Dentigerous cyst with fistula to oral cavity
Findings:
Axial and Coronal facial CT demonstrate an expansile cystic lesion within the base of the right maxillary sinus. At the superior aspect of the lesion, the crown of an unerupted tooth projects into the lumen. The floor of the lesion is dehiscent with direct communication to the oral cavity. The lesion contains mixed complex fluid density and gas.
Differential Diagnosis:
Dentigerous cyst, periapical cyst, ameloblastoma.
Discussion:
The crown of an unerupted tooth points in to the lumen of a dentigerous cyst which makes the other possibilities above unlikely. Superinfection is common if there is a communication to the oral cavity.