Not everything in the maxillary sinus is sinusitis: a case of a dentigerous cyst.

A 4-year-old girl presented to a medical clinic with a painless right facial swelling. The treating physician ordered a radiograph of the sinuses and received a report of "maxillary sinusitis." After appropriate antibiotic treatment, the facial swelling increased, and the mother took the child to her community pediatrician. After a period of observation and additional imaging, the diagnosis of dentigerous cyst was made. After appropriate surgical intervention, the cyst was removed, and over the ensuing 6 weeks the facial swelling gradually diminished. Dentigerous cysts, although uncommon, need to be considered in the differential diagnosis of children with painless facial swelling.