Characterization of fungus ball CT-hyperdensities within maxillary and sphenoid sinuses

CT-scan hyperdensities (HD) are described in more than 60% of all paranasal sinus fungus ball (FB) cases. Two types can be distinguished according to their density: calcium and metal types. We aimed to establish the prevalence and density of the HD observed in sphenoid and maxillary sinus FB and their relation to dental factors.This retrospective study included 64 patients operated in a tertiary referral center for unilateral maxillary or sphenoid FB diagnosed by histology or mycology. Pre-operative CT scans were analyzed by three independent observers (two ENT and one radiologist).There were 45 maxillary FB and 19 sphenoid FB. 63 FB showed HD. Metal-type HD were observed in 28 maxillary FB but not in sphenoid sinuses. Among maxillary FB, the prevalence of endodontic treatment was significantly more significant on the FB side than on the healthy side (p = 0.02). The prevalence of endodontic treatment on the pathological side was more significant in the metal-type group than in the group without metal-type HD (p = 0.01). Isolated calcium-type HD were evidenced in 17 maxillary FB and 18 sphenoid FB (p = 0.019).This study highlights the existence of two different types of HD in FBs of the paranasal sinuses with an association between metal-type HD and endodontic treatments.