Frontoethmoidal mucocele

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A frontoethmoidal mucocele is a paranasal sinus cyst-like lesion (mucocele) lined with respiratory mucosa. The frontal and frontoethmoidal regions are reportedly the most common locations for paranasal sinus mucocele formation . They are thought to arise from obstruction of normal sinus drainage.

Clinical presentation

Mucoceles may be asymptomatic, however their ability to enlarge and erode into the adjacent intracranial and orbital regions due to ongoing mucus production and retention can cause facial pain, headaches, double vision and proptosis . Infection can lead to orbital cellulitis or meningitis .

Radiographic features

CT
  • well-circumscribed expansile mass of the ethmoidal sinus with homogenous hypoattenuation of sinus contents
  • inspissated sinus contents may appear hyperdense
  • bony erosion/remodeling may be present
  • non-enhancing with contrast
MRI
  • used to identify intracranial extension or malignancy
  • T1
    • hydrated content: low signal (most common)
    • inspissated content: high signal
  • T2
    • hydrated content: high signal (most common)
    • inspissated 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 diagnoses

  • mucus retention cyst
    • does not completely fill the sinus
    • no bony expansion
  • paranasal sinus carcinoma (generally isointense or of intermediate intensity on MR imaging sequences) 
  • aspergillus sinusitis
  • dermoid cyst
  • osteoma (rare)