Aneurysmal bone cyst of the maxilla.

An aneurysmal bone cyst of the maxilla is a nonneoplastic, uncommon, solitary bone lesion recognized by distinct radiographic and histopathological characteristics. It is described as a localized and quickly expandable benign tumor, which can reach a considerable size. It is characterized by the replacement of bone by spongy fibro-osseous tissue and a locally destructive and multicystic lesion filled with blood.