What is an aneurysmal bone cyst?
An aneurysmal bone cyst is a blood-filled fibrous tumor-like cyst that expands the bone, giving it a “blow-out” appearance. It typically occurs in the second decade of life and can emerge in virtually any bone in the arms, legs, trunk or skull. The vertebrae and knee are the most common sites of occurrence. An aneurysmal bone cyst is a benign bone tumor, meaning that it does not metastasize (spread) to other regions of the body. It can however be quite destructive locally and has a high propensity for recurrence. When it occurs in bones of a limb, it typically involves any of the following areas of the bone: • Metaphysis – the transitional zone where the shaft of the bone joins the end of the bone • Diaphysis (shaft) – bone near the growth plate (the area of the bone in which growth occurs) When it occurs in the spine, the cyst can grow to involve the entire vertebral body where it arose or it can involve the adjacent vertebrae. Generally, those cysts considered “active” could deform t