Ethmoidal air cell schwannoma presented as a fronto-ethmoidal mucocele.

AIM: To report a rare case of a fronto-ethmoidal mucocele secondary to an ethmoidal schwannoma. To our knowledge this is the first reported case of an ethmoidal schwannoma, a tumour of the peripheral nerve sheath originating from an area not believed to contain peripheral nerves that has presented as a fronto-ethmoidal mucocele. CASE REPORT: Our patient is a 23-year-old male presented with a one-year history of progressive proptosis and vertical diplopia with restriction of upgaze. Orbital imaging demonstrated a mass in the right medial ethmoidal air cells extending to the frontal sinus and orbit, consistent with a mucocele. Patient underwent endonasal decompression of the right fronto-ethmoidal mucocele. Histology confirmed a schwannoma and repeat imaging post-operatively revealed residual mass originating from the ethmoidal air cells. A right upper eyelid skin crease approach anterior orbitotomy was performed to successfully excise the mass via the lamina papyracea. Post-operatively the patient's proptosis and diplopia resolved, with a full range of ocular movements. Post-operative imagining at 3 months did not show any residual tumour. COMMENT: Mucocele formation may be secondary to an underlying schwannoma obstructing the fronto-ethmoidal foramen. In such cases we recommend an open-sky technique for full visualisation and improved chance of total removal.