A bone cyst is a fluid-filled hole that develops inside a bone. They can occur at any age, butmost oftenaffect children and young adults.

Bone cysts don't usually cause any symptoms. They are not cancerous and they do not usually pose a serious threat to health.

However, large cysts can cause a bone to weaken, making it morelikely tofracture (break).This cancause problems such as pain, swelling,or not being ableto move or put weight on a body part.

Unicameral bone cysts

Unicameral bone cysts are the most common type of bone cyst. They can develop anywhere in the body, although most cases involve either the upper arm orthigh.

The condition tends to affect younger children between 5 and 15 years of age. Boys are abouttwice as likely to have unicameral bone cysts as girls.

The exact cause ofunicameral bone cysts is unknown, but a leading theory suggests they may occur due to problems with the drainage of interstitial fluid from growing sections of bone.

Aneurysmal bone cysts

Aneurysmal bone cysts are a rarer type of bone cyst where the bone contains a pocket of blood.They can also develop anywhere in the body, but most often affect the legs, upper arms, pelvis or spine.

Most cases affectchildren and young peopleaged between 10and 20. It's thought thataneurysmal bone cysts may beslightly more common in females than males.

The exact cause of aneurysmal bone cysts is not clear. They may occur because of an abnormality in the blood vessels inside affected bones, which develop as a result of a previous injury or anon-cancerous growth inside the bone.

Diagnosing bone cysts

Bone cysts can usually be diagnosed by looking at an X-ray of the affected bone. This will highlight any hollow cavities or fractures in the bone.

In many cases, a bone cyst will only be discovered by chance whenX-raysare used to diagnose an unrelated condition, orafteran affected bone has fractured.

A computerised tomography (CT) scan , a magnetic resonance imaging (MRI) scan , and/or a biopsy (where a sample of fluid is removed from the bone with a needle and tested) may sometimes be carried out to confirm the diagnosis.

How bone cysts are treated

Many bone cysts will eventually heal without the need for treatment and won't cause long-term problems particularlyunicameral bone cysts in children, which will usually disappear by the time they stop growing.

If a bone cyst does not get better, or if treatment is recommended to help reduce the risk of a fracture, several options may be available.

For example, steroid medicationcan be injected into the bone to encourage the cyst to heal. If this doesn't help, surgery may be needed to drain the fluid and fill the hole with chips of bone.

There is a significant chance of the cyst recurring after treatment, so you may need to have regular X-rays for a few yearsafterwards to look for signs of the condition returning.


Content supplied by the NHS Website

Medically Reviewed by a doctor on 22 Aug 2016