CT approach to benign nasopharyngeal masses.

The physical characteristics of the fascial planes of the nasopharynx provide a basis for categorizing growth patterns of the more common benign nasopharyngeal masses. Lymphoid hyperplasias are confined to the surface by the very dense pharyngobasilar fascia that lies beneath the submucosa. It takes a very aggressive process to cross this fascial plane. More laterally throughout the paranasopharyngeal space the loose areolar nature of the buccopharyngeal fascia permits benign tumors in this space to assume a spherical configuration. The carotid sheath is also a loose areolar arrangement that permits free movement of the carotid artery in the neck. Juvenile angiofibromas permeate natural foramina, displace bony septa, and extend widely but do not invade the carotid sheath. Neurogenic tumors and paragangliomas are intimately associated with contents of the carotid sheath; therefore, they obliterate the low density regions surrounding the carotid vessels.