2. A Mucocele is an epithelium-lined mucus-filled sac
within one of the paranasal sinuses with expansion
of the sinus cavity and remodelling of the sinus
walls.
Forms – secondary to obstruction of the outflow tract
and an inflammatory process within the sinus.
Lining epithelium - pseudostratified or low-columnar
epithelium.
Bony erosion - mucocele’s epithelium is often fused
with dura or orbital periosteum.
DEFINITION
3. Frontal > ethmoid > maxillary > sphenoid sinuses
Frontal sinus mucoceles - more common - complex
and narrow drainage pathway - easily obstructed.
Mucoceles - can form in aerated structure – concha
bullosa of the middle or superior turbinate.
Obstruction of the nasolacrimal duct - lacrimal sac
mucocele / dacryocele.
SITE OF DEVELOPMENT
4. Following Sinus surgery - for chronic sinusitis and
nasal polyposis.
frontal and sphenoid mucoceles developing earlier
than maxillary sinus mucoceles.
Surgery of the frontal recess - circumferential injury
to the frontal sinus outflow tract - subsequent
stenosis – mucocele.
AETIOLOGY
5. External fronto-ethmoidectomy/ Lynch-Howarth
operation - leading cause - because of loss of lateral
bony support of the frontal recess which causes
herniation of the periorbital tissue into the frontal
sinus outflow tract.
Following endoscopic repair of skull-base fractures in
children.
Any benign or malignant tumour.
AETIOLOGY
6. Two factors are essential:
1) An obstructed sinus outflow tract
2) An inflammatory process within the sinus
Osteolytic cytokine-IL-1 and tumour necrosis factor are
present within the epithelial lining of mucoceles.
Cytokine may be the responsible for the bony erosion
in expanding mucoceles.
PATHOGENESIS
7. A visible mass - on the forehead, medial canthus or
in the gingivobuccal sulcus or cheek.
Ophthalmologic symptoms are more common than
rhinological and neurological symptoms.
The most common ophthalmologic complaints -
periorbital swelling, pain and exophthalmos.
Displacement of the orbital content - lead to limited
ocular mobility, visual disturbance and diplopia.
CLINICAL FEATURES
9. Optic neuropathy - 18% of patients - due to direct
compression of the optic nerve in the posterior
ethmoid and sphenoid sinuses.
A mucocele within a concha bullosa may present
with nasal obstruction and / or secondary sinusitis.
Epiphora and a cystic swelling in the medial canthus
suggest the presence of a dacryocele.
CLINICAL FEATURES
11. Computed tomography (CT) - homogeneous, isodense
lesion within an expanded sinus with bony
remodelling of the sinus walls.
Contrast enhancement - pyocele.
A bony defect of the lamina papyracea and / or
superomedial part of the orbital rim - fronto-
ethmoidal mucoceles.
The globe - displaced laterally and / or inferiorly - on
axial images.
RADIOLOGY
13. The sac - erosion of the posterior table of the frontal
sinus and compression of the intracranial contents.
Difficult to differentiate maxillary sinus mucoceles
from other benign or malignant lesions.
Magnetic resonance imaging (MRI) - significant bony
erosion of the posterior table of the frontal sinus or
the orbital lamina papyracea – delineate the
mucocele from adjacent soft tissue e.g. cerebral
tissue.
MRI can be misleading - variability of mucocele
content.
RADIOLOGY
16. Widely marsupialize the sac - provide permanent
ventilation and sinus drainage and to relieve pressure on
vital structure.
Cosmetic deformities settle with time - bony remodelling
takes place.
Fronto-ethmoidal mucoceles
Wide marsupialization by endoscopic and/or open
technique. Endoscopic surgery with wide
marsupialization/nasalization - the first line of treatment
- simple mucoceles.
SURGICAL MANAGEMENT
17. Modified Endoscopic Lothrop Procedure (MELP) -
more complex frontal sinus mucoceles
Combined approaches - required for laterally located
mucoceles - thick bony septation
Lynch-Howarth approach - access laterally located
frontal sinus mucoceles,to assist with the drilling
down of bony septations.
SURGICAL MANAGEMENT
18. An osteoplastic frontal flap in combination with a
MELP – mucocele lying far laterally in the frontal
sinus.
Transorbital neuroendoscopic surgery (TONES) and
the superior eyelid approach – an alternative, less
invasive approach.
Stenting remains controversial.
Stent - loose fitting to prevent circumferential
pressure.
SURGICAL MANAGEMENT
19. Maxillary sinus mucoceles
A wide middle meatal antrostomy will usually
suffice.
A partial medial maxillectomy with preservation of
the lacrimal system - to gain access to laterally
located mucoceles.
The Caldwell-Luc approach - in centres where
endoscopic surgery is not an option.
SURGICAL MANAGEMENT
20. Sphenoid sinus mucoceles
A wide sphenoidotomy and intra-nasal marsupialization.
No attempt to remove the lateral sphenoid sinus mucosa
as bony erosion place the internal carotid artery or optic
nerve at risk of injury.
Other mucoceles
Within a concha bullosa - resection of the lateral
aspect of the concha bullosa.
Dacryoceles - Endoscopic dacryocystorhinostomy.
SURGICAL MANAGEMENT
21. Great care - decompressing a large,tense frontal
mucocele that displaces the frontal lobe of the brain
as sudden expansion of the cranial contents can
disrupt the dural vessels and cause a subdural
haematoma, or disrupt the dura - cerebrospinal fluid
(CSF) leak.
Recurrence occur decades later, long-term follow-up.
COMPLICATIONS