What Is a Bone Island?

A bone island is a benign growth of bone or cartilage inside a bone, usually within the marrow. It shows up on a medical imaging study, such as an X-ray, as a point of increased density and is believed to be caused by overproduction of bone or cartilage cells. Terms such as enostosis and enchondroma may be used to refer to a bone island. Often, these growths are diagnosed while a patient is being evaluated for another condition.

Bone islands can be congenital or developmental. In many people, they cause no ill effects and the patient may be unaware of the bone island or bone islands in the body. Sometimes, however, they can cause pain, especially after exercise. People who experience bone pain usually seek medical treatment for it and the bone island will be diagnosed in the process of evaluating the patient. An orthopedic doctor is usually involved in the diagnosis and treatment of a patient with a bone condition and an oncologist may be involved as well.

While bone islands are benign, other conditions that are not benign can look like a bone island at first glance. When such growths are identified, a doctor will usually recommend additional diagnostic testing to find out exactly what is going on. The doctor does not want to miss something like a malignant tumor. Patients will also be asked about any symptoms they may have experienced and how long they have noticed those symptoms, as this information can be key to determining whether an irregularity in a medical imaging study is a bone island or something else.

Common locations for bone islands include the hip, the fingers, and the thigh. In addition to growing in people, these growths can also be found in animals, especially dogs and horses. A review of the images can often reveal whether or not the growth is bone or cartilage, in addition to showing the precise location and extent of the growth. Usually, images are kept on file so they can be compared with new images on periodic checkups to determine whether or not the growth is changing.

Sometimes, these growths can become cancerous. People with certain genetic conditions are at risk of cancers of the bone, and a bone island can develop into a malignant tumor in these patients. Someone who is at risk may be monitored for any signs that the growth is behaving abnormally. Options for treatment can include surgery to remove the growth if it is causing pain or it becomes malignant.

Bone islands can appear on any bone and any spot in the skeleton. They can grow in certain locations more frequently than others. For instance, the pelvis, ribs, and femur are the most common locations for bone islands to form.

Bone islands are typically discovered when a patient is at the office or hospital to be treated for something else. It is possible to experience symptoms of a bone island (or confuse them for other bone-related problems). Below are symptoms of bone islands:

Since the symptoms of a bone island are so non-specific, patients often ignore them their entire lives. However, they can get worse over time.

Bone islands can appear on any part of the skeleton and are common in people. Luckily, they are usually harmless. Plus, it is unlikely that one or more bone islands a patient has will spread to other parts of their body but this isn’t always the case.

Although it’s rare, some bone islands do require treatment. While bone islands can be largely ignored, they can be malignant or cancerous. This is why it is crucial to visit a doctor whenever the symptoms manifest.

If they metastasize, the bone islands may spread to other body parts. This might go on for years without the patient noticing because the symptoms are generally rare and minimal. It’s rare for bone islands to cause pain; when they do, the pain is usually minimal.

If a patient is diagnosed with a malignant bone island, the doctor will likely run more scans and suggest treatment to remove the growth. This may also be true if the bone island is especially painful.

No, bone islands do not go away on their own. For most people, this isn’t going to be a concern. Most bone islands pose no threat to the patient but if they’re malignant, the patient will need treatment. This often means surgery and will likely be scheduled as soon as bone island growth is verified as malignant. Studies show that bone islands grow at different rates but expand over time.

It’s very rare for bone islands to be cancerous and even rarer for one that’s initially benign to become cancerous. One might go their whole life without knowing they have one or more bone islands.

The only way to know if a mass of any kind, whether on the skin or the bone, is cancerous is to see a trained medical professional and have one more scan completed on that part of the body. The doctor will likely perform a biopsy to test the mass to see if it is malignant.

It’s impossible to prevent bone islands from forming since doctors aren’t sure what causes them. However, since it’s far more likely that they’re going to be harmless, it’s not something that doctors usually worry about or advise their patients to prevent.

For those with a history of cancer, seeing a doctor regularly will ensure that no malignant bone islands are developing and, if one is present, that it is caught right away at the earliest opportunity.

These two distinct types of bone growth have many similarities and some important differences. 

Doctors are unsure what exactly causes bone islands whereas bone spurs result from osteoarthritis damage and commonly form in the hands, neck, knees, hips, heels, and the spine. Many symptoms common to bone islands are also present for someone suffering from bone spurs, including pain, swelling, and stiffness. In the spine, the pinching and compression of nerves due to the projecting bone spurs can cause chronic pain.