Solitary osteochondromas are thought to be the most common non-cancerous (benign) bone tumor resulting from a developmental abnormality of bone. It occurs when part of the growth plate forms an outgrowth on the surface of the bone. They become cancerous much less than 1% of the time.

Multiple osteochondromatosis is diagnosed when two or more osteochondromas are seen on plain X-rays. About 70 percent of the time, it is inherited. About 30 percent of the time, it occurs randomly. A patient may also have deformities of the forearms, a short stature, and knock-knees and ankles. This is caused by abnormal growth in the bones affected by the osteochondromas. These can become malignant about 1% of the time with large tumors.

How are osteochondromas diagnosed?

Plain x-ray – Will show the bony growth with a stalk (pedunculated) or without a stalk (sessile)

Computed tomography (CT) scan – Used to look for cartilage on the surface of the bony growth or the lesion continuous with the bones outer shell (cortex)

Common presenting symptoms

  • Painless bump near the joints (most commonly knee and shoulder)
  • Found at the ends of any long bone, and along the pelvic and shoulder bones
  • If the stalk of a pedunculated osteochondroma breaks, pain and swelling may start immediately
  • Located under a tendon causing snapping of the tissue over the tumor may cause activity-related pain

Treatment Options

Observation – Most of the time, solitary osteochondromas are not removed surgically. The doctor will carefully observe it. He or she may want to take regular X-rays to keep track of any changes.

Surgical – Surgery is recommended when growth is complete (a mature skeleton by X-ray evaluation) before removing. This decreases the chance of the tumor growing back. The osteochondroma is removed at the level of the normal bone. Some of the inside of the bone may also be removed.

Surgery may be considered when:

  • There is pain with activity
  • There is pressure on a nerve or blood vessel

How will my child do in the long run with an osteochondroma?

Children usually do really well. If the tumor does not cause a lot of pain, it can be left alone for life. Also, it is important to note that an osteochondroma stops growing when a child reaches skeletal maturity (i.e. when he/she stops growing.)