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

They are slow growing lesions, but mucosal and cortical integrity is preserved. 

On radiographs, they are radiopaque, dome-shaped structures with a rounded edge, located on the floor of the maxillary sinus.

Similar to radiographs, retention cysts are seen on CT/MRI as rounded dome-shaped lesions usually situated on the maxillary sinus floor. They are of low attenuation on CT where they cannot be differentiated from a small polyp.

On MRI they are usually T1 and T2 hyperintense as opposed to polyps that tend to be of low T1 signal.

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. 


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Article information

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

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