The increasing use of imaging studies has lead to an increased number of incidental findings. One of these is mucous retention cysts which are found in 3 – 35% of the general population. They are dome-shaped cysts of mucous found approximately 90% of the time in the maxillary sinus. They infrequently cause symptoms. Dr. Moon and his team looked at 133 healthy individuals who were found to have a mucous retention cyst on routine MRI with a subsequent MRI in the future. They found that only 8.3% of the cysts increased in size and only 3% developed sinusitis. At follow-up, only 4.5% of the patients complained of nasal symptoms including nasal obstruction, discharge and postnasal drip. They determined that the risk factors for increase in size and potential for subsequent symptoms are bilateral mucous retention cysts and cyst size greater than 2.0 cm. These patients may warrant follow up annually. A wait and see approach is reasonable for unilateral cysts smaller than 2.0 cm.
Reference: I. J. Moon etal. Mucous cysts in the paranasal sinuses: Long-term follow-up and clinical implications. Am J Rhinol Allergy. 2011; 25(2):98-102.