An osteoblastoma is a benign tumor of any bone. At The Spine Hospital at The Neurological Institute of New York, we specialize in spinal osteoblastomas.
Osteoblastomas arise from osteoblasts, one of the two main cell types present in all bones. Osteoblasts form new bone, while osteoclasts break down existing bone. Osteoblasts and osteoclasts work in concert to repair and remodel bones throughout a person’s lifetime.
In an osteoblastoma, however, the osteoblasts malfunction. They proliferate in an uncontrolled manner and haphazardly produce new bone tissue. The bone tissue produced by an osteoblastoma is abnormal and much weaker than normal bone. Osteoblastomas can grow to be quite large.
About 40% of osteoblastomas occur in the vertebrae, or bones of the spine.
Though benign (noncancerous), spinal osteoblastomas can cause severe symptoms.
Osteoblastomas destroy normal vertebral bone and replace it with weak, abnormal bone. This process sometimes causes aching pain that is not relieved with NSAIDs (nonsteroidal anti-inflammatory drugs, like aspirin). Most spinal osteoblastomas occur in the posterior (rear) sections of the vertebra, but tumors that affect the weight-bearing anterior (front) section of the vertebra can make the weakened vertebra vulnerable to compression fracture.
Spinal osteoblastomas may cause muscle spasms that produce scoliosis, or a bending and twisting of the spine. Scoliosis caused by muscle spasm is generally painful.
As they grow, spinal osteoblastomas may also impinge on nearby structures like the spinal cord or nerve roots, damaging those delicate tissues. This may produce pain that radiates into the arms or legs; weakness, numbness, or clumsiness in the arms and legs; or a loss of bowel and bladder control.
Causes and Risk Factors
Osteoblastoma is a rare tumor, and its causes are not yet understood. It is more common in males than females, and equally common across races. Most people diagnosed with osteoblastoma are in the second and third decades of life.
Tests and Diagnosis
Diagnosing osteoblastoma can be a challenge. Osteoblastomas are very similar to the more aggressive osteosarcoma and the less aggressive osteoid osteoma. Each tumor type follows a different course and is treated differently.
In many cases, the diagnosis of osteoblastoma is suggested by the tumor location, size, and appearance on X-ray. A definitive diagnosis usually requires a biopsy, a procedure in which part of the tumor is removed for study in a laboratory.
CT (computed tomography) scans use a combination of X-rays and computer technology to produce detailed images of bones and soft tissues. CT scans can localize the tumor more precisely than a plain X-ray, which is helpful in surgical planning.
MR (magnetic resonance) scans use magnets, radio waves, and computer technology to produce images of organs and tissues like the brain and spinal cord. These scans can reveal the tumor’s involvement with nearby nerve roots or other soft tissues.
Surgery is the treatment of choice for osteoblastoma. The goal of surgery is complete excision of the tumor. This is a more difficult process for osteoblastomas in the spine than in other locations, as it may not be possible to safely remove the entire tumor. However, the outcome for most patients is very good.
Most osteoblastomas occur in the vertebral arch, at the posterior (rear) of the spine. A laminectomy is performed to remove the tumor. Instrumented spinal fusion may need to be performed in some patients to maintain spinal stability.