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Show Clinical Observation Optic Nerve Sheath Melanoma Presenting as a Central Retinal Vein Occlusion Alexander Barash, MD, Patrick A. Sibony, MD, Nigel A. Stippa, BS, Nariman S. Boyle, MD, James E. Davis, MD Abstract: A 64-year-old woman, with a history of diabetes and melanoma, developed a central retinal vein occlusion (CRVO) in her left eye. On exam, she had severe disc edema with retinal nerve fiber layer thickening, and anterior deformation of the peripapillary retinal pigment epithelium (RPE)/Bruch membrane layer (ppRPE/BM) toward the vitreous on spectral domain optical coherence tomography (SD-OCT) suggesting an optic nerve sheath (ONS) meningioma. Magnetic resonance imaging findings and ONS biopsy later confirmed a metastatic melanoma. This case demonstrates that the shape of the RPE/BM on SD-OCT may aid in the decision to consider imaging in patients with isolated CRVO. Journal of Neuro-Ophthalmology 2016;36:70-72 doi: 10.1097/WNO.0000000000000310 © 2015 by North American Neuro-Ophthalmology Society M etastatic melanoma to the optic nerve is extremely rare and often misdiagnosed (1). Progressive infiltration of the optic nerve rarely may cause a central retinal vein occlusion (CRVO). Without clinical suspicion, it may be difficult to diagnose the underlying tumor (2). We describe infiltration of the optic nerve sheath (ONS) from metastatic melanoma masquerading initially as a CRVO and later as an ONS meningioma. A novel finding on spectral domain optic coherence tomography (SD-OCT) and distinctive characteristics on magnetic resonance imaging (MRI) helped to guide the workup and establish the clinical diagnosis, which was confirmed Department of Ophthalmology (AB, PS, NB), Pathology (JED), and School of Medicine (NS), State University of New York at Stony Brook, Stony Brook, New York. The authors report no conflicts of interest. Address correspondence to Patrick Sibony, MD, Department of Ophthalmology, Health Sciences Center Level 2-152, Stony Brook University, Stony Brook, NY 11794-8223; E-mail: Patrick.Sibony@ stonybrookmedicine.edu 70 by ONS biopsy. This case illustrated that optical coherence tomography (OCT) may be a critical tool for rethinking the diagnosis of CRVO. CASE REPORT A 64-year-old diabetic woman presented with rapid, painless vision loss in her left eye. Eleven months earlier, she was diagnosed with melanoma on her breast and treated with interferon alpha. She appeared to be in remission. On examination, visual acuity in the left eye was hand motion with a left relative afferent pupillary defect, marked optic disc edema, and intraretinal and nerve fiber hemorrhages throughout the posterior pole (Fig. 1A). Slit-lamp exam, eye movements, and intraocular pressure (IOP) of the left eye were normal. Examination of the right eye was unremarkable. SD-OCT of the left eye showed severe disc edema with retinal nerve fiber layer thickening, and anterior deformation of the peripapillary retinal pigment epithelium (RPE)/Bruch membrane layer (ppRPE/BM) toward the vitreous (Fig. 1B). MRI showed diffuse thickening of the left optic nerve (Fig. 2). There was no calcification of the left optic nerve on computed tomography. An incisional biopsy of the ONS revealed malignant melanoma (Fig. 3). The tumor was found to have a V600E BRAF mutation on molecular testing. After SD-OCT showed a more normal appearance of the RPE/BM layer. The patient was referred to radiation oncology and received localized radiation with Cyberknife for local tumor control. During the planning process, multiple brain metastases were found on repeat MRI, and the patient ultimately underwent whole brain radiation therapy. Six months later, the patient had no vision in her left eye with resolution of retinal hemorrhages and optic atrophy. We subsequently learned that the patient died 1 year after whole brain radiotherapy. Barash et al: J Neuro-Ophthalmol 2016; 36: 70-72 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Clinical Observation FIG. 1. A. Left fundus shows marked optic disc edema with widespread retinal hemorrhages. B. Nine-millimeter spectral domain optic coherence tomography reveals the left optic disc to be elevated with thickened retinal nerve fiber layer. There is inward deformation of the ppRPE/BM layer indenting the globe toward the vitreous (arrows) more evident on the nasal than temporal side. C. Twenty-four hours after ONS biopsy, the RPE/BM layer resumed a more normal contour pointing away from the vitreous. DISCUSSION CRVO is most often associated with hypertension, diabetes, glaucoma, and less commonly with various hematologic and hypercoagulable conditions. It is well known that infiltrating tumors of the optic nerve rarely can cause venous stasis and CRVO (1,3-6). Thus, MRI is rarely included in the workup of a CRVO. The decision to obtain an MRI to rule out an infiltrating optic nerve tumor in our patient was based on a history of a systemic neoplasm and the findings on SD-OCT. Previously, we have shown that the shape of the RPE/BM layer visualized on the raster images of the SD-OCT is displaced anteriorly toward the vitreous in at least 2 settings: intracranial hypertension with papilledema (7) and presumed ONS meningiomas (pONSM) (8). In papilledema with intracranial hypertension, anterior deformation is due to the translaminar pressure gradient between IOP and cerebrospinal fluid pressure (CSF). The mechanism of deformation in pONSM is less clear but probably the result of a decrease in compliance of Barash et al: J Neuro-Ophthalmol 2016; 36: 70-72 FIG. 2. Axial magnetic resonance imaging. A. Precontrast T1 scan shows hyperintense signal along the length of the left optic nerve. B. On T2 sequence, the left optic nerve is diffusely enlarged but isointense with the right optic nerve. C. Postcontrast T1 image reveals marked enhancement of the left optic nerve with flattening of the posterior globe (arrow). the ONS. It has been shown that deformation is not a function of disc edema alone because patients with the same degree of swelling due to nonarteritic anterior ischemic optic neuropathy do not exhibit this deformation; moreover, patients with intracranial hypertension and optic atrophy may also exhibit this deformation (7). That the ppRPE/BM layer contour returned to normal within 24 hours after surgery in our patient (Fig. 2C); in effect, an ONS fenestration suggests a change in ONS compliance (8). However, it is also possible that fenestration released a sequestered pocket of CSF causing localized increased pressure (9). Given the patient's history of malignancy and new onset CRVO, the shape of the RPE/BM seen in the patient's initial OCT of the affected eye raised suspicion for possible 71 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Clinical Observation FIG. 3. Histopathology of left optic nerve sheath biopsy. A. Specimen shows increased cellularity and areas of brown pigment (hematoxylin & eosin, ·4). B. Dual immunohistochemical stain (MART-1/HMB-45) reveals diffuse cytoplasmic immunoreactivity (·4). C. Melanoma cells are present with large, irregular nuclei and granular brown cytoplasmic pigment (hematoxylin & eosin, ·10). D. Dual immunohistochemical stain (MART-1/HMB-45) shows diffuse cytoplasmic immunoreactivity (·40). optic nerve infiltration and an orbital MRI was ordered. It revealed diffuse thickening with enhancement along the entire length of the intraorbital ONS, findings consistent with ONSM. However, the left optic nerve was hyperintense on precontrast T1 images suggesting the presence of blood or melanin. In contrast, ONSM is usually isointense on T1, hyperintense on T2, and enhances with intravenous contrast (10). Dural involvement by malignant melanoma is rare. There are a few reported cases of primary dural malignant melanoma, several cases of malignant melanoma of the meninges in patients with a Nevus of Ota, and reports of primary dural melanoma (10-13). Finally, there are no reported cases of CRVO caused by ONSM, further raising suspicion for metastatic melanoma. STATEMENT OF AUTHORSHIP Category 1: a. Conception and design: P. A. Sibony; b. Acquisition of data: P. A. Sibony and J. E. Davis; c. Analysis and interpretation of data: P. A. Sibony, N. S. Boyle, A. Barash, N. A. Stippa, and J. E. Davis. Category 2: a. Drafting the manuscript: P. A. Sibony, A. Barash, and N. A. Stippa; b. Revising it for intellectual content: P. A. Sibony, A. Barash, J. E. Davis, and N. 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