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Sir,

Mucocoeles are common, expansile cyst-like lesions affecting the paranasal sinuses.1 The majority occur in the frontal sinus, followed by ethmoid sinus, maxillary sinus, and sphenoid sinus. They grow gradually, expand in size, and rarely produce bony destruction of the sinus walls,2 leading to orbital and ocular involvement. We report such a rare case.

Case report

A 69-year-old woman with 1-month history of right-sided facial numbness and constant aching was referred by her GP to see a neurologist. While waiting for the appointment, she developed transient double vision and mild right ptosis. She did not sustain any facial injury affecting the sinuses in the past, but gave the history of chronic right maxillary sinusitis and Caldwell–Luc operation 21 years previously. She received treatment for bronchial asthma, systemic hypertension, and Type II diabetes mellitus.

The neurologist who saw her 5 months later made an initial diagnosis of trigeminal neuralgia, and suspected that she probably sustained a transient ischaemic attack of the brain stem. Several investigations, including haematology, blood biochemistry, CT scan of the brain, and examination of the CSF, were within normal limits.

Several months later, there was recurrence of double vision and worsening of her symptoms. This time the neurologist noticed right ptosis, proptosis, and limited ocular movement, but found no other neurological abnormalities. She was admitted for an urgent CT scan of the orbit and paranasal sinuses. This showed an extensive mucocoele of the right maxillary sinus extending into the orbit with optic nerve displacement. At this point, the patient was referred to see an ENT surgeon. An urgent ophthalmologic consultation was also sought.

The ophthalmologist found that her right visual acuity was 6/36 (Snellen's), with no clinical signs of optic nerve compression. She had right infraorbital numbness, complete upper lid ptosis, nonaxial proptosis, and severe restriction of ocular movement. There were no signs of uveitis and the intraocular pressure was normal. The right fundus showed inferior indentation, macular choroidal folds, and a normal optic disc. The left eye was normal with an unaided visual acuity of 6/9. An ultrasound B scan of the right eye showed a large orbital mass indenting the inferior aspect of the eyeball (Figure 1).

Figure 1
figure 1

(a) and (b): MRI show complete opacification of right maxillary sinus with expanding mass in all directions. (c) Ultrasound B scan with large orbital mass indenting the inferior aspect of the eyeball.

MRI of the orbit and the sinuses revealed complete opacification of the right maxillary antrum with an expanding mass in all directions. A bulge in the orbital floor resulted in the elevation of the globe and proptosis (Figure 1a, b). These findings clearly suggested the diagnosis of maxillary mucocoele and it was decided to remove the lesion surgically.

The operation was performed immediately under general anaesthesia by the ENT surgeons who drained the fluid and removed the mucocoele completely through a wide inferior antrostomy. An immediate correction of the proptosis was noted at the end of the operation. The right eye on the first day postoperatively showed that there was an improvement in the visual acuity (6/9), complete resolution of diplopia, full restoration of ocular movement and ptosis, and disappearance of the macular choroidal folds and inferior global indentation. The aspirated serous fluid was found to be sterile and the biopsy report confirmed benign cystic inflammatory lesion consistent with mucocoele of the maxillary sinus.

Comment

Here is a patient with right-sided maxillary mucocoele, which expanded into the orbit producing facial pain, restricted ocular movement, nonaxial proptosis, deformity of the eyeball, and reduced vision. Some common causes producing these features are considered and the management of mucocoele discussed.

The common causes of unilateral facial pain in the elderly include trigeminal neuralgia, atypical facial pain, postherpetic neuralgia, dental causes, sinusitis, ocular or orbital inflammation, or temporal arteritis. Trigeminal neuralgia is characterised by paroxysmal attacks of severe, short, sharp pain affecting one or more divisions of the trigeminal nerve. It is often superimposed by constant ache and the attacks precipitated by touching a ‘trigger spot’. Atypical facial pain is dull and diffuse. Other causes include pathologies involving ears or even cerebellopontine angle tumours.3 It is unlikely that this patient suffered a transient ischaemic attack of the brain stem. This condition is characterised by vertigo, vomiting, dysarthria, ataxia, diplopia, and hemisensory loss with full recovery in 24 h.4 The causes of unilateral proptosis with oculomotility problems include thyroid eye disease, orbital inflammatory disease, or orbital apex syndrome.

Mucocoeles are common expansile cyst-like lesions affecting paranasal sinuses. The majority occur in the frontal sinus (60%), followed by ethmoidal sinuses (30%), maxillary sinuses (10%), and rarely the sphenoidal sinuses.5 The most common cause of mucocoele of the maxillary sinus is trauma: accidental or iatrogenic (Caldwell–Luc procedure).6 It can also occur in non-Hodgkin's lymphoma.7

The diagnosis of mucocoele is made on the basis of symptoms, imaging and surgical exploration and histological confirmation. The most consistent symptom is dull maxillary facial pain. Other symptoms include swelling and/or numbness of the cheek, poorly localised pain or tenderness, nasal obstruction, visual impairment, diplopia, and dental problems.8 High-resolution CT scan will show homogenous lesions, which are isodense with brain and no contrast enhancement, unless infected. There are clearcut margins of bone erosions occurring in the sinus walls. In malignancy, the mass is likely to be irregular in shape, with erosion and destruction of sinus walls. In sinusitis or retention cyst, there is no bone destruction.8

The treatment of mucocoele is surgical removal by the ENT surgeons.9 Some paranasal sinus mucocoeles can encroach the orbit and cause ocular compression. This case clearly demonstrates how relevant it is to refer all patients with ptosis and oculomotility problems to an ophthalmologist very early during their presentation.