CLINICAL STUDY

Fungal Ball Within Onodi Cell Mucocele Causing Visual Loss Yong-Il Cheon, MD,* Sung-Lyong Hong, MD,* Hwan-Jung Roh, MD, PhD† and Kyu-Sup Cho, MD, PhD* Abstract: The Onodi cell is a pneumatized posterior ethmoid cell located laterally and superiorly to the sphenoid sinus and closely related to the optic nerve. A mucocele is a benign, expansile, cystlike lesion of the paranasal sinuses that is filled with mucoid secretion. Therefore, optic neuropathy caused by an infected mucocele in an Onodi cell is uncommon. Furthermore, fungal infection superimposed on an Onodi cell mucocele is extremely rare and has not been reported previously. Here, we describe the first case of fungal ball within Onodi cell mucocele causing visual loss, which was completely removed via transnasal endoscopic approach. Key Words: Aspergillosis, ethmoid sinusitis, mucocele, vision, low, endoscopy (J Craniofac Surg 2014;25: 512–514)

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ucoceles are benign, expansile, cystlike lesions of the paranasal sinuses that is filled with mucoid secretions and lined by respiratory epithelium.1 Most mucoceles often occur in the frontal and anterior ethmoid sinus rather than the posterior ethmoid and sphenoid sinus.2 Therefore, mucoceles involving Onodi cell, the most posterior ethmoid cell, are rare.3 When mucoceles become infected mostly by bacteria, a mucopyocele may develop. However, paranasal sinus mucoceles with superimposed fungal infections are extremely rare, especially in the Onodi cell. We report the first case of fungal ball within Onodi cell mucopyocele causing visual loss, which was completely removed via transnasal endoscopic approach. This study was approved by the institutional review board of Pusan National University Hospital.

CLINICAL REPORT A 60-year-old man visited the outpatient clinic for evaluation of a mass lesion in the left posterior ethmoid sinus with headache and blindness of the left eye. He was seen by a neuro-ophthalmologist,

From the *Department of Otorhinolaryngology and Biomedical Research Institute, Pusan National University School of Medicine, Pusan National University Hospital, Busan, Republic of Korea; and †Department of Otorhinolaryngology and Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea. Received November 29, 2013. Accepted for publication December 28, 2013. Address correspondence and reprint requests to Dr. Kyu-Sup Cho, Department of Otorhinolaryngology, Pusan National University School of Medicine, Pusan National University Hospital 1–10 Ami-dong, Seo-gu, Busan 602–739, Republic of Korea; E-mail: [email protected] The authors report no conflicts of interest. Copyright © 2014 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000000678

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FIGURE 1. Initial preoperative orbit MRI scans. The MRI scans show an oval-shaped, expansile, heterogenous mass compressing the optic nerve in the Onodi cell displaying focal, low signal intensities within the mass on T2WI (A) and peripheral enhancement on postcontrast T1WI (B). Left sphenoid sinusitis is noted.

who found visual loss to no light perception on the left. There was no history of nasal surgery. He had brain infarction for 5 years, and he has been recovered. Two years ago, the patient presented to the neurology outpatient clinic with gradually decreased visual acuity for several months. Orbit magnetic resonance imaging (MRI) was performed and showed an oval-shaped mass compressing the left optic nerve in the Onodi cell of the left posterior ethmoid sinus displaying heterogenous signal intensity on T1-weighted images (T1WIs) and T2-weighted images (T2WIs) with mild peripheral enhancement. In addition, left sphenoid sinusitis with homogenous high signal intensity was also observed (Fig. 1). However, the patient refused to have any treatment. Endoscopic examination of the nasal cavity was unremarkable. A computed tomography (CT) of the paranasal sinuses showed a dense homogenous, oval-shaped mass in the posterior ethmoid cell, which was superior to the sphenoid sinus extending superolaterally around the left orbital apex. The bony defects of the lamina papyracea and the skull base were noted (Fig. 2). A transnasal endoscopic sphenoethmoidectomy was performed. After widening of the

FIGURE 2. Preoperative paranasal sinus CT. Axial (A) and coronal (B) images show a cystic, homogenous, thin-walled mass in the Onodi cell (white arrow) and opacification in the left sphenoid sinus (black arrow).

The Journal of Craniofacial Surgery • Volume 25, Number 2, March 2014

Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.

The Journal of Craniofacial Surgery • Volume 25, Number 2, March 2014

FIGURE 3. Intraoperative endoscopic finding. A, A fungal ball is shown in an Onodi cell mucocele. B, After removal of the fungal ball in an Onodi cell and purulent secretions in the sphenoid sinus (S), bony dehiscence is noted in the lamina papyracea (LP) and the skull base (SB).

mucocele wall, a large amount of a yellow, purulent secretion, together with a cheesy, claylike material suggestive of fungal ball, was found surrounding the optic nerve in an Onodi cell. The fungal ball and purulent secretions were successfully removed. Bony dehiscence was noted around the skull base, and pulsating dura mater was detected (Fig. 3). Histopathologic examination of the cheesy, claylike material was consistent with an aspergilloma (Fig. 4). This case was diagnosed as a fungal ball within a mucocele of the Onodi cell. The patient had an uneventful recovery and headache disappeared, but vision loss has not improved. Endoscopic examinations and CT performed 6 months postoperatively showed no evidence of recurrence (Fig. 5).

DISCUSSION An Onodi cell is the most posterior ethmoid cell that has pneumatized laterally and superiorly to the sphenoid sinus.4 The incidence of Onodi cell varies from 8% to 13% on radiologic findings, and its clinical importance lies in its close proximity to the optic nerve.5 This explains the devastating loss of vision in our case with an infected mucocele of the Onodi cell. The coexistence of a fungal ball within a mucocele can be explained by the hypothesis that fungal ball within the sinus causes recurrent infection, which leads to obstruction of the sinus ostium and the development of a mucocele. The pathophysiologic mechanism of optic neuropathy is likely a combination of physical compression and inflammation.3,6 According to theory, cleavage of the optic canal wall or bone resorption occurs, the optic nerve is directly compressed by the mucocele, and ischemia of the nerve and venous congestion develop. The second theory postulates that inflammation occurs because of an infection in the mucocele and spreads to the nerve via a cleavage in the

Fungal Ball Within Onodi Cell Mucocele

FIGURE 5. Postoperative paranasal sinus CT. Axial (A) and coronal (B) images at 6 months postoperatively show no evidence of recurrence.

optic canal wall or via a bone resorption site. In our patient, gross observation during the operation did not reveal the optic nerve to be exposed, and for this reason, it can be surmised that inflammation had spread via a cleavage in the optic canal wall or in the small site of bone resorption caused by the mucocele. Furthermore, inflammatory products spread through the vascular or lymphatic vessels could be a cause for optic neuropathy. Radiologic imaging modalities, such as CT and MRI, are important in preoperative diagnosis and planning.3 Mucoceles often present as homogenous opacifications on CT, hypointense lesions on T1WIs, and hyperintense lesions on T2WIs. In contrast-enhanced MRI images, the sinus mucosa enhances as a thin line surrounding the mucocele. However, the MRI appearance of mucoceles varies depending on their protein concentration, which changes over time. A higher protein content of mucocele mucus may increase the T1 signal intensity on MRI, with contrast enhancement localized to the peripheral cystic walls.1,3 On T2WI, the signal intensity usually remains high but may be decreased as the contents become inspissated.7 In our case, CT showed a cystic, homogenous, thin-walled mass in the Onodi cell with bony erosion. Magnetic resonance imaging showed a mass with a high signal intensity on T1WI and an intermediate signal intensity on T2WI. On the basis of radiologic findings, a mucocele with a high protein content was initially suspected. However, the focal, low signal intensities seen within the mass on T2WI showing heterogenous signal intensity on T2WI presented a diagnostic challenge. During surgery, fungal ball was noted within the mucocele, which corresponded to the low signal seen on T2WI. The treatment of fungal ball within Onodi cell mucocele is drainage and restoration of sinus ventilation via transnasal endoscopic approach. In general, the prognosis is poor when the preoperative degree of visual impairment is high or when its onset is very sudden. Although no clear duration of visual loss is predictive of visual outcome, in cases with a mild to moderate degree of visual impairment and gradual progression, the prognosis depends on the time from onset until surgery is performed.1,8 Therefore, immediate endoscopic decompression of the optic nerve should be attempted because the prognosis may worsen after 1 to 2 months of symptoms.1

CONCLUSIONS

FIGURE 4. Histopathologic findings of fungal ball in an Onodi cell. A, A fungal ball (aspergilloma) is composed of tangles of acutely branching thin septated hyphae (hematoxylin and eosin, 400). B, Gomori methenamine silver staining shows much more clear delineation of fungal hyphal structures with fungal ball (400).

Although an association between a fungal ball and a mucocele is extremely rare in an Onodi cell, superimposed fungal infection of Onodi cell mucocele should be considered in the differential diagnosis of optic neuropathy caused by mucocele. Furthermore, immediate endoscopic decompression of the optic nerve and complete removal of fungal ball should be attempted to ensure the return of normal visual function.

© 2014 Mutaz B. Habal, MD

Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.

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REFERENCES 1. Victores A, Foroozan R, Takashima M. Recurrent Onodi cell mucocele: rare cause of 2 different ophthalmic complications. Otolaryngol Head Neck Surg 2012;146:338–339 2. Klink T, Pahnke J, Hoppe F, et al. Acute visual loss by an Onodi cell. Br J Ophthalmol 2000;84:801–802 3. Toh ST, Lee JC. Onodi cell mucocele: rare cause of optic compressive neuropathy. Arch Otolaryngol Head Neck Surg 2007;133:1153–1156 4. Stammberger HR, Kennedy DW. Anatomic Terminology Group. Paranasal sinuses: anatomic terminology and nomenclature. Ann Otol Rhinol Laryngol Suppl 1995;167:7–16

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5. Kitagawa K, Hayasaka S, Shimizu K, et al. Optic neuropathy produced by a compressed mucocele in an Onodi cell. Am J Ophthalmol 2003;135:253–254 6. Nickerson JP, Lane AP, Subramanian PS, et al. Onodi cell mucocele causing acute vision loss: radiological and surgical correlation. Clin Neuroradiol 2011;21:245–248 7. Lim CC, Dillon WP, McDermott MW. Mucocele involving the anterior clinoid process: MR and CT finding. AJNR Am J Neuroradiol 1999;20:287–290 8. Yumoto E, Hyodo M, Kawakita S, et al. Effect of sinus surgery on visual disturbance caused by spheno-ethmoid mucoceles. Am J Rhinol 1997;11:337–343

© 2014 Mutaz B. Habal, MD

Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.

Fungal ball within Onodi cell mucocele causing visual loss.

The Onodi cell is a pneumatized posterior ethmoid cell located laterally and superiorly to the sphenoid sinus and closely related to the optic nerve. ...
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