We report an extremely rare case of a fungus ball within a mucocele of the sphenoid sinus and infratemporal fossa.
A 62-year-old woman was referred for evaluation of a mass lesion in the left sphenoid sinus and infratemporal fossa. Endoscopic examination of the nasal cavity was unremarkable. Computed tomography showed a non-enhancing, expansile mass with calcifications in the sphenoid and infratemporal fossa; T2-weighted magnetic resonance imaging revealed marked hypointense signals within the sphenoid sinus mass, with an intermediate signal intensity. A presumptive diagnosis of a mucocele was made. During surgery, a profuse amount of yellow fluid was drained from the mucocele. Clay-like material was noted within the mucocele, corresponding to the hypointense magnetic resonance imaging signals; this was identified as aspergillus on histopathological examination. Radiological findings for a fungus ball within a mucocele can be similar to those for allergic fungal sinusitis, which shows mixed low and high attenuation on computed tomography and low-signal intensity on T2-weighted magnetic resonance imaging, within an expansile, cystic lesion.
Although an association between a fungus ball and a mucocele is rare in the paranasal sinuses, this disease entity should be considered in the differential diagnosis of expansile, cystic sinus lesions.