Aneurysmal bone cyst of the ethmoid bone.

A 90-year-old woman presented with headache and diplopia, and a mass in the nasal cavity and paranasal sinuses was found on CT scan. The patient underwent examination under anaesthesia showing a mass arising from the ethmoid, apparently from the nasal septum. Biopsies taken showed an aneurysmal bone cyst. The patient opted against surgery and has been managed conservatively. A second CT scan 4 years later showed significant increase in size.