From the Guidelines
A mucous retention cyst at the base of the left maxillary sinus is a benign, fluid-filled sac that typically requires no treatment unless it causes symptoms or obstructs sinus drainage. These cysts are common, found in approximately 10% of sinus CT scans, and are different from polyps or mucoceles 1. They occur when the drainage pathway of a mucous-secreting gland becomes obstructed, often due to inflammation or previous infection, causing mucus to collect and form a cyst. According to the most recent study in 2023, mucous retention cysts are generally asymptomatic and do not impair mucociliary clearance and sinus drainage 1.
Key Characteristics of Mucous Retention Cysts
- Typically appear as dome-shaped, smooth, non-enhancing lesions on CT imaging
- Usually incidental findings that require no treatment
- Rarely cause symptoms unless they grow large enough to obstruct sinus drainage or cause pressure
- Most remain stable in size or resolve spontaneously over time
Treatment Considerations
- Treatment is generally unnecessary unless the cyst causes persistent symptoms like facial pain, pressure, or recurrent sinusitis
- Surgical removal might be considered if the cyst causes significant symptoms
- Regular monitoring with follow-up imaging is sometimes recommended for larger cysts to ensure they don't continue growing significantly 1
Important Considerations for Maxillary Sinus Elevation
- The presence of mucous retention cysts can be detected in the presurgical radiographic work-up
- These cysts can be distinguished from polyps, which tend to be pedunculated and arise from the sinus walls
- If the cyst is deflated before membrane elevation, the sinus floor can be elevated safely 1
From the Research
Definition and Diagnosis of Mucous Retention Cysts
- A mucous retention cyst at the base of the left maxillary sinus is a type of cyst that forms when the mucous membranes in the sinus become blocked, causing mucous to accumulate and form a cyst 2, 3.
- The diagnosis of mucous retention cysts can be made using imaging techniques such as panoramic radiography and cone beam computed tomography (CBCT) 3, 4.
- CBCT scans are more accurate than panoramic radiography in detecting mucous retention cysts, especially in the maxillary sinus 3.
Characteristics and Treatment of Mucous Retention Cysts
- Mucous retention cysts can be located on the walls or floor of the maxillary sinus, and their size and volume can vary 4.
- The treatment of mucous retention cysts typically involves restoring ventilation and drainage of the dependent maxillary sinus, and can include endoscopic sinus surgery (ESS) or other minimally invasive procedures 2, 5.
- A study found that endoscopic ethmoidectomy and middle meatus antrostomy without cyst detachment yielded similar outcomes with cyst extirpation through the antrostomy 2.
- Another study found that the use of a Ho-laser and endoscope can be an effective treatment for retention cysts of the maxillary sinus, with no recurrence of the cyst in any patient after a long-term follow-up period 5.