About multiple osteochondromatosis

What is multiple osteochondromatosis?

Hereditary multiple osteochondromas (HMO) is a rare genetic disorder characterized by multiple benign (noncancerous) bone tumors that are covered by cartilage (osteochondromas), often on the growing end (metaphysis) of the long bones of the legs, arms, and digits. These osteochondromas usually continue to grow until shortly after puberty and may lead to bone deformities, skeletal abnormalities, short stature, nerve compression and reduced range of motion. Hereditary multiple osteochondromas is inherited as an autosomal dominant genetic condition and is associated with abnormalities (mutations) in the EXT1or EXT2 gene.

Hereditary multiple osteochondromas was formerly called hereditary multiple exostoses.

What are the symptoms for multiple osteochondromatosis?

Hereditary multiple Osteochondromas is a rare disorder that affects bone growth. Bony tumors (exostoses or osteochondromas), covered with cartilage, typically appear in the growth zones (metaphyses) of the long bones adjacent to the areas where tendon and muscles attach to the bone. These growths vary in size and number among affected individuals, even within the same family. Some individuals will present with a few large “lumps” while others will show several small growths. The median age of diagnosis is three years and almost all affected individuals are diagnosed by 12 years of age.

In many cases, no treatment is required. If the exostoses are small, they may have little or no effect on the patient. However, in more severe cases, the growths may cause deformities of the forearm, knees, ankles, spine and/or pelvis. They may impose upon nerves, tendons and/or blood vessels, and interfere with movement or circulation, causing substantial Pain as a result of pinched nerves or compressed tendons.

Bones that develop exostoses most often are the upper arm (humerus), forearm, knee and shoulder blades (scapulae). Bowing of the forearm and ankle are the problems that most often require surgical correction.

Approximately 40 percent of affected individuals have Mild Short stature as a result of shortened and/or bowed legs. If the vertebrae are affected, spinal cord compression may result, causing Numbness and/ or paralysis. Urinary obstruction has been observed due to exostoses of the pelvic area.

The bony growths that characterize this disorder continue to grow until shortly after puberty at which time normally new growth no longer develops. The risk for development of malignant (cancerous) tumors, mostly chondrosarcomas, is approximately 1 to 5%.

What are the causes for multiple osteochondromatosis?

Hereditary multiple osteochondromas is inherited as an autosomal dominant genetic condition. Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary to cause a particular disease. The abnormal gene can be inherited from either parent or can be the result of a new mutation in the affected individual. Approximately 10% of cases of HMO are thought to be the result of new mutations. At present two genes, EXT1 and EXT2, are known to show mutations in HMO patients and it is thought that these genes function as tumor suppressors. For some affected individuals no mutation in either gene is detected. In almost all these cases, the “mutation negative” patients do not have a familial history for exostoses. Most likely, they have an EXT1 or EXT2 mutation in only part of their body cells and the mutation is absent or undetectable in blood cells, which are usually used for DNA analysis. Data indicates that individuals with EXT1 mutations may have more severe effects than those with EXT2 mutations. The risk of passing the abnormal gene from affected parent to offspring is 50% for each pregnancy. The risk is the same for males and females.

What are the treatments for multiple osteochondromatosis?

Surgery may be required to relieve pain, improve movement, restore normal circulation, or for cosmetic reasons. Malignant degeneration of a tumor is treated surgically, possibly in combination with chemotherapy and radiation therapy.

Most of the malignant degenerations to cancers are to cartilage tumors or chondrosarcomas, which are slow growing and generally insensitive to chemotherapy.

Monitoring the size of affected bones by annual scans to screen for malignant degeneration is sometimes recommended. Rapid growth and increased pain are signs of a possible malignant change.

Genetic counseling is recommended for affected individuals and their families. Other treatment is symptomatic and supportive.

What are the risk factors for multiple osteochondromatosis?

The prevalence of HMO has been estimated to be about 1 of 50,000 live births. A high prevalence of this disorder has been reported in some isolated communities. Hereditary multiple osteochondromas is a disorder that affects males and females in equal numbers but in general males tend to be more severely affected.

Is there a cure/medications for multiple osteochondromatosis?

There is no cure for multiple osteochondromatosis, but There are many medications that can be used to treat multiple osteochondromatosis, but it is important to speak with your doctor about what is right for you. Here are some of the most common medications:

1. Pain relievers: These include acetaminophen (Tylenol) and nonsteroidal anti-inflammatory drugs such as ibuprofen (Advil).

2. Immunosuppressants: These help reduce the body's response to an infection or disease. Immunosuppressants may be prescribed if your osteochondromatosis causes an infection or inflammation.

3. Steroids: These are hormones produced by the adrenal glands that have anti-inflammatory properties. Steroids may be prescribed if your osteochondromatosis causes inflammation or infection in the joints or bones.

4. Antibiotics: These treat bacterial infections and fight against harmful microbes that cause illness in humans. Antibiotics may be prescribed if your osteochondromatosis causes an infection in a joint or bone that has been damaged by excessive growths of bone cells called osteophytes (or "spurs").

5. Bisphosphonates (Fosamax, Actonel), which also help to reduce bone pain and increase bone density; these are prescribed by your doctor based on your risk of fracture and the results of a DEXA scan.

6. Pamidronate (Aredia), which is used to treat severe osteoporosis in people with multiple osteochondromatosis; it works by increasing bone strength and reducing the risk of fractures.

Pain and swelling in weight-bearing joints, such as the knee or ankle,Pain in joints that aren't weight-bearing, like the shoulder or hip,Bone deformities like bowing of the legs and a curved spine,A bump on your skin that feels like a bone, often near the joint where it hurts most.
Traumatic injury to the knee,Ingestion of high doses of vitamin D,Hyperparathyroidism,Hyperthyroidism,Osteomalacia (softening of the bones).

Video related to multiple osteochondromatosis