The gross appearance of an aneurysmal bone cyst (ABC) is shown here. The radiographic appearance of an ABC is typically that of ballooning, or aneurysmal dilation, of the affected bone--usually the metaphysis of a long bone or dorsal vertebral body. Grossly, there are fleshy aggregates of tumor surrounding cystic spaces filled with blood. The breakdown of the blood into hemosiderin has led to brownish staining of some of the cysts seen here.

---