Mucosal cysts in the paranasal sinuses: long-term follow-up and clinical implications

Although mucosal cysts in the paranasal sinuses (PSMCs) are commonly detected, the long-term follow-up studies of PSMCs are sparse. This study evaluated the natural course of PSMCs and identified risk factors for the disease progression.

A total of 133 subjects with PSMCs who underwent health checkup including brain magnetic resonance imaging more than two times with an interval of ≥24 months between January 2000 and December 2009 were included. The characteristics of PSMCs were analyzed on the initial and follow-up images. Nasal symptoms, smoking status, and comorbid medical conditions were evaluated using structured questionnaires and medical records.

The mean follow-up duration was 40.38 months (range, 24.0-109.8 months). The mean size of PSMCs decreased from 15.07 to 12.73 mm. Only 8.3% of subjects showed an increase in size, whereas the size of cysts was decreased or unchanged in the remaining 91.7% of subjects. Six (4.5%) subjects complained of nasal symptoms during follow-up and subsequent sinusitis was developed in 3% of subjects. An increase in cyst size was associated with development of sinusitis (odds ratio = 45.375). Initial size of cysts >20 mm and bilateral location were significant risk factors for progression (p = 0.019 and p = 0.039, respectively).

The majority of PSMCs in this follow-up study were decreased or unchanged and most subjects were asymptomatic. Just observation is enough for most PSMCs. However, those who have a large cyst (>20 mm) or bilateral cysts at initial diagnosis were at risk for disease progression and should be regularly followed.