• What is osteoblastoma?

    Osteoblastoma is a rare benign bone tumor that accounts for about 1 percent of all primary bone tumors in the United States. It affects twice as many boys as girls.

    While most primary bone tumors form in the extremities, osteoblastoma usually forms in the lower vertebrae of the spine or in the long bones of the leg. It can also occur in any of the bones in the arm, hands, legs and feet.

    Osteoblastoma is difficult to diagnose because it can manifest in different ways — as a slow-growing tumor or as a more aggressive tumor that invades surrounding tissue and bone. The more aggressive form of osteoblastoma may mimic the signs and symptoms of osteosarcoma, a cancerous tumor which is 20 times more common than osteoblastoma. It may also occur in conjunction with aneurysmal bone cysts, another benign tumor.

    Osteoblastoma is also closely related to osteoid osteoma, a more common benign bone tumor, but differs in that an osteoblastoma can grow larger than an osteoid osteoma.

    If an osteoblastoma is located on or in the spinal column, it can cause scoliosis and neurological symptoms.

  • Causes

    It is not known what causes osteoblastoma.

  • Signs and symptoms

    Symptoms of osteoblastoma include:

    • Sustained pain (which is less likely to respond to over-the-counter common pain relievers like Tylenol or ibuprofen)
    • Swelling and tenderness
  • Testing and diagnosis

    The clinical course of osteoblastoma can make it difficult to diagnose. It can present as a slow growth or an aggressive growth, and its symptoms and clinical and radiographic features can be confused with osteoid osteoma, giant cell tumor, fibrous dysplasia and osteosarcoma.

    A careful examination is necessary for an accurate diagnosis of osteoblastoma.

    At The Children’s Hospital of Philadelphia (CHOP), your child's diagnostic evaluation begins with a thorough medical history and physical examination of your child.

    Clinical experts use a variety of diagnostic tests to diagnose osteoblastoma, including:

    • X-rays, which produce images of bones and internal organs on film.
    • Radioisotope bone scan, which can help determine an area of abnormal bone growth. 
    • Magnetic resonance imaging (MRI), which uses a combination of large magnets, radiofrequencies and a computer to produce detailed images of organs and structures within the body.
    • Computed tomography (CT) scan, which uses a combination of X-rays and computer technology to produce cross-sectional images ("slices") of the body.
    • Biopsy, which is a short surgical procedure to take a large sample of the growth, may be necessary to confirm any findings.
    • Angiography, a radiograph-type X-ray test which reveals the inside of blood vessels and organs.
    • EOS imaging, an imaging technology that creates 3-dimensional models from two planar images. Unlike a CT scan, EOS images are taken while the child is in an upright or standing position, enabling improved diagnosis due to weight-bearing positioning.
  • Treatments

    Surgically removing the tumor is usually the recommended treatment for osteoblastoma.

    At Children’s Hospital, we generally use a surgical procedure called intralesional curettage, to scrape out the bone to completely remove the tumor and fill the space with bone graft material.

    Though surgery is highly effective, we understand that any surgery can be a stressful experience for your child and family. At CHOP, we offer a wealth of resources about how to prepare your child for surgery and what to expect during surgery.

    Additionally, we employ numerous best practices before, during and after surgery to decrease the risk of infection and increase positive outcomes. See safety in surgery for details about safety protocols at The Children's Hospital of Philadelphia.

  • Follow-up care

    At CHOP, we offer ongoing support and services for your child and family at our Main Campus and throughout our CHOP Care Network. Our team is committed to partnering with parents and referring physicians to provide the most current, comprehensive and specialized care possible for your child.

    If your child had surgery for osteoblastoma, he or she will return for check-ups one to two weeks after surgery, then again at three months, six months and one year post-surgery.

    As with other tumors, it is important for your child to see a physician regularly for check-ups to monitor the area in case the tumor should return.

    For children with osteoblastoma that leads to scoliosis or other curvature of the spine, additional treatment may be necessary.

  • Outlook

    Osteoblastoma has a recurrence rate of about 10-20 percent, especially if the tumor was not able to be completely removed during surgery.

    Long-term outcomes for children with osteoblastomas are good. There are no reported cases of osteoblastomas transforming into malignant tumors.

Reviewed by Jason L. Katz, PA-C, MHS, ATC-R on May 19, 2014