Choroidal schwannoma presenting with neovascular glaucoma: A report of two cases.

Schwannoma is a rare benign tumor, which is more commonly found elsewhere in the body along myelin-producing peripheral nerves and is rarely reported within the eye. In this report, we describe two adult patients presenting with a choroidal mass lesion and neovascular glaucoma who underwent enucleation with clinical differential diagnoses of choroidal melanoma and choroidal hemangioma. Histopathology confirmed the diagnosis of choroidal schwannoma. This case series highlights the variable presentation of intraocular schwannoma and how they masquerade as other choroidal tumors.

Introduction

Choroidal schwannoma frequently misleads the clinician to a more ominous diagnosis of amelanotic melanoma owing to its clinical resemblance and sometimes may be misdiagnosed with choroidal hemangioma or leiomyoma. Schwannomas are benign encapsulated tumors, more common in orbit than intraocular when presented in ophthalmic practice and contribute to 1% of all orbital tumors.[1] Intraocular schwannoma is relatively rare with around 50 cases published worldwide. Callender and Thigpen first described intraocular schwannoma in 1930. Intraocularly, they presumably arise from the nerve sheaths of ciliary nerves and are reported more commonly in the choroid and ciliary body than iris.[12] Herein, we report a case series of two patients diagnosed with choroidal schwannoma based on histopathology.

Case Reports

Case 1

A 56-year-old male presented with a history of diminution of vision in the right eye for 10 years and a recent onset of pain and congestion for 3 months. He was on anti-glaucoma medications for raised intraocular pressure (IOP) in the right eye. He denied perception of light in the right eye and had a vision of 20/25 in the left eye. On examination, the conjunctiva of the right eye was congested with an intercalary staphyloma extending from 1 to 3'o clock [Figure 1]. The IOP was 36 mm Hg in the right eye and 14 mm Hg in the left eye. Anterior and posterior segment examination of the left eye was unremarkable. Anterior segment examination of the right eye revealed diffuse corneal stromal edema, diffuse neovascularization of the iris, subtotal hyphema, relative afferent pupillary defect, and posterior subcapsular cataract. A hazy cornea with dense posterior capsular opacity precluded fundus examination. B-Scan ultrasonography revealed a 4.5 mm × 4.5 mm × 6 mm mass with moderate-to-high surface echogenicity and internal echoes with surrounding retinal detachment. Differential diagnoses of the right eye choroidal hemangioma and malignant melanoma were considered. Due to inconclusive diagnoses and presentation with a painful blind eye, the patient underwent enucleation of the right eye.

Figure 1

Description of case 1, (a) A 56-year-old patient presented with corneal edema, hyphema, neovascular glaucoma, and intercalary staphyloma, (b) B-scan ultrasonography showing a well-defined choroidal mass, (c) Whole-mount photograph and (d) light photomicrograph (H and E) of the enucleated globe showing well-circumscribed choroidal tumor, (e) The tumor showing areas of hypercellular Antoni A and hypocellular Antoni B pattern) (H and E, ×10), (f) immunohistochemistry with S-100 showing strong positivity (×10), (g) HMB-45 and (h) Melan A showing poor stain uptake

On gross examination, a grayish-white nodule with circumscribed margins was noted in the choroid with surrounding detached retina. An area of scleral thinning was noted from 1 to 3'o clock. Microscopically, a circumscribed nodule with spindle cells loosely packed in short fascicles with collagenous stroma was noted. The cells had vesicular nuclei with small nucleoli and mild anisonucleosis. There was no evidence of necrosis or mitotic figures. Immunohistochemistry (IHC) with S-100 was strongly positive while being negative for HMB-45 and Melan-A. MIB-1 index was <1%. Based on the histopathology features and IHC, a diagnosis of choroidal schwannoma was confirmed.

Case 2

A 33-year-old female presented with a history of diminution of vision for 2 years. On examination, the visual acuity in the right eye was counting fingers at 2 m, and 20/20 in the left eye. The anterior segment examination of both eyes was unremarkable. Posterior segment examination of the left eye was normal. On dilated fundus examination of the right eye, an amelanotic choroidal tumor measuring 8.5 mm × 9 mm was noted adjacent to the optic disc in the macular region with surrounding subretinal hard exudates and hemorrhages. Ultrasonography revealed a dome-shaped lesion with moderate internal reflectivity. Based on the clinical findings, a clinical diagnosis of choroidal hemangioma was made. The poor visual potential in the right eye was explained to the patient and treatment options of observation versus plaque radiotherapy were discussed. In view of poor visual prognosis with treatment and benign nature of the tumor, the patient did not want any intervention and thus opted for observation. The patient presented 2 years later with a rise in intraocular pressure and neovascular glaucoma. A differential diagnosis of amelanotic melanoma was then considered and enucleation of the right eye was performed.

On gross examination [Figure 2], a grayish white nonpigmented mushroom shaped mass measuring 10 mm × 6 mm was noted in the peripapillary region. Microscopically, a cellular circumscribed lesion with variable cellularity was seen in the posterior pole over the optic nerve head. Cellular areas comprised spindle cells in bundles and fascicles with oval to elongated nuclei. Focal areas of nuclear palisading (Antoni A) with verrocay bodies alternating with few hypocellular areas (Antoni B) with foamy cells and blood vessels were seen. IHC with S-100 was strongly positive, Glial fibrillary acid protein (GFAP) showed poor uptake, and melan-A and HMB-45 were negative. Based on these findings, a final diagnosis of choroidal schwannoma was made.

Figure 2

Histopathology of case 2, (a) Light photomicrograph showing the whole mount of the enucleated eyeball of a 33-year-old patient who presented with neovascular glaucoma and a circumscribed mass abutting the optic disc and arising from the choroid measuring 10 mm × 6 mm (H and E). (b) Tumor showing alternating areas of hypercellularity (Antoni A, white arrow) and hypocellularity (Antoni B, black arrow) (H and E, ×10). (c) Immunohistochemistry with S-100 showing strong positivity and (d) Glial fibrillary acid protein showing poor uptake (×10)

Discussion

Intraocular schwannomas are benign tumors arising from Schwann cells and may be misdiagnosed as choroidal hemangioma[2] or and amelanotic choroidal melanoma. Choroidal hemangiomas are orangish-red and ultrasonography reveals an acoustically dense dome-shaped lesion with high surface reflectivity and moderate-to-high internal reflectivity. Fundus fluorescein angiography reveals hyperfluorescence and indocyanine green angiography reveals early hyperfluorescence and late washout phenomenon. Amelanotic choroidal melanoma appears as a yellowish lesion and ultrasonography reveal a dome-shaped or mushroom-shaped lesion with acoustic hollowness at the base. Scan ultrasonography shows high surface reflectivity and medium-to-low internal reflectivity. Fundus fluorescein angiography reveals hyperfluorescence with dual circulation and indocyanine green angiography reveals hyperfluorescence and delayed staining. Intraocular schwannomas can present as an isolated lesion or can be associated with neurofibromatosis in 8.5% of the cases.[2] They are commonly found in adult females with an average of 37 years of age (range 6 months–76 years).[23] Fundus examination reveals an amelanotic yellowish-white lesion with associated subretinal fluid with/without subretinal exudation, and thus can simulate amelanotic choroidal melanoma. Ultrasonography may not be useful in accurately distinguishing choroidal schwannoma from melanoma due to similar features of high surface reflectivity with low-to-moderate internal echoes in both. Fluorescein angiography can simulate a choroidal hemangioma with initial filling in the choroidal and arterial phases and increased staining with bright hyperflourescence in the late stages. However, indocyanine green angiography of choroidal schwannoma differs from hemangioma with the absence of late wash-out phenomenon. A definitive clinical diagnosis of choroidal schwannoma was not done in both the cases in our series and most of the eyes reported till date were enucleated in view of diagnostic dilemma. A transscleral biopsy may be useful in confirming the diagnosis. However, in our cases, enucleation was done in both cases owing to the late presentation with painful blind eye and neovascular glaucoma. Presentation of choroidal schwannoma with neovascular glaucoma is rare and has not been reported in the literature.

Pathologically, schwannomas have spindle cells with bland nuclei arranged in alternating Antoni A (hypercellular areas with nuclear palisading) and Antoni B (less widely dispersed hypocellular areas in myxoid matrix) patterns with hyalinized vasculature as noted in our patients. Immunohistochemical markers can differentiate schwannomas from melanoma with S-100 being strongly positive, GFAP showing poor uptake in schwannomas while melanocytic markers such as melan-A and HMB-45 are negative in schwannomas except in pigmented variants.[45]

The management options for intraocular schwannomas include transscleral resection and photodynamic therapy.[67] Schwannomas can be observed without any intervention owing to their benign nature and slow growth. Treatment with anti-vascular endothelial growth factor may be useful to treat the surrounding exudation secondary to the high vascular nature of intraocular schwannomas.[8] However, a definitive diagnosis of choroidal schwannoma by clinical examination is rare and is most often diagnosed on the enucleated eye as in our case series.

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

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Conflicts of interest

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