Bone cysts often have no symptoms. They may not be discovered until you fracture (break) the bone, or until you have an X-ray for another reason.

Unicameral bone cysts

Most unicameral bone cysts do not cause any symptoms unless the affected bone becomes severely weakened, causing it to fracture.

Signs and symptoms of a fracture can include:

• pain and swelling
• bruising or discoloured skin around the bone or joint
• the limb or affected body part being bent at an unusual angle
• inability to move or put weight on the injured limb or body part

In most cases, the bones of the upper arms or legs are affected.

Occasionally, unicameral bone cysts may cause pain without any obvious signs of a fracture, and they may disrupt the growth of the affected bone.

Aneurysmal bone cysts

Signs and symptoms of an aneurysmal bone cyst can include:

• persistent pain and swelling
• a noticeable lump or deformity in the bone
• decreased range of movement, weakness or stiffness in the affected body part
• the skin in the affected area being warm to the touch

Most aneurysmal bone cysts affect bones in the legs, upper arms, pelvis or spine.

If an aneurysmal bone cyst develops inside the spine, it can disrupt the normal working of the nervous system and cause additional symptoms, such as:

• muscle weakness
• a shooting pain in the arms or legs (sciatica)
• numbness or a tingling sensation in the arms and legs
• problems with bladder or bowel control

Although it happens less often than in unicameral bone cysts, aneurysmal bone cysts can also sometimes cause fractures in affected bones.

When to seek medical advice

You should contact your GP if you or your child experiences persistent bone pain or any of the signs of a problems described above.

If you think that you or your child has a fracture, go to your nearest accident and emergency (A&E) department. Dial 999 for an ambulance if the injury is severe.