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Pediatric Aneurysmal Bone Cyst (ABC)

What is Pediatric Aneurysmal Bone Cyst (ABC)?

An aneurysmal bone cyst (ABC) is a benign (noncancerous) blood-filled, fibrous growth.Typically occurring during the teenage years, aneurysmal bone cysts can grow on almost any bone, including the arms, legs, skull, spine and torso. The cyst will cause the bone to expand and deform. They can be removed with surgery, but may grow back.

What are the different types of Pediatric Aneurysmal Bone Cyst (ABC)?

There are two types of aneurysmal bone cysts:


Active – continues to grow, but is contained within the bone


Aggressive – continues to grow and spreads outside the bone to the soft, connective tissue like ligaments or tendons

What are the signs and symptoms of Pediatric Aneurysmal Bone Cyst (ABC)?

Symptoms of aneurysmal bone cysts range from mild to severe and can include:

  • Fractures caused by pressure due to the cyst
  • Neurological problems (if the cyst is in the spine)
  • Pain
  • Swelling

A pediatric aneurysmal bone cyst (ABC) is a benign (noncancerous) blood-filled, fibrous cyst. Learn more about the causes and symptoms.

What are the causes of Pediatric Aneurysmal Bone Cyst (ABC)?

The exact cause of aneurysmal bone cysts is unknown. Experts believe the cysts may grow due to a blood vessel abnormality in the bones, or because of a pre-existing condition like fibrous dysplasia (scar-like tissue forms instead of bone) or osteosarcoma (cancer that begins in bone cells).