A giant cranial aneurysmal bone cyst associated with fibrous dysplasia.

An aneurysmal bone cyst (ABC) is a rare, benign fibro-osseous lesion, considered a vascular phenomenon secondary to fibrous dysplasia or a giant-cell tumour, and occurs mainly in long bones and vertebrae. In this case report a 16-year-old male presented with massive epistaxis. He was admitted with a 3-year history of chronic rhinitis, headaches, right ocular pain and recurrent epistaxis. CT scans showed a predominantly cystic, expansive mass obstructing both nasal cavities, extending to all paranasal sinuses and both orbits, with evidence of anterior cranial fossa skull base destruction. The patient underwent a craniofacial resection of the tumour performed with an external approach and an immediate reconstruction of the dural defect. Histology confirmed the lesion was an ABC associated with fibrous dysplasia. The patient's recovery was complete. A large facial aneurysmal bone cyst can damage the facial skeleton and skull base, and requires excision by a combined external approach.