Diplopia Revealing a Frontal Mucocele: A Case Report

Abstract

Mucoceles are benign, expansile pseudocystic lesions of the paranasal sinuses caused by sinus ostial obstruction and chronic inflammation. They are rare pathologies, mainly affecting adults, and are most commonly located in the fronto-ethmoidal sinus system. Mucoceles are characterized by clinical polymorphism, insidious onset, and slow progression, which explains why they are often discovered at the stage of ophthalmological complications. Diagnosis is clinical and radiological, and management is essentially surgical. We report the case of a 65-year-old diabetic male with no previous ophthalmological history who presented with permanent diplopia lasting two weeks. Clinical examination revealed constant vertical binocular diplopia with limited mobility of the left eye, associated with homolateral non-pulsatile ptosis and exophthalmos, without inflammatory signs. The left eye was deviated downward and outward. The remainder of the ophthalmological examination was unremarkable. Diagnosis was established by orbital magnetic resonance imaging (MRI), which showed a left frontal sinus mucocele with orbital extension The patient underwent endoscopic marsupialization, with a favorable postoperative outcome outcome : complete visual recovery; exophthalmos and diplopia resolved, and oculopalpebral motility normalized by day 15. This case highlights that persistent diplopia may be the presenting sign of a frontal sinus mucocele, underscoring the importance of early imaging for timely diagnosis and management. In conclusion, paranasal sinus mucoceles are rare benign lesions that most often present with ophthalmological symptoms. Their severity lies in the risk of compression of vital adjacent structures. Diagnosis is based on clinical and radiological findings, and treatment is surgical.