|Year : 2013 | Volume
| Issue : 3 | Page : 159-162
Giant subperiosteal orbital Schwannoma with luxated globe
Vijay D Khetan
Rajeshwar Eye Surgery Child Care, Akola, Maharashtra, India
|Date of Submission||28-May-2013|
|Date of Acceptance||24-Jun-2013|
|Date of Web Publication||23-Aug-2013|
Vijay D Khetan
Rajeshwar Eye Surgery Child Care, Birla Road, Ramdas Peth, Akola - 444 005, Maharashtra
Source of Support: None, Conflict of Interest: None
A middle-aged Indian female patient presented with unilateral chronic painless progressive giant orbital tumor of 15 years duration causing complete anterior globe luxation. Roentgenograms revealed enlarged orbital cavity with soft-tissue mass shadow. Computed tomography showed a giant orbital cyst filling the entire orbit displacing the orbital contents outside with intact, but thinned orbital walls. The lesion was solitary and well-encapsulated. Surgical excision using combined anterior and lateral orbitotomy approach completely removed the subperiosteal cyst and associated cosmetic blemish with recovery of extra-ocular movements. Histology confirmed the diagnosis of Schwannoma with massive cystic degeneration and areas of calcification.
Keywords: Orbital cyst, Schwannoma, subperiosteal
|How to cite this article:|
Khetan VD. Giant subperiosteal orbital Schwannoma with luxated globe. J Clin Ophthalmol Res 2013;1:159-62
Orbit is a pandora's box as it contains a large variety of tissues that have the potential to develop a wide spectrum of diseases.  Orbital cystic mass lesions accounts for approximately 17% to 20% in various series published. , Schwannoma account for approximately 1% of all orbital tumors.  This uncommon benign orbital tumor arises from Schwann's cells in the peripheral nervous system.  Advanced cystic degeneration and calcification in Schwannoma is an even more rarely reported. 
We report a case of middle-aged Indian female patient with a subperiosteal located giant orbital cyst with completely luxated globe. The tumor removed surgically using combined anterior and lateral orbitotomy approach proved to be a benign Schwannoma on histopathology with areas of calcification and massive cystic degeneration.
| Case Report|| |
A 45-year-old middle-aged female presented to the out-patient department with painless progressive enlarging swelling over the right eye (RE) with progressive globe prominence and diminution of vision of 15 years duration. There was no history of diplopia, headache, vomiting, chronic sinusitis, trauma or treatment.
Visual acuity was finger counting (FC) close to face in RE and 6/6 in the left eye. On gross examination, a tense fluctuant smooth surfaced mass was felt below the right upper eyelid arising from the orbit pushing the globe forward and downward completely out of the socket [Figure 1]. The mass measured 3.0 cm outside the orbital margin, about 4.0 cm in width and was about 5.0 cm in height over the luxated globe [Figure 2]. The upper eyelid was commensurately stretched over the mass and was able to cover the eyeball along with the stretched lower eyelid [Figure 3].
On palpation, the orbital margins were intact and the posterior edge of the mass could not be reached. The swelling was non-pulsatile, non-tender and non-reducible.
Valsalva's maneuver test was negative. Extra ocular movements (EOM) were present, but grossly restricted in all directions for RE.
There was no local lymphadenopathy, any nodule or pigmented spots noted elsewhere. Slit lamp examination of RE showed a healthy conjunctiva with clear cornea. The anterior chamber was quite. Gross relative afferent pupillary defect was present. Dilated fundus examination showed normal appearing optic disc with dilated tortuous retinal vessels.
There were chorioretinal folds with pigmentary degeneration at the posterior pole. Left eye examination showed normal findings. Roentgenogram showed enlarged right orbital cavity with soft tissue mass shadow [Figure 4]. Computed tomography (CT) scans revealed a large 8.0 cm × 4.0 cm cystic well-encapsulated ovoid non-enhancing tumor in the right superior orbit compressing the globe and pushing it downward and outward. A few calcific foci were also noted with no bony erosions [Figure 5] and [Figure 6].
|Figure 4: X-ray skull PA view showing enlarged right orbital cavity with thinned walls and soft-tissue mass|
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|Figure 5: Computed tomography scan showing ovoid well defined cystic mass fi lling the entire orbit with foci of calcification (red arrow)|
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|Figure 6: Computed tomography scan showing luxated globe below the cyst with splinting of the optic nerve at the orbital margin (red arrow)|
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Under general anesthesia, using the combined transperiosteal anterior orbitotomy via infrabrow incision along the orbital rim and Stallard's lateral orbitotomy approach, an ovoid well-encapsulated fluctuant mass located subperiosteally was found separate from other structures. It was easily dissected and excised in toto measuring 8.0 cm × 4.0 cm × 5.0 cm [Figure 7].
|Figure 7: Surgical gross specimen showing smooth surface tumor measuring 8.0 cm × 4.0 cm × 5.0 cm|
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Post-operatively there was a residual ptosis with deep superior sulcus and moderate exotropia in RE [Figure 8]. Visual acuity improved to FC at 5 feet but no further due to compressive optic neuropathy and macular degeneration, although chorioretinal folds disappeared. EOM remarkably improved to near normal with removal of the cosmetic blemish [Figure 9]. Histopathological examination (HPE) showed thickened cyst wall (0.5-1.0 cm), sheets of spindle shaped cells with elongated wavy nuclei, areas of hyalinization with massive cystic degeneration suggestive of Schwannoma [Figure 10]. On follow-up over the next 5 years, the patient was apparently healthy with no evidence of any recurrence.
|Figure 8: Post-operative frontal photograph with exotropia from compressive optic neuropathy|
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|Figure 10: Histopathology showing elongated wavy nuclei with cystic degeneration (H and E, ×225)|
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| Discussion|| |
Schwannoma is an uncommon benign orbital tumor that represents a pure proliferation of schwann's cells in the peripheral nervous system.  These tumors account for approximately 1% of all orbital tumors and are found in 1.5% of patients with neurofibromatosis type 1, however, they may also present in patients without the stigmas of it  as seen in our case.
Schwannomas are seen in young to middle aged adults with no sex predilection.  They have been reported in eyelids,  sclera,  conjunctiva,  uvea  and orbit. , Most orbital tumors appear to originate from divisions of the trigeminal nerve and EOM are generally not affected unless there has been collateral intraoperative damage.  In orbit, it is not easy to identify the particular nerve of origin of tumor because of the anatomy but, is often located in the superior quadrant with associated hypophthalmos. 
Because of the slow growth and resulting quite insidious proptosis, Schwannomas tend to be well- tolerated and painless. The orbital tissues and eyelids tend to accommodate to them with massive overgrowths and hypertrophy.  There is little evidence of congestion and edema of eyelids-conjunctiva and exposure keratopathy. Visual deficit can result from induced hyperopia with retinal striae and compressive optic neuropathy  as noted in our case.
On CT scan, Schwannomas appear as well-circumscribed round to ovoid and sometimes as elongated masses located behind the globe or in any of the orbital quadrants.  The radiographic differential diagnosis of such molded lesions include cavernous hemangioma, fibrous histiocytoma and hemangiopericytoma.  CT scan can help in diagnosis, but can be confirmed only by HPE after excision biopsy.
Surgical approach depends primarily on tumor location. Well-circumscribed, isolated encapsulated Schwannomas aids in complete local excision.  The tumor displays a smooth surface and have translucent fish-flesh to tan coloration. They are fluctuant and friable on palpation; on the cut surface, there may be foci of hemorrhage, yellow discoloration and outright cavity formation. Advanced cyst formation (the so called "ancient Schwannoma") is a rarely reported entity.  Calcified Schwannoma of the orbit is even more rarely reported in the world literature. ,
Microscopically, both solid areas (Antoni A) and more myxoid areas (Antoni B) alternate with each other in varying proportions. Mitoses are absent and nuclear atypism is unusual. The capillaries often show a thickened basement membrane, which can lead to hemorrhagic degeneration and massive cystic degeneration in the core of a Schwannoma. 
Schwannomas are held to be relatively immune to malignant transformation, even on recurrence, which may take many years.  We report a case of orbital Schwannoma proven histologically with massive cystic degeneration and calcification, a rare phenomenon, which presented with complete globe luxation and subperiosteal location. Schwannoma should be included in the differential diagnosis of cystic orbital lesions.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10]