It is a benign tumor made up of bones that is usually less than 2 cm in size.
It consists of a central vascularized nest that represents the neoplastic tissue and this is surrounded by normal reactive bone.
Usually it is a single injury that is very painful. The nest microscopically resembles the same type of tissue as an osteoblastoma.
Osteoma Signs and Symptoms
Symptoms of the condition include:
- Progressive pain that is significantly relieved by aspirin or an NSAID (very rarely, less than 1%, may be painless). This discomfort is usually worse at night.
- Nearby tumors can increase growth and cause skeletal asymmetry.
- Epiphyseal injuries can cause joint effusion and a clinical picture similar to rheumatoid arthritis .
- Spinal injuries can cause muscle spasm scoliosis.
- Men are more commonly affected than women.
- Osteoma is most common in the second decade of life.
- 75% -80% of patients are between the ages of 25 and rarely over the age of 30.
Places of affection
Its appearance is more frequent in the facial or cranial area.
There is also the osteoid osteoma that develops in the femoral neck, but it can occur anywhere within a bone (metaphyseal, diaphyseal, epiphyseal, cortical, medullary and periosteal), 50% occur in the long bones of the lower extremities.
Most osteomas are intracortical in origin, but can also occur in the medullary or subperiosteal canal.
What Causes an Osteoma?
The osteoma can be generated by the active increase of the bone in an abnormal way that is generated by encapsulation.
This growth can also be generated by a trauma or contusion in the affected area, which develops slowly and being in some cases asymptomatic, it is detected when the growth is visibly noticeable or fortuitously during a general medical check-up.
When the presence of an osteoma is suspected, the following can be performed:
An x-ray study to detect if the affected area is surrounded by marked sclerosis or if mineralization or ossification is shown, usually from the center outward that appears as a central zone of density.
This type of heavily ossified condition can be mistaken for the surrounding sclerosis and difficult to detect on a plain X-ray.
Cortical and subperiosteal osteoid osteomas are generally associated with much more reactive sclerosis than spinal tumors.
The periosteal reaction is continuous and often appears as cortical thickening (benign-onset reaction).
Intracapsular osteoid osteomas are difficult to identify because there is no periosteum in the intracapsular region and therefore a periosteal reaction does not occur.
Double density signs can be detected with radiography because warmth within the nest and less intense accumulation peripherally within the sclerotic bone can be seen.
MRI should be performed with gadolinium if possible, because an osteoma on MRI can mimic the findings of a malignant tumor such as Ewing’s sarcoma or osteomyelitis due to the presence of bone marrow and soft tissue edema that may be extensive and difficult to discern.
Magnetic resonance imaging is good for detecting synovitis and joint effusion with osteoid joint osteomas.
Osteomas exhibit limited growth potential to a certain size and then stop growing; some tumors can return spontaneously.
Osteoid osteomas that occur adjacent to the joints can cause the adjacent synovium to thicken and there may be infiltrates of chronic inflammatory cells with lymphoprolytic features in the synovium that can be mistaken for rheumatoid arthritis.
Currently, most osteomas are amenable to CT-guided percutaneous radiofrequency ablation (radiofrequency ablation).
This is a minimally invasive technique in which the patient undergoes general anesthesia and the nest is located under a CT scan. A needle is attached and the nest is then burned by radio frequency waves.
It is more than 90% successful and there are minimal risks. Most patients find that the pain disappears the next day. There is little downtime, and most sufferers return to normal activities within a day or two.
Some patients may require an open surgical excision or “burr reduction resection” of the osteoid osteoma.
This is a benign tumor and there is no risk of metastasis , radiofrequency ablation is effective more than 90% of the time.
The results of radiofrequency ablation are better than those reported with surgical excision and there is less morbidity and possible complications.
The osteoma can be difficult to identify easily, especially in intracortical sclerotic regions.
Osteoid osteoma of the extremities can cause nearby muscle atrophy, if it becomes radiographically undetectable, the patient can be erroneously treated for arthritis.