Osteopetroses
The osteopetroses are a group of rare disorders that increase the density of bones.
In osteopetroses (sometimes called marble bone diseases), the body fails to recycle old bone cells. The result is increased density of the bones. The increased density makes bones weaker than normal. The dense bone tissue also crowds out the bone marrow.
The 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).
Although the 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 of a lack of bone marrow, leading to anemia, infection, or bleeding. Bone overgrowth in the skull can compress nerves, causing facial paralysis or loss of vision or hearing, and can distort the face and teeth.
Doctors usually establish the diagnosis based on the symptoms and the appearance of very dense bone on x-rays. 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.
Treatment and Prognosis
There is no cure. Corticosteroids, such as prednisone, decrease formation of new bone cells and may increase the rate of removal of old bone cells, strengthening bones. Bone marrow transplantation appears 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 leaving the skull are compressed, surgery may be required to release the nerve. Orthodontic treatment may be needed.
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.
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