Osteopetroses are a group of rare disorders that increase the density of bones.

• These disorders occur when the body does not recycle old bone cells.
• Typical symptoms include impaired bone growth and thick bones that easily break.
• The diagnosis is based on symptoms and x-rays.
• Osteopetrosis that occurs in infancy is fatal if not treated.
• There is no cure, but some treatments can help relieve problems caused by the disorder.

In osteopetrosis (sometimes called marble bones), the body does not recycle old bone cells. The result is increased density or thickness of the bones and an alteration in how the bones are shaped. These changes make bones weaker than normal. The dense bone tissue also crowds out the bone marrow, which is where blood cells are formed.

Osteopetroses range from mild to severe and can even be life threatening. Symptoms may begin in infancy (early onset) or later in life (delayed onset).

Symptoms and Diagnosis

Although osteopetroses are different disorders, many of the same symptoms develop in most of them. Bone growth is usually impaired. Bones thicken and break easily. Formation of blood cells may be impaired because there is less bone marrow, leading to anemia, infection, or bleeding. Overgrowth of bone in the skull can compress nerves, causing facial paralysis or loss of vision or hearing, and can distort the face and teeth.

Doctors usually base the diagnosis on symptoms and on x-rays that show very dense bone. When the person has no symptoms, osteopetrosis is sometimes detected only by chance, after a doctor sees very dense bones on x-rays taken for an unrelated purpose.

Prognosis and Treatment

Early-onset osteopetrosis that is not treated with bone marrow transplantation usually causes death during infancy or early childhood. Death usually results from anemia, infection, or bleeding. Late-onset osteopetrosis is often very mild.

There is no cure. Corticosteroids, such as prednisone, decrease the formation of new bone cells and may increase the rate of removal of old bone cells, strengthening bones. Bone marrow transplantation seems to have cured some infants with early-onset disease. However, the long-term prognosis after transplantation is unknown.

Fractures, anemia, bleeding, and infection require treatment. If nerves going through the skull are compressed, surgery may be required to take pressure off the nerves. Orthodontic treatment may be needed to correct distorted teeth.

Last full review/revision February 2008 by Frank Pessler, MD, PhD; David D. Sherry, MD