Pneumatocele of the orbit

Purpose: To describe an uncommon sinus condition that can cause proptosis. Methods: Intermittent unilateral proptosis and diplopia developed in a 29-y ear-old man. Computed tomography showed an enlarged frontal sinus with eros ion of the floor of the sinus and air in the orbit. Results: Endoscopic ethmoidectomy and frontal sinusotomy corrected an outle t check valve of the nasal frontal duct and eliminated the proptosis. Conclusion: Pneumatocele of the orbit is an uncommon cause of proptosis and diplopia and can be corrected with endoscopic sinus surgery.