Mucosal thickening of the maxillary sinus is very common with about 50% of CBCTs. I review having a little mucosal thickening. It is not possible to know from the appearance of the soft tissue thickening alone whether this is an acute sinusitis of a few days or a chronic sinusitis of more than 3 months
If there is a fluid meniscus level, then this is usually associated with acute sinusitis. However, when there is thickening of the mucosa AND the sinus bony walls then this is indicative of chronic sinusitis.
In the axial and coronal slices below the left sinus has normal bony walls (single arrows) but the right sinus has considerable thickening of the bone. In the absence of sinus expansion or erosion, this is not a serious condition.
However, if your patient does not have a history of sinusitis then it would be prudent to tell your patient and their MD that they have signs of chronic sinusitis.
Dr. Douglas K. Benn
Oral and Maxillofacial Radiologist