======  Frontal mucocele ======

[[Mucocele]]s in the [[frontal sinus]] may be asymptomatic with insidious onset or present with headaches and facial pain. Forehead (supraorbital) swelling and [[orbital cellulitis]] may also be present.

If there is orbital invasion, patients may have [[proptosis]] and [[diplopia]].

===== Radiographic features =====

==== CT ====

homogeneously low attenuating expansile lesion involving one of the ethmoid air cells
does not enhance with contrast
may demonstrate bony erosion of the sinus walls. Sinus contents tend to have a homogenous appearance
used for surgical planning
==== MRI ====

useful for defining intracranial extension or obstructing malignancy 

contents of the mucocele produce different signal intensities depending on the amount of desiccated 

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: 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 

https://radiopaedia.org/articles/frontal-mucocele-1

===== Frontal mucocele after frontal sinus transgression =====

[[Frontal mucocele after frontal sinus transgression]]