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.