint or a snapping sensation. Impingement on a blood vessel may result in loss of color or pulsation to the limb. Acute pain and swelling may occur if the stalk of a pedunculated osteochondroma is broken due to an injury. Symptoms of multiple osteochondromatosis are severe compared to a solitary osteochondroma.
An osteochondroma is diagnosed based on your symptoms as well as a physical examination of the painful area. Your doctor will palpate the outgrowth and check the range of motion of the joint. X-rays may be ordered to detect bony abnormality. An MRI will give a more detailed picture of the area as well as any soft tissue abnormality. Any suspicion of malignancy can be ruled out by a biopsy of the lesion. Multiple osteochondromatosis lesions have a greater risk of becoming cancerous in which case a CT scan of the chest to identify any metastasis may also be required.
If the osteochondroma is not causing any pain or loss of function, a wait-and-watch approach with regular x-rays is usually sufficient. Surgical treatment is indicated if there is pain, impingement of surrounding nerves or blood vessels, or a large cartilaginous cap over the outgrowth suggesting cancerous change. The surgery involves excision of the tumor to attain normal bony contour. If the lesion becomes cancerous, surgical removal of the tumor in combination with chemotherapy and radiation may be required.