Aneurysmal Bone Cysts (ABCs) in Children

What Causes Aneurysmal Bone Cysts?

The exact cause of ABCs is not known, but they are not thought to be passed down in families. Some studies have shown that a small number of ABCs are linked to a change in a gene.

ABCs can form on their own (spontaneously), or they may develop as a reaction to other bone growths, such as chondroblastomas, giant cell tumors, or osteoblastomas.

What Are the Signs & Symptoms of Aneurysmal Bone Cysts?

The presence of an aneurysmal bone cyst destroys a bone by weakening it.

Symptoms can include:

• Pain in the affected bone
• Swelling around the affected bone
• Stiffness of the affected bone
• Deformity in the area of the growth
• Feeling of warmth over the affected area
• Decreased range of motion, weakness or stiffness
• Fracture of the bone due to weakening
• Pressure on adjacent nerves or rarely the spinal cord (in cases of spinal ABCs)

If an aneurysmal bone cyst is not treated, it can cause the bone to become fragile and thin, which may result in pain, fractures, disrupted growth and the on-set of neurological symptoms.

How Are Aneurysmal Bone Cysts Diagnosed?

To determine the best course of treatment for your child, Lurie Children’s uses the following diagnostic tests to diagnose the specific type of cyst your child has, as well as its location and size:

• Magnetic resonance imaging (MRI)
• Computed tomography (CT) scan
• X-rays
• Angiography, a test that uses x-rays and a special dye to see inside the arteries
• Needle biopsy, a test where a doctor uses a small needle to take a tissue sample from the abnormal area for testing. This is sometimes performed when there is concern for a secondary ABC.

(ABOVE) Percutaneous treatment of a fibula ABC with sclerosis and bone grafting; 9 month radiograph (RIGHT) Shows no evidence of residual cyst with bone remodeling.  

How Are Aneurysmal Bone Cysts Treated?

The treatment for ABCs depends on several factors, such as where the cyst is located and how close it is to important structures. In the past, surgery was the main treatment for ABCs. Now, there are newer, minimally invasive options done by interventional and neurointerventional radiologists. These procedures allow for quicker recovery times and similar rates of recurrence.

Sclerograft Procedure (Sclerosing and Grafting)

This technique is often used for ABCs, similar to how we treat simple bone cysts. While your child is asleep, a doctor uses needles to break up the cyst and drain the fluid. A chemical called a sclerosant is then injected into the cyst to destroy the abnormal tissue. Sometimes, another procedure called cryoablation is also used to help prevent the cyst from coming back.

After that, a special bone graft is injected into the cyst. This graft helps the bone heal and become stronger. The graft is temporary and usually dissolves within a year as new bone forms.

Embolization

Embolization is mainly used for ABCs in the spine when other treatments are difficult. A doctor uses small tubes called catheters to reach the blood vessels feeding the cyst. Then, tiny particles are injected to block these vessels, which helps the bone heal and fill in the cyst.

Your care team will help you choose the best treatment for your child’s case.

ABCs are usually treated with sclerotherapy. This method often requires multiple procedures under general anesthesia. It can also take months for the cyst to heal enough to see changes on regular X-rays, so MRIs or CT scans are often needed to track progress.

At Lurie Children’s, we use a different approach. By combining mechanical disruption of the cyst with regenerative bone grafting and cryoablation, we aim to reduce the number of procedures and limit the number of times your child needs anesthesia. The bone graft helps speed up healing, so we can monitor progress with simple X-rays, and your child can return to normal activities sooner.

ABCs are similar to simple bone cysts (UBCs), but they are more aggressive and harder to treat. They are made up of multiple chambers (multiloculated), which makes them more likely to come back. Unlike UBCs, which can sometimes go away on their own, ABCs usually cause pain or limit movement and often need treatment to prevent growth or fractures.

Treating ABCs takes a team approach. At Lurie Children’s, we work closely with interventional radiologists, pediatric orthopedic surgeons, and pediatric neurosurgeons to give your child the best care possible. Our goal is to help your child heal and get back to being a kid again.

After treatment, your child will have regular checkups every few months for three years to make sure the bone is healing well and there is no evidence of recurrence.