Solid aneurysmal bone cyst of the mandible.

Aneurysmal bone cyst is a rare, rapidly expanding, locally destructive, and often misdiagnosed lesion. It accounts for about 1-2% of primary biopsied bone tumours. About 60-70 cases have been reported in the jaws; particularly the molar regions. Eighty percent of patients are under 20 years of age. Aneurysmal bone cyst exists as a primary or secondary lesion. It may be conventional (95%) or solid (5%). The solid variant is more difficult to recognize. The practical importance of aneurysmal bone cyst lies in the fact that it must be differentiated from malignant tumours: mainly with giant cell tumours and teleangiectatic osteosarcoma.