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 Table of Contents  
CASE REPORT
Year : 2022  |  Volume : 2  |  Issue : 4  |  Page : 941-943

Ocular schwannoma masquerading as amelanotic choroidal melanoma: A case report


Department of Ophthalmology, Ocular Pathology, Dr. R. P. Centre for Ophthalmic Sciences, AIIMS, New Delhi, India

Date of Submission04-Mar-2022
Date of Acceptance18-Jul-2022
Date of Web Publication11-Oct-2022

Correspondence Address:
Dr. Navneet Sidhu
Room No 490, Dr. R.P. Center for Ophthalmic Sciences, AIIMS, New Delhi- 110029
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijo.IJO_596_22

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  Abstract 


A 29-year-old male was incidentally diagnosed with amelanotic choroidal melanoma in the nasal quadrant of the right eye following an ocular examination due to accidental entry of an insect in the eye. The patient underwent right eye stereotactic Gamma Knife radiosurgery. The tumor mass showed regression six months after therapy. After 12 months, the patient presented again with diminution of vision with recurrence of choroidal mass and total retinal detachment. He underwent a right eye enucleation. Histopathological examination revealed spindle-shaped cells arranged in fascicles and immune stain positivity for S-100 and negative for HMB-45 and Melan-A—suggestive of schwannoma.

Keywords: Amelanotic choroidal melanoma, enucleation, optic nerve schwannoma, spindle cells, stereotactic gamma knife radiosurgery


How to cite this article:
Sidhu N, Gera A, Lomi N, Sen S. Ocular schwannoma masquerading as amelanotic choroidal melanoma: A case report. Indian J Ophthalmol Case Rep 2022;2:941-3

How to cite this URL:
Sidhu N, Gera A, Lomi N, Sen S. Ocular schwannoma masquerading as amelanotic choroidal melanoma: A case report. Indian J Ophthalmol Case Rep [serial online] 2022 [cited 2022 Dec 3];2:941-3. Available from: https://www.ijoreports.in/text.asp?2022/2/4/941/358177



Schwannoma, also known as neurilemmoma, is an encapsulated benign peripheral nerve sheath tumor that is common in the head and neck region. It usually arises from peripheral tumors but may also arise from the optic nerve sheath, though rarely. It is a proliferation of the Schwann cells. Uveal schwannoma is also called pseudomelanoma because of the difficulty in differentiating it from uveal melanoma.[1]


  Case Report Top


A 29-year-old male presented to our outpatient department with an accidental insect entry in the right eye; visual acuity of both eyes was 20/20. There was no other ocular or systemic complaint. The anterior segment examination was within normal limits. Intraocular pressure in both the eyes was 14 mmHg. However, on fundus examination, incidentally, a yellowish brown choroidal mass was seen in the nasal quadrant of the right eye, abutting the nasal margin of the optic disc [Figure 1]. On B-scan ultrasonography, a dome-shaped, homogeneous mass was seen arising from the choroid, measuring 7.34 mm in apical thickness and 11.84 mm in largest basal diameter with mild-to-moderate internal reflectivity with positive kappa sign [Figure 2]a. MRI brain and orbit revealed a right intraocular mass abutting the optic disc, which was hyperintense on T1-weighted image and hypointense on T2 weighted image. Fundus fluorescein angiography (FFA) and indocyanine green angiography (ICGA) showed a large, homogenous, circular, hypofluorescent area in the nasal retina [Figure 3]. Following the clinical and radiological examination, a diagnosis of right eye choroidal melanoma was made. An 18-FDG-PET CT scan of the whole body was done to rule out any systemic metastasis or secondary tumor that showed a mildly metabolically active intraocular soft tissue density lesion in the right eye in the posteromedial part (SUVmax 1.59)—suggestive of a choroidal melanoma with no sign of metastasis elsewhere.
Figure 1: (a) Optos fundus clinical picture of the right eye showing a choroidal mass nasal to the disc preoperatively. (b) Optos fundus clinical picture of the right eye showing a choroidal mass nasal to the disc six months after stereotactic Gamma Knife radiosurgery. (c) Optos fundus clinical picture of the right eye showing a recurrent choroidal mass with total retinal detachment one year after stereotactic Gamma Knife radiosurgery

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Figure 2: (a) Preoperative USG of dome-shaped, homogeneous choroidal mass with high initial spike with steep fall (kappa sign) and mild-to-moderate amplitude spikes within the mass. (b) USG after one year showing a recurrent choroidal mass that increased in size with an exudative retinal detachment

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Figure 3: (a) Preoperative FFA of right eye showing a choroidal mass nasal to the disc with leak in early phase. (b) Preoperative FFA of the fovea showing normal foveal avascular zone. (c) Preoperative ICG of mass showing blocked chorioretinal vascular circulation. (d) Preoperative ICG of the fovea showing normal retinal circulation

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Subsequently, the patient underwent right eye stereotactic Gamma Knife radiosurgery. The dose given to the tumor was 26 Gy, whereas to the optic nerve a dose of 6.40 Gy. The tumor showed regression pattern with decrease in mass, measuring 6.2 mm in height and 9.9 mm in largest basal diameter six months after the Gamma Knife radiosurgery. The postoperative visual acuity at six months was 20/63 in the right eye and 20/20 in the left eye.

However, after 12 months, the patient further complained of diminution of vision in the right eye with a presenting visual acuity of no perception to light. His intraocular pressure was 21 mmHg in the right eye and 14 mmHg in the left eye. On examination, he had a recurrent choroidal mass lesion in the nasal quadrant, measuring 15.2 mm in height and 15.9 mm in basal diameter with total retinal detachment [Figure 2]b. Repeat 18 FDG-PET CT scan was advised that showed a mildly metabolically active mass in the right eye in the posteromedial part (SUVmax 3.21) with no metastasis elsewhere. His visual evoked response (VER) showed no response in the right eye. Finally, right eye enucleation was done with primary silicon orbital implant.

Histopathological examination revealed the presence of spindle-shaped cells arranged in fascicles with focal cystic changes seen. Immunological stains was positive for S-100 and negative for HMB-45 and Melan-A, CD-34, GFAP, and Ki-67 [Figure 4]. A diagnosis of intraocular schwannoma was made based on these features.
Figure 4: Histopathology (a) 10× Haematoxylin and Eosin (H and E) stain showing presence of spindle-shaped cells arranged in bundles (Antoni A) and loosely arranged cells (Antoni B). (b) 10× immunohistochemistry showing spindle cells positive for S-100

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  Discussion Top


Intraocular schwannoma is a rare tumor that commonly arises from the iris, ciliary body, and the choroid. Intraocular schwannomas are also known to arise from the Schwann cells of the ciliary nerves, which enter the posterior aspect of the sclera.[1] It is an encapsulated non-pigmented neoplasm that rarely becomes malignant. It frequently masquerades as melanoma; so a histopathological diagnosis is often essential.

Choroidal schwannoma can present as different clinical manifestations, such as diminution of vision, leukocoria, floaters, and neovascular glaucoma, or as an incidental finding, as was seen in our case. It has features similar to that of melanoma on ultrasonography, MRI, FFA and ICG; hence, histopathological confirmation is often necessary.[2] Schwannoma is usually associated with a multi-system disorder like neurofibromatosis.[3] However, our patient had no systemic features of neurofibromatosis. Various studies have shown the presentation of an intraocular mass which later turned out to be a schwannoma.[1],[4] On histopathology, schwannoma is composed of spindle cells with long eosinophilic cytoplasmic processes (Antoni A pattern) and is positive for S-100 and Leu-7.[5]

Our patient was asymptomatic and was incidentally diagnosed with an intraocular mass, which clinically appeared to be choroidal melanoma. The patient even underwent a stereotactic Gamma Knife radiosurgery, after which the mass decreased in size with a resolution of the subretinal fluid. However, there was a recurrence after one year with similar features. Since it was a non-seeing eye, the patient was subject to enucleation, and, surprisingly, histopathological examination revealed it to be a schwannoma arising from the optic nerve, which is a rare finding. However, in our case, a definitive diagnosis based on initial history and clinical presentation could not be made since the tumor was non-pigmented, and hence a differentiation between amelanotic melanoma or choroidal schwannoma could not be made.


  Conclusion Top


Schwannoma is a rare, benign proliferation of Schwann cells. Intraocular schwannomas, although rarely occurring from the optic nerve sheath, may be confused for amelanotic melanomas and should always be kept as a differential diagnosis while managing such tumors.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that his name and initials will not be published and due efforts will be made to conceal his identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
You JY, Finger PT, Iacob C, McCormick SA, Milman T. Intraocular schwannoma. Surv Ophthalmol 2013;58:77-85.  Back to cited text no. 1
    
2.
Yu Y, Cheng Y, Wang K, Sun K, Shen D, Liang J. Intraocular schwannoma: A case series of 3 patients. Oncol Lett 2019;17:1274-8.  Back to cited text no. 2
    
3.
Saavedra E, Singh AD, Sears JE, Ratliff NB. Plexiform pigmented schwannoma of the uvea. Surv Ophthalmol 2006;51:162-8.  Back to cited text no. 3
    
4.
Cho YJ, Won JB, Byeon SH, Yang WI, Koh HJ, Kwon OW, et al. A choroidal schwannoma confirmed by surgical excision. Korean J Ophthalmol 2009;23:49-52.  Back to cited text no. 4
    
5.
Shields JA, Font RL, Eagle RC Jr, Shields CL, Gass JD. Melanotic schwannoma of the choroid. Immunohistochemistry and electron microscopic observations. Ophthalmology 1994;101:843-9.  Back to cited text no. 5
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]



 

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