Boots WebMD Partners in Health
Return To Boots

Bone cysts

What are bone cysts?

A bone cyst is a fluid-filled lesion that develops inside a bone. They are not cancerous and usually only affect children and young adults.

Someone with bone cysts won't usually notice any symptoms, but if a cyst gets bigger, it can weaken a bone, making a fracture more likely.

Unicameral bone cysts are the most common type of bone cyst. These affect boys more than girls, are most common between 5-15 years old, and mostly occur in the upper arms and thighs.

A rarer type are aneurysmal bone cysts, where there's a pocket of blood inside the bone. These cysts may cause symptoms including pain, lumps, swelling or reduced movement.

It isn't clear what causes bone cysts to develop. Unicameral bone cysts may be caused by fluid drainage problems in growing bones. Aneurysmal bone cysts may be due to problems with blood vessels in a bone from a previous injury or a non-cancerous growth. Another theory is that genetic abnormalities cause the cysts to form.

Bone cysts are usually detected during tests such as X-rays, CT scans or MRI scans for other conditions.

Bone cysts often get better on their own as a child gets older without needing any treatment. This is probably why bone cysts are rare in adults.

If treatment is needed to help prevent bone fractures, steroid injections may be given into the bone, or an operation carried out to drain the fluid and fill the hole with bone chips.

Doctors may be concerned if a cyst is affecting normal bone growth, or if there are other symptoms, which in rare cases may suggest bone cancer.

Doctors will also be concerned if an aneurysmal bone cyst affects the spine, where it may disrupt the body's nervous system, causing muscle weakness, numbness or headaches.

WebMD Medical Reference

Medically Reviewed by Dr Rob Hicks on May 17, 2017

Stay informed

Sign up for BootsWebMD's free newsletters.
Sign Up Now!

Popular slideshows & tools on BootsWebMD

woman_holding_head_in_pain
How to help headache pain
rash on skin
Top eczema triggers to avoid
boost your metabolism
Foods to lower LDL (bad) cholesterol
period_questions_answered
Tips to support digestive health
woman looking at pregnancy test
Is your body ready for pregnancy?
sick child
Dos and don'ts for childhood eczema
girl_sneezing_into_tissue
Treating your child's cold or fever
bucket with cleaning supplies in it
Cleaning and organising tips
adult man contemplating
When illness makes it hard to eat
woman holding stomach
Understand this common condition
cold sore
What you need to know