Bone cyst
Overview
Bone cysts are fluid-filled holes that form in bones. They mainly affect children and teenagers. They're not usually serious, but they sometimes need to be treated with surgery.
Symptoms
Symptoms of a bone cyst can include: pain, swelling or a lump, usually in your arm, leg or spinenumbness or tingling, if the cyst affects your spinea break (fracture), sometimes from a relatively minor injury Bone cysts do not always cause symptoms. Sometimes they're found after they cause a fracture, or if you have an X-ray for another reason.
Causes
The exact cause of bone cysts is unknown. They're not cancer and do not spread to other parts of the body. The main types of cyst are thought to have different causes: unicameral bone cysts – fluid-filled holes that may form if fluid does not drain properly from a bone as it's growinganeurysmal bone cysts – blood-filled holes that may be caused by a problem with the blood vessels in a bone (possibly due to an injury or a non-cancerous growth)
Treatment
If you have treatment for a bone cyst it normally takes at least a few months for the bone to heal. You may need to avoid activities or sports that could damage the bone until it has healed. You'll have regular X-rays for a few years to check it's getting better. It's quite common for bone cysts to come back, especially in the first couple of years after treatment.