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
Treatment and prognosis
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.
- 1. Wang JH, Jang YJ, Lee BJ. Natural course of retention cysts of the maxillary sinus: long-term follow-up results. Laryngoscope. 2007;117 (2): 341-4. Laryngoscope (full text) - doi:10.1097/01.mlg.0000250777.52882.7a - Pubmed citation
- 2. Donizeth-Rodrigues C, Fonseca-Da Silveira M, GonçAlves-De Alencar AH et-al. Three-dimensional images contribute to the diagnosis of mucous retention cyst in maxillary sinus. Med Oral Patol Oral Cir Bucal.;18 (1): e151-7. Free text at pubmed - Pubmed citation
- 3. Hansen AG, Helvik AS, Nordgård S, Bugten V, Stovner LJ, Håberg AK, Gårseth M, Eggesbø HB. Incidental findings in MRI of the paranasal sinuses in adults: a population-based study (HUNT MRI). BMC ear, nose, and throat disorders. 14 (1): 13. doi:10.1186/1472-6815-14-13 - Pubmed
- 4. Bal M, Berkiten G, Uyanık E. Mucous retention cysts of the paranasal sinuses. Hippokratia. 18 (4): 379. Pubmed
- 5. Huang BY, Lloyd KM, DelGaudio JM, Jablonowski E, Hudgins PA. Failed endoscopic sinus surgery: spectrum of CT findings in the frontal recess. (2009) Radiographics : a review publication of the Radiological Society of North America, Inc. 29 (1): 177-95. doi:10.1148/rg.291085118 - Pubmed