Osteochondroma

Osteochondroma is the most common noncancerous bone growth and most often develops during childhood and adolescence between the ages 10 and 30. It is an overgrowth of cartilage and bone at the end of the bone near the growth plate, usually affecting the long bones in the leg, pelvis or shoulder blade.

Types & Stages

Osteochondromas are generally divided into three types:

• Solitary. This is the most common form, where only one bone lesion is present. Since it isn't cancerous, it doesn't spread to other parts of the body. 
   
• Multiple. This type tends to involve multiple growths on the bone. They occur in about 15 percent of cases and are usually the result of a genetically inherited condition called hereditary multiple osteochondromas or hereditary multiple exostoses. But they can also occur at random (about 30 percent of the time). Multiple osteochondromas are also noncancerous, but they pose a greater chance of complications, usually by interfering with the normal growth of bones.
   
• Multiple hereditary exostosis (MHE). Also called hereditary multiple osteochondromas, like a solitary osteochondroma, MHEs are all continuous with the underlying bone and end with a cartilage cap and bursa.

Osteochondromas, whether single or multiple, also have different growth patterns that can be described as pedunculated (a narrow stalk of bone) or sessile (broad base of bone).

Signs & Symptoms

Symptoms of osteochondromas can include:

• a hard, painless mass that doesn’t move
• lower-than-normal-height for your age 
• one leg or arm that is longer than the other
• pressure or irritation with exercise
• soreness in nearby muscles

Diagnosis

Tests and procedures used to diagnose osteochondromas include: 

• X-rays. Most osteochondromas will show up on an X-ray, a diagnostic test that uses invisible electromagnetic energy beams to produce images of internal tissues, bones and organs onto film. If further detail is needed, they might also require:  
   
• Computerized tomography scan (CT or CAT scan). A diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. 
   
• Magnetic resonance imaging (MRI). A diagnostic procedure that uses a combination of large magnets, radiofrequencies and a computer to produce detailed images of organs and structures within the body. 

Treatment

Treatment for osteochondroma includes:

• Regular monitoring. Your doctor may want to take periodic X-rays to keep track of its growth and they'll also want to know if it's causing any pain or functional problems by putting pressure on nearby tissues, blood vessels or nerves. 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. 
   
• Surgery. To completely remove an osteochondroma, your surgeon will perform a surgical procedure called excision. In an excision, all of the tumor and an area of surrounding tissue are removed. In the procedure, the tumor will be removed at the level of the normal bone. In some cases, they may recommend additional surgery to realign the bones.

Causes and Risk Factors

The cause of osteochondroma is unknown. Risks might include:

• Bone abnormality. The tumor is thought to be related to an abnormality in the growth plate, causing a bony prominence to grow away from the bone.
   
• Genetic disorder. If a child has several osteochondromas, they are usually the result of a genetic disorder known as multiple hereditary exostoses (MHE) or multiple osteochondromas. However, there is also a non-heredity form of MHE in which multiple osteochondromas occur by chance (sporadically).

Screening

There is no routine screening test for osteochondroma.