Aneurysmal Bone Cysts (ABCs)

What Are Aneurysmal Bone Cysts?

An aneurysmal bone cyst (ABC) is a benign but highly destructive bone tumor typically found around the knee, pelvis or spine. ABC’s are predominantly seen in children and adolescents, with 80% occurring in patients under 20 years old.

What Causes Aneurysmal Bone Cysts?

The cause of ABCs is currently unknown, but they are not believed to be hereditary. However, some research does suggest that ABCs have been linked to a mutation of a gene.

Aneurysmal bone cysts may occur spontaneously, or they may be a secondary reaction to other lesions of the bones, such as giant cell tumors, osteoblastomas and hemangiomas.

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 ABC’s)

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:

• X-rays
• Magnetic resonance imaging (MRI)
• Computed tomography (CT) scan
• Angiography, a test that uses x-rays and a special dye to see inside the arteries
• Needle biopsy, procedure where a doctor places a small needle through the skin and into the lesion to withdraw a small sample of the abnormal tissue

How Are Aneurysmal Bone Cysts Treated?

Treatment for ABCs has evolved in recent years. While surgery was previously the primary treatment for ABCs, there are now minimally-invasive approaches performed by interventional and neurointerventional radiologists that allow for faster recovery time and reduced risk of occurrence. Learn more about our Interventional Radiology Program and Neurointerventional Radiology Program.

Your care team will guide you through the treatment options best suited for your child’s case.