Bone cyst

Simple bone cysts are fluid-filled cavities in the bone. They occur most often in children and in the long bones of the arms or legs. The cause isn't known. But they're not related to cancer. A bone cyst may weaken the affected bone, increasing the risk of fracture.

Bone cysts usually don't cause symptoms. They're often discovered only after a fracture occurs in the affected bone. They may also be detected incidentally on an X-ray done for some other reason.

Treatment is directed at preventing recurring fractures. Most bone cysts eventually heal without treatment. When treatment is needed, it may include:

• Corticosteroids injected into the cyst
• Surgical removal of the cyst