[Benign fibro-osseous lesions of the craniofacial complex with aneurysmal bone cyst formation]

Aneurysmal bone cyst are controversial osteolytic benign expansive lesions which occur more frequently in the metaphysis of long bones and spine. They are classified as primary or secondary lesions depending on the presence or absence of an associated bone pathology. The engraftment of aneurysmal bone cyst onto benign fibro-osseous lesions is established. However, in the craniofacial complex this combined lesion is rare.The authors present two histologically proven uncommon cases of benign fibro-osseous lesions (fibrous dysplasia and juvenile psammomatoid ossifying fibroma) with aneurysmal bone cyst formation, emphasizing the imaging characteristics of this hybrid entities.