Background: Mucoceles are epithelium-lined cavities in the paranasal sinuses filled with mucus. They develop because of scarring and obstruction of the sinus ostium, whether from chronic sinusitis, trauma, or surgery. They commonly erode the bony sinus wall and can have serious complications of brain and orbital invasion, with potential for abscess and rupture.
Case report: A 39-year-old woman had diplopia in left gaze and a hard nodule above the right eye for 1 year. She recently noted a bulging right eye, nasal congestion, and occasional headaches. She was 9 years post-sinus surgery. All aspects of the afferent optic nerve function were intact. Right-sided proptosis was evident as was a right adduction and supraduction deficit, prompting immediate imaging, both with a computed tomography scan and magnetic resonance imaging of the orbits. These results showed a large right ethmoid sinus mucocele, with bony erosion and orbital invasion, prompting an immediate surgical referral.
Conclusion: Mucoceles may arise from any of the paranasal sinuses and, because of the close proximity of these spaces to the orbit, may initially manifest with visual and ocular signs and symptoms. Therefore, eye care providers need to be aware of this entity and the need for immediate referral or workup if a mucocele is suspected.