Malignant Optic Nerve Sheath Tumors (MONSTs) are rare and aggressive malignant neoplasms that occur within the optic nerve sheath, which surrounds and protects the optic nerve. These tumors arise from Schwann cells, fibroblasts, or melanocytes within the sheath.
MONSTs typically develop unilaterally, affecting only one eye, although they can also occur bilaterally in some rare instances. They are considered to be a subset of malignant peripheral nerve sheath tumors. MONSTs can affect individuals of any age, although they are more commonly seen in adults.
Clinically, the symptoms of MONSTs can vary depending on the tumor's size and location within the optic nerve sheath. Common presentation includes painless progressive visual loss, proptosis (bulging of the eye), visual field defects, color vision impairment, optic disc swelling, and optic atrophy. In rare cases, MONSTs may also present with pain due to compression or invasion of nearby structures.
Diagnosing MONSTs typically involves a thorough ophthalmological examination, such as fundoscopy and visual field testing. Imaging studies, such as magnetic resonance imaging (MRI) or computed tomography (CT) scans, are also commonly used to assess the extent and characteristics of the tumor.
Treatment of MONSTs usually involves a combination of surgery, radiation therapy, and chemotherapy. Surgical resection is attempted whenever feasible, followed by radiation therapy to minimize the risk of recurrence. However, complete resection may not always be possible, especially in advanced cases. Prognosis is generally poor, with a high rate of local recurrence and distant metastases. Early diagnosis and intervention are crucial in improving outcomes for patients with MONSTs.
