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Osteofibrous Dysplasia (OFD)

Osteofibrous dysplasia makes up less than 1% of all tumors that originate in bone. It usually develops in people younger than 20 years of age, and stabilizes when the bones are no longer growing.

Almost all OFD tumors occur in the long middle part of the tibia, with a few, rare reports of occurrences in the fibula (the smaller bone in the calf), as well as the long bones in the arm (humerus, radius, and ulna). OFD grows within the hard, cortical bone that makes up the outer portion of these bones.

Adamantinoma

Like OFD, adamantinoma is very rare. Fewer than 1% of all cancerous tumors that begin in the bone are adamantinomas.

These slow-growing tumors most often occur in the middle part of the tibia, and in many cases, the fibula bone is also affected. Although uncommon, adamantinomas have also been found in the bones of the arm, rib, pelvis, foot, and spine. Adamantinoma tumors are more aggressive, and can destroy the outer cortex or spread into the central canal of the bone. In many cases, adamantinomas affect the muscles and other soft tissues surrounding the bone, as well.

Unlike OFD, in about 15% of cases, adamantinomas metastasize (spread) to other areas of the body — most often the lungs, lymph nodes, as well as other bones. There have been reports of metastasis occurring years after the first diagnosis and subsequent treatment.

Although adamantinomas can develop in anyone at any age, teenage boys and young men are most often affected.

Both OFD and adamantinomas develop in hard, cortical bone. An adamantinoma may aggressively grow into the center canal of the bone, or out into the soft tissues that surround the bone.

Medical History and Physical Examination

Before a physical examination, your doctor will talk with you about your general health and your symptoms in order to get a good history of the problem. During the physical examination, your doctor will look for tenderness over the bone, swelling, or a mass in the area of your symptoms.

Tests

The signs and symptoms of OFD and adamantinoma are similar to many other types of bone tumor. Your doctor may use several tests to distinguish between different tumors and make an accurate diagnosis.

• X-rays. These tests provide clear pictures of dense structures like bone, and are very helpful in diagnosing bone tumors. Different types of tumors have different characteristics on x-ray. For example, an OFD has very obvious borders and can look like one big tumor or several smaller areas of tumor. An adamantinoma has a "soap bubble" appearance in x-rays.

(Left) This x-ray of the tibia taken from the side shows several smaller areas of tumor, which is a sign of OFD. (Right) The typical "soap bubble" appearance of an adamantinoma is obvious in this tibia x-ray.

• Other imaging scans. More imaging studies may be needed to further evaluate these tumors. Your doctor may also request computerized tomography (CT) scans, magnetic resonance imaging (MRI) scans, or bone scans to help further define the tumor. These scans can provide more detail, especially of soft tissues. They can also provide cross-sectional images.
  
  A CT scan or MRI scan will show your doctor more precisely where the tumor is located and what its specific characteristics are. For example, in a CT scan, your doctor can see if the adamantinoma tumor has broken through an area of the bone.

In this cross-section CT scan of the tibia, an OFD shows up clearly as bright white against the darker color of the bone.

• Biopsy. A biopsy may be necessary to confirm whether the tumor is OFD, an adamantinoma, or an OFD-like adamantinoma. In a biopsy, a tissue sample of the tumor is taken and examined under a microscope. Your doctor may give you a local anesthetic to numb the area and take a sample using a needle. Biopsies can also be performed as a small operation.

  If your doctor diagnoses the tumor as adamantinoma, you may require some additional testing to determine whether the disease has spread to other areas, such as a CT scan of your chest or a bone scan.

Nonsurgical Treatment

Because OFD is not cancerous and usually will not grow after the patient reaches skeletal maturity, treatment typically involves observation. Your doctor will monitor the tumor with regular x-rays taken every few months. An OFD-like adamantinoma is treated in the same manner.

If the tumor is weakening the bone enough to cause it to bow or change shape, your doctor may recommend wearing a brace. This may also prevent the tumor from causing the bone to break.

Surgical Treatment

In cases in which OFD or an OFD-like adamantinoma causes serious bone deformity or fractures, surgery is often recommended to remove the tumor and stabilize the bone.

Adamantinomas always require surgery. They do not respond to other cancer treatments, such as chemotherapy and radiation.

• Limb salvage surgery. In this procedure, your doctor removes the section of bone where the tumor is located, as well as some healthy tissue surrounding it. The hole is filled with a bone graft — this is bone taken from a cadaver (allograft) or from another bone in your body (autograft) — to stabilize the bone and promote healing with new bone growth. Sometimes, the hole requires reconstruction with a metallic implant (prosthesis) to stabilize the bone.

(Left) This x-ray taken from the side shows an adamantinoma in the tibia. (Right) The tumor and surrounding bone have been removed and replaced with an autograft.

• Amputation. If the adamantinoma cannot be completely removed with limb salvage surgery, or nerves and blood vessels are involved, all or part of the limb may need to be removed. Your surgeon will talk with you about the benefits of limb salvage versus amputation. 
• Recovery. After surgery, your doctor may take more x-rays and other imaging studies to confirm that the tumor has been completely removed.  
  
  How long it will take to return to daily activities will vary, depending on how large the tumor was and where it was located. Your doctor will provide you with specific instructions to guide your rehabilitation.
  
  Regular doctor visits and tests every few months may be needed.