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Optic nerve neoplasms are tumors often found posterior to the eye. A neoplasm is synonymous with tumor, or an abnormal cellular proliferation. This article will discuss primary eye neoplasms. Secondary eye neoplasms originating in the forebrain can occur, but do not originate in the eye. Rarely, eye tumors such as choroidal melanoma can extend into the optic nerve as well. The types of primary optic nerve cancers are glioma, meningioma and melanocytoma. These neoplasms fit within the larger scope of intracranial tumors.
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Frequency and Pathophysiology
Gliomas, melanocytomas and meningiomas refer to the type of cells from which the optic nerve neoplasm is derived. The suffix -oma refers to tumor.
The process of origination for optic nerve tumors can be spontaneous or predicted. Patients with neurofibromatosis 1 have a predilection towards glioma. The focal origin of optic nerve neoplasms are cap cells derived from the the lining of the brain. A less frequent area of origin is the actual optic nerve sheath. Gliomas commonly progress during childhood and have a good prognosis. They also have hereditary influences.
Meningiomas are rare, with an occurrence rate of 2.3 incidents per 100,000 individuals. They have an unknown cause and occurrences increase with age. They occur at a 2:1 ratio for women:men.
Occurrence for melanocytomas are not well-defined in literature. These tumors have no symptoms in the majority of cases, and have a tendency to be benign. This disease occurs more often in Caucasians.
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Optic Nerve Glioma and Optic Nerve Meningioma share symptomatology:
- Eye bulging
- Eyelid drooping
- Loss of vision
- Double vision
The illness can be asymptomatic as well, despite large lesions found in MRIs. Optic nerve melanocytoma is strongly asymptomatic, but may present with a decreased visual field or partial vision loss.
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The gold standard for diagnosing optic nerve neoplasms is currently MRI or CT scan without contrast. The intensities and calcifications seen on the diagnostic images are consistent with other body tumors. Cerebral angiography (view of vessels) may also be used in diagnosis. In lesions too small to be discerned, or in gross eye protrusion, an eye exam can help determine abnormal growths. Enlarged vessels and discoloration can signify invasion of the tumor into the eye itself. If cancer is suspected, biopsy should be preformed to review the histology for cancer staging.
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Optic nerve melanocytoma is usually left untreated. There is some question if immunosuppressive therapy should be completed, or if the problem should be left alone. Currently no proven treatment exists.
Optic nerve glioma and optic nerve meningioma can be fatal, so radical treatment can be recommended depending on growth severity. Surgical excision of the optic nerve is sometimes recommended. Current protocols can also include radiation and chemotherapy. If the severity of the cancer is small, or the tumor is benign, then a wait-and-see approach may be offered.
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Prognosis varies widely based on cancer staging. Juveniles fare better, but the proximity of the tumor to the brain can cause deep concern. Data exists for optic nerve meningioma. The five-year survival rate for this pathology is 87%.
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Gossman, Mitchell. "Meningioma, Optic Nerve Sheath." Meningioma, Optic Nerve Sheath. Emedicine. Web. 10 Jan. 2011. <http://emedicine.medscape.com/article/1217466-overview>.
"Optic Nerve Melanocytoma - The Eye Cancer Network." Welcome to the Eye Cancer Network: Eye Tumor Information, Doctors and Links. Web. 11 Jan. 2011. <http://www.eyecancer.com/patient/Condition.aspx?nID=64&Category=Optic Nerve Tumors&Condition=Optic Nerve Melanocytoma>.
"Optic Glioma: MedlinePlus Medical Encyclopedia." National Library of Medicine - National Institutes of Health. Web. 11 Jan. 2011. <http://www.nlm.nih.gov/medlineplus/ency/article/001024.htm>.
"Tumors of the Optic Nerve Initiative." University of Iowa. 10 Jan. 2011. Web. <http://webeye.ophth.uiowa.edu/TONI/FAQ.htm>.