Definition: A localized collection of mucous in the paranasal sinuses. This is not a true cyst as it does not have an epithelium lining.
Radiographic Features:
Location: Most commonly found in the maxillary sinuses followed by the sphenoid sinuses.
Edge: Well-defined.
Shape: Dome-shaped, attached to a border of the sinus.
Internal: Radiopaque, eventhough it is a fluid and these are generally radiolucent on radiographs, the mucous retention pseudocyst is surrounded by air (the most radiolucent entity seen on radiographs) giving it a radiopaque appearance.
Other: None
Number: May be single or multiple.
TIP: When looking at a radiopaque area in the sinus, evaluate that the borders of the radiopaque area stay within the borders of the sinus. If it appears the borders do not stay within the borders of the sinus, consider the superimposition of another entity.
Mucous Retention Pseudocyst
(arrows pointing to dome-shaped radiopaque mass on floor of the maxillary sinus)
Mucous Retention Pseudocyst
(without arrows)
Mucous Retention Pseudocyst
Mucous Retention Pseudocyst
Mucous Retention Pseudocyst
Pantomograph
