Osteochondroma is a benign (noncancerous) tumor that grows slowly and usually begins near the ends of long bones. It may be identified at any age, though it typically develops during childhood as the bone grows. Once the child stops growing, the osteochondroma also stops growing, but remains in place. Because this tumor is benign, it usually does not pose a significant risk or concern, and often can be left untreated. The disease is thought to affect approximately one to two percent of the population, though many cases are undiagnosed, so its true prevalence may be greater.
The most common time for osteochondroma to be diagnosed is during a child’s large growth spurts. For unknown reasons, it is usually more prominent in males. Females who have this disease tend to contract it slightly earlier, due to earlier adolescence. This tumor consists of a stalk of bone growing away from the nearby growth plate, which is covered by a thin cap of cartilage. On occasion, the osteochondroma can become painful, may fracture or may press upon nerves or tendons. Rarely, an osteochondroma may transform into a malignancy (cancer) such as chondrosarcoma, which generally manifests as growth or discomfort after the child reaches adulthood.
The bone is a complex part of the human body. It consists of the following:
- Articular cartilage – The hard cartilage at the head of the bone
- Periosteum – The covering of the compact and cortex of the compact bone
- Cancellous tissue – The spongy part of the bone
Bones do more than simply shape the body and act to help stabilize it during motion. At the ends of bone are growth plates, known as physes. Most of the growth in bone length comes from these physes. The formation of an osteochondroma is thought to result from an abnormality associated with physis development during growth.
Usually, the symptoms of osteochondroma are fairly minor, and in many cases the child does not experience any at all. However, because of the small risk of an osteochondroma turning malignant, it is always a good idea to visit a physician for examination.
The following are common osteochondroma symptoms. Keep in mind that everyone’s body is different and may experience only some or none of these:
- A painless bump near a joint
- Snapping sensation of overlying tendons
- Fracture of an osteochondroma
- Pain if the tumor is pressing on a nerve ending
Osteochondroma symptoms are typically felt only if the tumor is pressing against another structure, such as a nerve or a tendon. Otherwise, the biggest sign is a small painless mass. In any case, it is always important to see a doctor to determine whether the tumor is benign.
There are many causes of osteochondroma, including:
- Inherited from a family member – Often seen with multiple osteochondromas, in a condition known as multiple hereditary osteochondromas (or multiple hereditary exostoses). These frequently are identified earlier during childhood.
- Age – Osteochondromas develop during childhood or adolescence, though they may not be noticed until adulthood. Any continued growth of the tumor into adulthood should warrant a detailed investigation.
- Previous radiation – Children who have been treated using radiation are at a slightly increased risk of developing a tumor. The reason for this is not entirely understood.
Osteochodroma can be divided into two main categories:
- Solitary osteochondroma – This is the most common form of this type of tumor and forms on only a single bone in the body. These osteochondromas may account for up to 35 to 40 percent of all benign bone tumors.
- Multiple osteochondromas – More than one occurrence of osteochondroma. Most of the time, multiple occurrences are inherited in a condition called multiple hereditary osteochondromas (or multiple hereditary exostoses); only 30 percent of the time do they appear randomly. Patients with this condition often have alterations in the growth of their long bones and have an increased risk of developing a chondrosarcoma in one of the tumors.
The multidisciplinary team of musculoskeletal oncology experts at Northwell Health Orthopaedic Institute treats osteochondroma as well as a broad range of conditions that affect the bones.