Bone cyst

A bone cyst is a fluid-filled cavity in the bone. It is benign (non-cancerous), but it weakens the bone and makes it more likely to fracture (break).

Bone cysts usually occur in children, and occasionally in adults. There is no known cause.

Simple bone cyst

The most common type of bone cyst is the simple (unicameral) bone cyst. This is filled with watery fluid and is usually found in the humerus (upper arm bone) or thigh bone of growing children or teenagers. Unicameral bone cysts are more common in boys than girls.

In older children and adults, unicameral bone cysts can also occur in flat bones, such as the pelvis, jaw, rib cage, skull, ankle or heel bone.

Aneurismal bone cyst

A relatively rare type of bone cyst is the aneurismal bone cyst. This affects about one person in a million.

The large majority (75%) of aneurismal bone cysts occur in 10 to 20-year-olds, and they are more common in females than males. They tend to appear in the spine and the long bones (arm or leg bones), and differ from the simple bone cysts because they are filled with blood.

Glossary

Benign

Benign refers to a condition that should not become life-threatening. In relation to tumours, benign means not cancerous

Spine

The spine supports the skeleton, and surrounds and protects the delicate spinal cord and nerves. It is made up of 33 bones called the vertebrae

Blood

Blood supplies oxygen to the body and removes carbon dioxide. It is pumped around the body by the heart