Aneurysmal Bone Cyst

Epidemiology

The etiology of aneurysmal bone cysts (ABCs) is controversial. Lichtenstein suggests that ABCs result from a persistent local alteration in hemodynamics leading to increased pressure and subsequent transformation of the area into a dilated and engorged vascular bed. Some authors feel that ABCs represent an unorganized or canalized portion of a hematoma or false aneurysm. Still others suggest that ABCs are secondary lesions that result from a vascular response initiated by a separate primary bone lesion. These masses are more common in females and individuals under the age of 20. They are more likely to involve the mandible as opposed to the maxilla or zygoma. These lesions are often associated with a prior history of trauma to the site of origin.

Clinical Features

ABCs usually present with a rapidly increasing swelling in the absence of pain or paresthesias that results in facial deformity and malocclusion. There may be spontaneous bleeding around the teeth or from mucosal trauma.

Pathology

Grossly, the lesions are characterized by a spongy appearance with blood-filled spaces. Histologically, these are epithelial-lined lesions consisting of numerous cavernous blood-filled cavities located in a honeycombed meshwork of connective tissue. These lesions also contain multinucleated giant cells, areas of osteoid, inflammatory cells, and hemosiderin.