Objectives: Retention cysts of the maxillary sinus are an incidental finding on radiographs. These cysts usually appear as rounded, dome-shaped, soft tissue masses, most often on the floor of the maxillary sinus. The aim of this study was to investigate the long-term natural course of retention cysts of the maxillary sinus.
Methods: Between November 1997 and October 2002, 40 patients were incidentally found to have retention cysts of the maxillary sinus on Waters view films. Seventeen of these patients were followed for 38 to 102 (mean, 60) months. Medical records, endoscopic nasal examinations, and Waters view of all 40 patients were reviewed. The size of each retention cyst and the ratio of cyst size to antral size were measured.
Results: Of the 40 patients, 21 (52.5%) had cysts in the left maxillary sinus, 17 (42.5%) had cysts in the right maxillary sinus, and 2 (5%) had cysts in both sinuses. Thirty of the 43 (69.7%) cysts appeared to arise from the floor of the sinus. Cyst size ranged from 108 mm to 1,001 mm, and the ratio of cyst size to antral size ranged from 12.8% to 96.9%, as measured on Waters view. Follow-up Waters view films in 17 patients showed that seven cysts disappeared completely, two decreased in size, four showed no significant change in size, and five increased in size.
Conclusions: Most retention cysts of the maxillary sinus spontaneously regressed or showed no significant change in size over the long term. These findings suggest that, in the absence of associated complications, "wait and see" may be the appropriate management strategy for these retention cysts.