Osteoblastoma

Osteoblastoma is a rare, non-cancerous, aggressive bone tumor. It tends to form in any of the bones in the hands and feet, but it can also occur in the spine where it can lead to scoliosis and neurological symptoms. It accounts for only one percent of all primary bone tumors.

Types & Stages

Osteoblastoma is generally divided into two types:

• Conventional osteoblastoma. Also called ordinary osteoblastomas, they’re a rare, slow-growing tumor that is routinely larger than 2 cm. They’re formed by osteoblasts that deposit bone trabeculae, which are thin, beam-like structures that form the spongy, porous interior of many bones. 
   
• Epithelioid or aggressive osteoblastoma. It’s a rare, locally aggressive variant of a benign (noncancerous) bone tumor characterized by the presence of enlarged, epithelioid osteoblast cells whose primary function is to form bone.

Osteoblastoma may also occur in conjunction with an aneurysmal bone cyst (ABC), another benign tumor. It is also closely related to osteoid osteoma, a more common benign bone tumor that tends to be smaller. 

Signs & Symptoms

The most common symptoms of osteoblastoma include: 

• pain, usually increasing in severity with time
• swelling
• atrophy of affected area
• painful scoliosis, a sideways curve of the spine
• muscle spasms
• limited range of motion

Diagnosis

Tests and procedures to diagnose an osteoblastoma may include:

• Imaging tests. These may include:
   
  • 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 (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. 
     
  • 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. 
     
  • Bone scans. A whole-body bone scan is a nuclear medicine test to check your bones for issues or changes. You receive an injection of a substance called a radiotracer. The radiotracer collects in areas of irregular activity and highlights these areas on an imaging scan. 
     
• Bone biopsy. During this test, your doctor takes a small amount of bone tissue from an area affected by the disease to examine under a microscope.

Treatment

Treatment for osteoblastoma usually involves an operation to remove the tumor performed by an orthopedic surgeon and include:

• Curettage/bone grafting. Curettage describes a surgical scraping of the cyst with a special instrument called a curette that has a scoop, loop, or ring at its tip. This procedure may be opted for if the tumor cannot be removed by excision. Sometimes, 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, the operation will likely involve en bloc resection, which is the surgical removal of bone containing the tumor. Internal fixation, with pins, may be required to restore the structural integrity of the bone.

Causes & Risk Factors

The exact cause of osteoblastoma is unknown. Risks include:

• Age. It typically occurs in the second decade of life, but patients range in age from about 5 to 45. 
• Gender. It affects males more than females at a ratio of 3 to 1.

Screening

There is no routine screening test for osteoblastoma.