[Removal of a giant ethmoidal sinus osteoma with orbital extension].

Osteomas are slow growing bony tumors of the nasal sinuses. Ethmoid osteomas with orbital extension are unusual. Any surgical approach has to take into account protection of the vital structures, particularly the optic nerve and internal rectus muscle, skull base. A 65-year-old man, without past medical history, was referred to our hospital with a 1-month history of double vision and persisting pain around the left eye. Three-dimensional computed tomography (CT) revealed a large calcified dense mass measuring 32 mm × 25 mm × 25 mm in the left ethmoidal sinus with orbital extension. An endoscopic endonasal approach combined with inner canthus way was planned. Most of the tumor was removed from nasal cavity, the rest part of the tumor was taken out of the inner canthus incision. The medial wall of the orbital cavity was repaired with titanium mesh. No cerebrospinal fluid (CSF) leakage was observed during the procedure. The patient recovered rapidly and had no visual impairment and occular motility disorders after operation. The double vision was alleviated and disappeared after one months. Treatment of large ethmoid osteomas requires a combined approach to prevent injury to the orbital content. The cooperation of both otolaryngologists and ophthalmologists is necessary to achieve risk-free surgery.