Orthopedic Surgery

Aneurysmal Bone Cysts

An aneurysmal bone cyst is a benign blood-filled cyst in the bone that tends to expand or grow. While it is a cyst (a sac) it does have a thin bony wall surrounding the growth, so it is sometimes called a bony tumor. Even though it is not cancerous, aneurysmal bone cysts grows aggressively, so they must be removed.

Aneurysmal bone cysts (ABCs) can occur in the vertebral column as well as the extremities, usually occurring in people age 20 or younger. It can also occur in the rib cage.

About half of patients with aneurysmal bone cysts of the spine are children; most discover the cyst in their teen years. While ABCs are the second-most common tumors in children, they are rare and account for only 1-6 percent of bony tumors.

Aneurysmal bone cysts occur slightly more frequently in females than in males and there is a 20 percent recurrence rate with treatment. However, recurrence of ABCs of the spine is rare.

Causes of aneurysmal bone cysts

The causes of aneurysmal bone cysts are not known. Three divergent theories are being investigated:

Symptoms of aneurysmal bone cysts

Diagnosing aneurysmal bone cysts

If an aneurysmal bone cyst is not treated it can disrupt growth plates in young patients, cause neurologic symptoms (depending on its location), and fractures.

At The Children’s Hospital of Philadelphia, clinical experts use a variety of diagnostic tests to diagnose aneurysmal bone cysts, including:

Preparing for surgery

A minority of aneurysmal bone cysts will resolve on their own, but most will need to be surgically removed.

Though surgery for aneurysmal bone cysts is highly effective, we understand that any surgery can be a stressful experience for children and families. At CHOP, we offer a wealth of resources about how to prepare your child for surgery and what to expect during surgery.

Additionally, we employ numerous best practices before, during and after surgery to decrease the risk of infection and increase positive outcomes. Safety in spine surgery is a top priority.

Treating aneurysmal bone cysts

Treatment for aneurysmal bone cysts typically involves a four-step surgical process that includes:

After surgery for aneurysmal bone cysts, your child should expect to stay overnight in the Hospital.

In certain conditions, it is recommended to watch the tumor — instead of surgically treating it — and let it resolve on its own. When the growth is in a hard-to-reach place, an intralesional injection is often the best treatment. Your child’s clinical team will recommend the best treatment for your child’s individual situation.

Follow-up care for aneurysmal bone cysts

At The Children's Hospital of Philadelphia, we offer ongoing support and services for patients and families at our Main Campus and throughout our CHOP Care Network. Our team is committed to partnering with parents and referring physicians to provide the most current, comprehensive and specialized care possible for your child.

Aneurysmal bone cysts tumors can recur in 20 percent of patients, so it is important for your child to continue to see a doctor after treatment.

Your child will see the orthopedic surgeon about one to two weeks after surgery, then again at three and six months post-surgery. Annual monitoring by trained clinicians is strongly encouraged to monitor for possible recurrence of the growth.

If continued care and monitoring is necessary, we will help transition your child's care to an adult orthopedic team.

Long-term outcomes

Treatment for aneurysmal bone cysts of the spine usually results in few complications and low recurrence in children.


Contact us

To make an appointment with the Division of Orthopedic Surgery at The Children's Hospital of Philadelphia, call 215-590-1527 or contact us online.

Reviewed by: Jason L. Katz, PA-C, MHS, ATC-R, and John P. Dormans, MD, FACS
Date: January 2013 

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CHOP's Division of Orthopedic Surgery works closely with the Cancer Center to diagnose and treat children with benign and malignant tumors. Learn more about the Cancer Center at CHOP