 Osteoid Osteoma
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An osteoid osteoma is a benign, bone-forming tumor that occurs most often in the long bones of the lower extremities. The femur (thighbone) is the most common location of occurrence, although it can emerge in the bones of the hand and it sometimes occurs in the lower part of the spine.
Osteoid osteomas are very small tumors that do not grow larger that half an inch in diameter. They usually emerge sometime during the teenage years or early adulthood. The condition seems to occur more often in males than females.
These tumors, while causing painful symptoms, typically do not progress or harm the host bone, although in young children, those located near a growth plate, may deform the host bone, or stimulate the bone to grow larger or longer. They do not, however, metastasize (spread) beyond the bone. If located near a joint, they may be associated with swelling or fluid in the joint.
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An osteoid osteoma occurs when certain cells divide uncontrollably, forming a small mass comprised of bone and other tissue. This growing tumor replaces healthy bone tissue with abnormal, hard bone tissue. No one knows exactly why this occurs.
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The following are the most common symptoms of an osteoid osteoma. Keep in mind that each individual may experience symptoms differently:
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Dull or sharp pain that worsens at night
- Pain that is usually relieved by aspirin or other anti-inflammatory drugs
- Limping
- Painful scoliosis and muscle spasticity (when tumor is located in the spine)
- Growth disturbance (when tumor is involved with a bone's growth plate)
- Muscle atrophy
- Bowing deformity
- Nerve symptoms (like sciatica) when located in the spine
The signs and symptoms of osteoid osteoma may resemble other medical conditions or problems. Occasionally children with undiagnosed osteoid osteomas have been thought to have a psychological or psychiatric condition. Always consult a physician for a diagnosis.
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In addition to taking a complete physical and performing a full medical examination, your child's doctor may use any of the following tests (alone or in combination) to diagnose osteoid osteoma:
- X-rays - a diagnostic test that uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.
- Computerized Tomography scan (also called CT or CAT scan) - a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices) both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat and organs. This test is also particularly useful in identifying tumors located in the spine, which are difficult to image on a plain x-ray.
- Magnetic Resonance Imaging (MRI) - a diagnostic procedure that uses a combination of large magnets, radiofrequencies and a computer to produce detailed images of organs and structures within the body. This test is particularly useful in identifying tumors in areas that are difficult to image on a plain x-ray, such as the spine. However, in diagnosing osteoid osteoma, a CT scan (described above) is preferred over an MRI.
- Bone scan - a nuclear imaging method to evaluate any degenerative and/or arthritic changes in the joints; to detect bone diseases and tumors; to determine the cause of bone pain or inflammation.
- Complete blood count (CBC) - a measurement of size, number and maturity of different blood cells in a specific volume of blood
- Blood tests - (including blood chemistries)
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Specific treatment for an osteoid osteoma will be determined by your child's physician based on:
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your child's age, overall health, and medical history
- extent of the disease
- your child's tolerance for specific medications, procedures, or therapies
- how your child's physician expects the disease may progress
- your opinion or preference
Treatment for osteoid osteoma traditionally involved an operation to remove the tumor performed by an orthopaedic surgeon. More recently, many osteoid osteomas have been treated by the radiologist using the technique known as percutaneous radiofrequency ablation. This is a minimally invasive procedure in which radio frequencies are passed beneath the skin through a needle to kill the tumor cells by heating them to a high temperature. This technique is performed by the radiologist in a CT scan under general anesthesia. The advantage is that this is a day procedure that does not significantly weaken the bone. It quite successfully cures the tumor and relieves the pain and has much less morbidity than an operation. This method cannot be used to treat tumors of the spinal column, but in other locations has largely replaced operations.
In some cases, if the doctor determines that heat ablation cannot be used to treat your child's osteoid osteoma (i.e. if the tumor is in the spinal column) than your child may need an operation. In most cases, surgery alone, without complimentary therapies, is all that is necessary. The following surgical procedures are among those used to treat osteoid osteoma:
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Curettage: Most osteoid osteoma that are surgically treated are treated by curettage to remove only the tumor. Curettage is an operation during which the tumor is scraped out of the bone with a special instrument called a curette that has a scoop, loop or ring at its tip. For this procedure, surgeons make an incision in the bone to create a window. Sometimes special imaging techniques (such as bone scans) are needed to locate the tumor in the operating room. The tumor is completely curetted and the remaining cavity is then packed with donor bone tissue (allograft), bone chips taken from another bone (autograft), or other materials depending on the preference of the surgeon.
- En bloc resection: If more aggressive resection of the tumor is warranted (not typically the case in osteoid osteoma), the operation will likely involve en bloc resection, which is the surgical removal of bone containing the tumor, with wide margins of healthy tissue surrounding the tumor. This type of operation is seldom performed today.
- Internal fixation: The use of metal rods or pins in reconstruction of the bone after the tumor is excised.
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Prognosis for an osteoid osteoma is generally excellent, although prognosis varies from individual to individual depending on:
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how active the tumor is
- the tumor's response to therapy
- the age and overall health of your child
- your child's tolerance for specific medication, procedures or therapies.
Most of these tumors can be successfully treated. However, recurrence can occur. Continuous follow-up care is essential for the successful treatment of an osteoid osteoma. A schedule of follow-up care should be determined by your child's physician and other members of your care team to monitor ongoing response to treatment and possible late effects of treatment.
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