Incidentally discovered asymptomatic extrasinusal mucocele of the sphenoid greater wing: A case report and review of differential diagnoses

Abstract

Extrasinusal mucoceles are exceptionally rare cystic lesions that arise outside the paranasal sinuses and may pose diagnostic challenges, particularly when incidentally detected in atypical locations. Their imaging appearance can overlap with other cystic skull-base and intracranial lesions. We report the case of a 45-year-old woman with an asymptomatic extrasinusal mucocele incidentally discovered on CT performed during follow-up of a peritonsillar abscess. Imaging revealed a well-defined expansile cystic lesion in the spheno-temporo-orbital region, causing cortical thinning without surrounding intracranial edema or diffusion restriction. MRI demonstrated homogeneous fluid signal intensity, thin peripheral enhancement, and absence of solid components. Based on these radiological findings, an imaging-based diagnosis of a probable extrasinusal mucocele was favored. As the patient declined surgical intervention, a conservative approach with regular clinical follow-up every 3 months and annual MRI surveillance was adopted. At the most recent follow-up, the lesion remained radiologically stable without interval growth or new symptoms. This case underscores the importance of considering extrasinusal mucocele in the differential diagnosis of skull-base cystic lesions.