Figure 1. Drawings illustrate aberrant development of the nasofrontal region leading to the formation of various midface masses. Schematic A shows that frontonasal encephaloceles form when the fonticulus nasofrontalis remains patent. Schematic B shows that nasal gliomas form when the dural diverticulum involutes late or only proximally through the foramen cecum, leaving sequestered neurogenic tissue that may be connected to the intracranial content by a fibrous stalk. As shown in schematic C, dermal sinuses result from a lack of involution of the dural diverticulum through the foramen cecum. Dermoid or epidermoid cysts may form along the dermal sinus tract due to desquamation of tissue lining the tract. (Reprinted, with permission, from reference 6.)