Keywords
ethmoid sinus - sinus mucocele - hemianopsia
Introduction
Paranasal sinus mucoceles are benign indolent cystic lesions filled with mucus and
recovered by respiratory epithelium occurring due to an obstruction of sinus ostia.[1]
[2] They are locally expansive and destructive, causing resorption, erosion, and bone
remodeling.[2]
Mucoceles are often unilateral and may involve more than one sinus. Most commonly
affected are the frontal (60 to 65%) and ethmoidal (20 to 30%) sinuses, followed by
the maxillary (10%) and sphenoidal (2 to 3%) sinuses.[3]
Case Report
The patient was a 46-year-old woman with diagnosis of severe myopia since childhood,
with routine periodic monitoring. There were no other comorbidities. In 2007, a sudden
nasal hemianopsia appeared in the left eye. After further ophthalmologic investigation,
she was referred for neurologic imaging study. A computed tomography (CT) scan showed
soft tissue occupying some of posterior left ethmoid cells, adjacent to the lamina
papyracea. In this topography, it presented tenuous irregularities that could correspond
to erosion of its walls ([Figs. 1] and [2]). Magnetic resonance imaging (MRI) showed hyperintense image in T2 sequence, with
no significant enhancement by contrast ([Figs. 3] and [4]).
Fig. 1 Coronal bone computed tomography image shows soft tissue content occupying some posterior
left ethmoid cells, adjacent to the lamina papyracea.
Fig. 2 Axial bone computed tomography reveals irregularities possibly corresponding to erosion
of lamina papyracea.
Fig. 3 Axial magnetic resonance imaging sequences show hyperintense signal in the corresponding
tissue.
Fig. 4 Axial magnetic resonance imaging sequences show hyperintense signal in the corresponding
tissue.
Possible ethmoidal mucocele with orbital involvement and optic nerve injury was considered
during ear, nose, and throat evaluation. Surgical treatment was proposed then. For
personal reasons, the patient opted not to be operated at the time, and she returned
2 years later with the same ophthalmic presentment. Another CT scan identified just
slight thickening of the mucous lining and hypodense content in some posterior ethmoid
cells, bilaterally, mostly in left side, with no difference in papyraceous plate ([Fig. 5]).
Fig. 5 Axial bone computed tomography reveals thickness of mucous lining and small content
in posterior ethmoid cells, bilaterally, mostly in the left side.
With no specific treatment performed, tomographic study in 2012 showed no lesions,
but ophthalmic involvement remained unchanged ([Figs. 6] to [7]
[8]). Current eye examination found vision in the right eye of 20/100 and in the left
eye, finger counting (temporal).
Fig. 6 Coronal bone computed tomography with normal findings.
Fig. 7 Axial bone computed tomography with normal findings.
Fig. 8 Another axial bone computed tomography with no abnormalities.
Discussion
Paranasal sinus mucoceles are more common during the third and fourth decades, with
slight predominance of male sex.[2] It is mainly related to previous sinus surgery, face trauma, and chronic rhinosinusitis.[4] Nasal tumors, fibrous dysplasia, and cystic fibrosis are rarely associated causes,
and the last one should be remembered in cases in children.[5]
[6]
Paranasal sinus mucoceles are oligosymptomatic, slow-growing, expansive lesions. However,
they may be locally aggressive and evolve to neurologic, skin, or eye complications.
Substances such as prostaglandin E2 and collagenase are detectable in the capsule
of the mucocele and seem to be related to its ability to resorb bone.[3]
[7]
Imaging study allows easy identification of the injury and its extent. CT scan is
the ideal method for detecting bone erosion and remodeling. MRI should be performed
when intracranial invasion is suspected.[8]
Usually, ocular complications arise from absorption of papyraceous lamina, with possibility
of proptosis due to displacement of the eyeball by the mucocele. Depending on the
extent of bone erosion, the optic nerve can be compressed or stretched, resulting
in transient or permanent visual impairment.
Surgical treatment must always be performed and, when done in a timely manner, may
avoid optic nerve injury or even allow it to recover in cases of mild involvement.
Nasal endoscopic surgery has developed in the latest decades, and the endonasal approach
is widely used. It has fewer postsurgical complications and minimal mucosal damage
and offers a better postoperative view for close observation.[7]
[8]
