Paranasal sinuses retention cysts

Retention cysts of paranasal sinuses are benign lesions usually discovered incidentally on a plain sinus radiograph or cross-sectional imaging of the head. They do not usually cause symptoms. 

They are also referred to as mucous retention cysts.

It is difficult to estimate their true incidence since most studies report findings of retention cysts on imaging performed for unrelated symptoms. However, an incidence of 29 -31% has been reported in studies on adults undergoing brain MRI 3,4.

Although usually discovered incidentally and asymptomatic, retention cysts can cause a headache, peri-orbital pain and nasal obstruction. They may occasionally present with repeated episodes of sinusitis.

Retention cysts represent obstructed submucosal mucinous glands within the paranasal sinus 5.

Retention cysts are seen on imaging as rounded dome-shaped lesions often situated on the maxillary sinus floor. They are slow growing lesions, but mucosal and cortical integrity is preserved. 

Radiopaque dome-shaped lesion with a rounded edge, often seen on the floor of the maxillary sinus.

Low attenuation well-defined rounded lesion within the paranasal sinus. Unless extremely large, the affected paranasal sinus usually remains aerated.

  • T1: variable, often intermediate to hypointense depending on the protein content
  • T2: hyperintense

Mostly no treatment is indicated, because of their high spontaneous regression rate 1,2. If symptomatic or causing nasal obstruction they can be surgically resected endoscopically. 

  • sinonasal polyp: may be indistinguishable on CT and MRI, but mucosal retention cyst do not extend to the nasal cavity
  • paranasal sinus mucocele: air within the affected paranasal sinus rules out a mucocele 
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Article information

rID: 22374
System: Head & Neck
Tag: refs, stub
Synonyms or Alternate Spellings:
  • Retention cyst of the maxillary sinus
  • Mucous retention cysts
  • Mucous retention cyst

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