Osteoblastoma

Osteoblastoma is a type of benign bone tumor. It’s not cancerous, but it can cause changes in your bones. The tumor attacks your healthy bone tissue and creates a new kind of tissue called osteoid. Osteoid is weaker than healthy bone tissue, so it weakens your bones and makes them more prone to fractures. Osteoblastomas may also cause symptoms as they grow bigger, like pain or swelling.

Where does osteoblastoma occur?

Osteoblastoma can grow in any bone, but it's most common in your spine. Up to 40% occur there.

It may also occur in your:

• Legs or feet
• Arms or hands
• Jawbone
• Ribcage
• Collarbone
• Breastbone

Symptoms of osteoblastoma

The most common symptom of osteoblastoma is bone pain — a dull, aching type of pain that seems to come from deep in your body. You might also see a lump or swelling under your skin that’s tender to touch. An osteoblastoma in one of your legs or feet might cause a limp or change the way you walk.

As the tumor grows bigger, it might cause additional symptoms. The average size of an osteoblastoma is 4 centimeters (cm), which is about the size of a cherry tomato. But some have been known to grow twice or even three times as big. A larger tumor might compress a nearby nerve, causing nerve-related symptoms, like:

• Nerve pain
• Numbness, weakness or tingling in your limbs
• Back pain or neck pain (from a spinal osteoblastoma)
• Muscle spasms

Complications of this condition

An osteoblastoma that grows too much may cause complications, including:

• Bone destruction. It can weaken and destroy healthy bone tissue, making it easy to injure.
• Secondary tumors. Sometimes, aneurysmal bone cysts occur as a side effect of osteoblastoma.
• Nerve compression. An osteoblastoma that compresses a nerve may cause neuropathy.
• Scoliosis. An osteoblastoma in your spine can cause temporary curvature (scoliosis).

Other rare complications of osteoblastoma might include:

• Toxic osteoblastoma. Very rarely, osteoblastoma appears to have caused a widespread inflammatory reaction in some people. This is called toxic osteoblastoma. It causes inflammation in the membrane around your bones (periosteum), along with fever and weight loss.
• Malignant transformation. Although osteoblastoma is a benign tumor, it has very rarely been reported to transform into a cancerous one. However, this possibility is controversial. Some experts argue that when this happens, the tumor was actually osteosarcoma all along.

Risk factors

Healthcare providers don’t know what causes osteoblastoma. But they have observed that it tends to occur in younger adults (under age 30). It’s also twice as common in males as it is in females.

How doctors diagnose this condition

A healthcare provider will start by discussing your symptoms and health history. Then, they’ll physically examine the sore or swollen spot. They’ll follow up with imaging tests, starting with X-rays. Depending on what the X-rays show, they might want to order more detailed imaging tests, like a CT scan or MRI. These can help locate the tumor and show how it’s affecting your surrounding tissues.

Your provider will often recognize osteoblastoma by its appearance on imaging tests. But they may need to take a tissue sample (biopsy) to confirm it. Once they’ve located the tumor, they can take the sample with a biopsy needle or with a small incision. They’ll send it to a pathology lab to analyze. A process called immunostaining helps pathologists distinguish between osteoblastoma and osteosarcoma.

How is osteoblastoma treated?

Treatment for osteoblastoma usually means surgery to remove the tumor. The only exception is if the tumor is located in a tricky place on your spine that’s too risky to operate on. In this case, your orthopaedic surgeon will use other methods to try to destroy the tumor and stop it from growing.

Procedures to treat osteoblastoma may include:

• Curettage and bone grafting. Curettage means scraping out the abnormal tissue. After scraping it out, your surgeon may fill in the hole with a bone graft from your own body or a donor bone.
• En bloc resection. For a large or aggressive tumor, or one that’s come back after being removed, your surgeon might choose to remove the whole section of bone containing the tumor.
• Ablation therapy. If your surgeon can’t safely remove the tumor, they may attempt to destroy it with freezing temperatures (cryoablation) or by burning it out (radiofrequency ablation).

What can I expect if I have osteoblastoma?

Osteoblastoma usually has a good outlook. Most people are cured after surgery to remove the tumor. Most bones will repair themselves from the damage. But sometimes, the tumors can grow back again. This is more common after curettage than after resection. It might be because some tumor cells were left behind. If your tumor comes back after curettage, your surgeon might do a resection next time.