Pediatric aneurysmal bone cysts (ABC)

What are pediatric aneurysmal bone cysts (ABC)?

A pediatric aneurysmal bone cyst is a benign (noncancerous) growth. ABC’s most often develop during the teens and early 20s. They can develop in any bone, but are most often found in the arms, legs, torso and spine. ABCs often grow quickly and require comprehensive treatment because they can cause the affected bone to expand and deform. These cysts are called “aneurysmal” because they expand inside the bone the same way an aneurysm balloons and expands from within an artery.

What are the types of pediatric aneurysmal bone cysts (ABC)?

There are two types of aneurysmal bone cysts:

1. Active - Where the cyst grows but is contained within the bone

2. Aggressive - Where the cyst grows and spreads outside of the bone, affecting connective tissue like tendon and ligaments.

What are the signs and symptoms of a pediatric aneurysmal bone cyst?

• Pain and swelling in or around the affected bone

• A lump or bump under the skin, on or near a bone

• Fractures which occasionally occur when the cyst creates enough pressure to crack the bone.

• Neurological symptoms such as weakness, tingling or numbness in the lower extremities if the cyst is in the spine.

How are pediatric aneurysmal bone cysts (ABC) diagnosed?

We may use the following tools to diagnose an aneurysmal bone cyst:

• X-rays to take pictures of the bones

• Computed tomography (CT) scan to take detailed images from several angles of bones, blood vessels and soft tissue, providing more information than a typical X-ray.

• Magnetic resonance imaging (MRI) to create detailed 3D images of the bones, muscles and organs.

• Biopsy where doctors take a small tissue sample and study it in a lab

What are the causes of pediatric aneurysmal bone cysts (ABC)?

Scientists are still working to find the exact cause of aneurysmal bone cysts. They may happen because of abnormalities in the blood vessels within the bones. Certain gene changes (genetic mutations) are also associated with ABCs.

How is are pediatric aneurysmal bone cysts (ABC) treated?

Our care team will create a custom treatment plan based on several factors including your child’s age and where the cyst is located.

Treatment options include:

• Curettage and bone grafting - Curettage is the most common way to treat an aneurysmal bone cyst. In this procedure, we use a tool called a curette to scrape the cyst out of the bone. Then, we fill the remaining space inside the bone with bone tissue from a donor, tissue from somewhere elsewhere in the child’s body or with a bone-like material. We may also perform a procedure called “extended curettage” where we remove extra cells surrounding the cyst to help keep the cyst from growing back.

• Marginal or wide excision - If an ABC is located on a bone a child can live without (such as a rib), we may perform a marginal excision. This procedure removes part of the affected bone. A wide excision removes some of the bone and surrounding tissue.