A frontal mucocele is a paranasal sinus mucocele in a frontal sinus and is the most common location of all the paranasal sinus mucoceles 1.
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Clinical presentation
Mucocoeles in the frontal sinus may be asymptomatic with insidious onset or present with headaches 2 and facial pain. Forehead (supraorbital) swelling and orbital cellulitis 3 may also be present.
If there is orbital cavity invasion, patients may have proptosis, hypotropia, and diplopia.
Radiographic features
CT
- homogeneously hypodense, expansile lesion within an airless frontal sinus 4
- does not enhance with contrast
- may demonstrate remodeling, thinning, or erosion of the sinus walls
- used for surgical planning
MRI
- useful for defining intracranial extension or obstructing malignancy 1
- contents of the mucocele produce different signal intensities depending on the amount of desiccated 4
-
T1
- water-rich content: low signal (most common)
- protein-rich content: high signal
-
T2
- water-rich content: high signal (most common)
- protein-rich content: low signal
- may look like an air-filled sinus in advanced disease
- T1 C+ (Gd): enhancement, if present, only occurs at the periphery
- DWI/ADC: variable
Differential diagnosis
Possible considerations include:
-
allergic fungal sinusitis
- no bony expansion
-
mucus retention cyst
- does not completely fill the sinus
- no bony expansion
- sinonasal polyposis
- fibrous dysplasia 5