Is a Small Mucous Retention Cyst an Indication for FESS?
No, a small mucous retention cyst is NOT an indication for functional endoscopic sinus surgery (FESS). Small mucous retention cysts are benign, self-limited lesions that typically require no treatment and can be safely observed, as they are usually asymptomatic 1, 2.
Key Decision Points
When FESS is NOT Indicated
- Small, asymptomatic cysts found incidentally on imaging do not require surgical intervention 1, 2
- Mucous retention cysts are benign lesions that appear as dome-shaped masses on CT and are commonly encountered as incidental findings 2
- The ACR Appropriateness Criteria note that retention cysts are simply imaging findings that confirm chronic rhinosinusitis but are not themselves surgical indications 3
- Most cysts resolve spontaneously and do not interfere with normal sinus function 1
When Intervention IS Required
Size-based criteria:
- Cysts occupying two-thirds or more of the total sinus volume may block natural sinus drainage and require treatment 3, 1, 4
- Large cysts require referral to otorhinolaryngology prior to any sinus procedures 3, 4, 2
Symptomatic criteria:
- Only patients with large cysts filling at least 50% of sinus space AND causing symptoms were considered surgical candidates in one study 5
- Symptoms must be present and attributable to the cyst itself, not just radiographic findings 2
Critical Assessment Required
Evaluate osteomeatal complex patency:
- The American Academy of Periodontology recommends confirming that the osteomeatal complex remains patent 1
- If the complex is patent and the cyst does not obstruct drainage, no treatment is required 1, 2
- This is the single most important factor in determining whether intervention is needed 1
Standard FESS Indications (Not Retention Cysts)
FESS is indicated for 3:
- Chronic rhinosinusitis failing medical therapy (>12 weeks of symptoms with documented inflammation)
- Acute recurrent rhinosinusitis
- Sinonasal polyposis
- Noninvasive fungal sinusitis/fungus ball
- Mucoceles (distinct from retention cysts)
- Silent sinus syndrome
- Deviated nasal septum causing obstruction
Common Pitfalls to Avoid
- Do not confuse retention cysts with mucoceles - mucoceles ARE an indication for FESS, while retention cysts are not 3, 6
- Do not operate based on imaging alone - CT findings of retention cysts do not correlate with symptom severity and are not surgical indications by themselves 3
- Avoid lowering the surgical threshold simply because FESS has minimal risk - surgery should only be pursued when goals are attainable and medical therapy has failed 7
- If a cyst is encountered during sinus surgery for other indications, small cysts can be drained intraoperatively without negative effects (96.8% implant survival rate in dental procedures) 1, 2
Management of Small Retention Cysts
Conservative approach:
- Observation is appropriate for asymptomatic small cysts 1
- Nasal saline irrigations can maintain sinus hygiene 1
- Intranasal corticosteroids if concurrent inflammatory disease is present 1
- These measures address underlying inflammation but do not directly treat the cyst 1
Recurrence rates when surgery is performed:
- Retention cysts have a 60% recurrence rate after endoscopic surgery, even with patent antrostomies 6
- This high recurrence rate further supports conservative management for small, asymptomatic cysts 6
- Recurrent cysts can be managed with office-based endoscopic marsupialization through a patent antrostomy 6