Sphenoid sinus mucosal thickening occurs when the lining of the sinus cavities swell. Cysts filled with mucous can form in the cavities when a gland becomes obstructed and swells. Prior infections can cause swelling, and swelling can also lead to an infection.
Not all mucus swelling involves symptoms or concern, according to findings published by the Fitzsimons Army Medical Center Department of Radiology. The study looked at MRI results and symptomology reports for 128 patients. Based on the findings, the team concluded that mucosal swelling up to 3 mm is a common occurrence that does not usually result in clinical findings or in patients reporting symptoms.