What is the management of a maxillary sinus floor retention cyst?

Management of Maxillary Sinus Floor Retention Cysts

Mucous retention cysts of the maxillary sinus generally do not require treatment unless they are symptomatic or interfere with planned procedures, as most will spontaneously regress or remain stable over time. 1

Assessment and Diagnosis

• Mucous retention cysts are benign lesions that appear as radiopaque, dome-shaped masses, typically originating from the sinus floor and are easily detected in presurgical radiographic evaluation 2
• These cysts can be distinguished from polyps (which tend to be pedunculated and arise from sinus walls) and are usually filled with yellow serous fluid, which is pathognomonic for this lesion 2
• Proper differential diagnosis should include distinguishing retention cysts from odontogenic cysts, sinusitis, aspergillosis, and mucocele through clinical symptoms and cone-beam computed tomography (CBCT) 3

Management Algorithm

For Asymptomatic Cysts:

• Small to moderate-sized asymptomatic cysts require no intervention and can be managed with a "wait and see" approach, as most will spontaneously regress or show no significant change in size over time 1
• For patients undergoing sinus floor augmentation procedures, mucous retention cysts do not require any further investigation if the cyst does not interfere with the osteomeatal complex or is located in a different area (e.g., distal wall of the sinus) 2

For Symptomatic Cysts or Those Interfering with Procedures:

• Small cysts encountered during sinus floor augmentation can be effectively drained at the time of surgery without negative effects on outcomes 2
• Aspiration or deflation of the cyst before membrane elevation allows the sinus floor to be elevated safely during augmentation procedures 2
• Large cysts (occupying two-thirds or more of the sinus volume) may require treatment by an otorhinolaryngologist prior to any sinus procedures, as they could potentially block sinus drainage if the membrane is elevated 2, 4

Surgical Approaches When Treatment is Indicated:

• Endoscopic removal is the preferred surgical approach for symptomatic cysts with a low recurrence rate (approximately 3%) and minimal complications 5
• The endoscopic approach has several advantages over the traditional Caldwell-Luc procedure, including:
  • Shorter operative time (34 minutes vs. 44 minutes) 6
  • Significantly less post-operative pain (84.2% of endoscopically treated patients had no pain vs. only 5.3% in the Caldwell-Luc group) 6
  • Shorter hospital stay (3.6 days vs. 5.8 days) 6

Special Considerations for Dental Implant Procedures:

• During sinus lift procedures, retention cysts can be managed based on size and location:
  • Small cysts can be left in place if they don't interfere with the procedure 3
  • Larger cysts may be removed by the dental surgeon during antral augmentation as one of the stages of the operation 3
• The cumulative implant survival rate (96.8%) is not affected by the presence and intrasurgical draining of mucous retention cysts 2

Potential Complications and Monitoring:

• Recurrence is possible but uncommon (approximately 3%) after endoscopic removal 5
• When the cyst is elevated during sinus procedures, it could potentially impact the natural ostium, blocking mucosal drainage and possibly causing inflammatory or infective conditions 2
• In rare cases, severe facial pain may be associated with maxillary sinus retention cysts, and surgical removal may provide symptom resolution in carefully selected cases 7

Clinical Pearls and Pitfalls:

• Avoid maxillary sinus overfilling during augmentation procedures when a cyst is present, as this could lead to technical errors 2
• Always interpret radiologic findings along with proper sinus history and clinical symptoms 2
• Computer tomography should be performed before any surgical procedure to properly evaluate the cyst and surrounding structures 6
• Interdisciplinary collaboration between dental surgeons and otorhinolaryngologists is essential when managing complex cases 3