Cysts, one of the principal maxillary sinus disorders, are divided into extrinsic and intrinsic categories.

Extrinsic cysts are of dental (odontogenic) and non-dental (non-odontogenic) origin. The dental cysts are generally oval or curved. The dental cysts displace borders of the sinus affected. The sinus wall fuses with the cyst cortex. The cyst expands, whereas the sinus size reduces. A new radiopaque border divides the sinus air space and the cyst lumen, separating the cysts from the sinus. Some times, almost entire sinus is affected and the small remaining part of the sinus stays on the cyst. Expanding cysts may affect the maxillary antrum walls.

The dental cysts, the most common cysts found in the maxillary sinuses, are dentigerous and radicular. When fluid accumulates between the eroded enamel epithelium and crown of a tooth, a dentigerous cyst surrounds the crown. The cyst is usually related to third molar region. These cysts elevate the floor of the maxillary sinus. The tooth displacement is a common symptom. The dentigerous cysts are grouped into kerato and primordial cysts.  The kerato cyst is non-inflammatory cyst. The cyst grows on the dental lamina and may expand into the maxillary sinus. The kerato cyst is generally found in mandibular ramus region.

The radicular cyst develops in the maxilla bone. The cyst may reach to the maxillary sinus. A big cyst may fully cover the sinus and as a result, it is difficult to differentiate between the cyst and other sinus symptoms. The cyst raises the sinus floor, causing a halo. Inflammation of the epithelial cells found in the periodontal ligament causes radicular cysts. These cysts are associated with first molar, canine and lateral incisor teeth.

The non-dental cysts are further divided into anesurysmal bone cyst (ABC), globulomaxillary and traumatic. The globulomaxillary cysts may change or hide the maxillary sinus’ anterior recess and the nasal fossa border.

Mucus retention cyst, the intrinsic and non-dental cyst, is also referred to as benign mucosal antral cyst, pseudocyst and mesothelial cyst. The lateral wall and antral floor of the maxillary sinus is affected. The maxillary sinus symptoms include numbness and fullness of the cheeks, pain in the face part near the sinus and the teeth, and localized faint pain in the antral area. If cyst obliterates the entire sinus, it may lead to postnasal drip. The other sinus symptoms are headache, fullness and stuffiness. If a retention pseudocyst enlarges and occupies the entire sinus cavity and patient blows the nose or sneezes, the cyst ruptures due to change in pressure.