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Optic nerve schwannoma is an extremely rare benign nerve sheath tumor arising from Schwann cells, which typically do not exist along the optic nerve, as the optic nerve is myelinated by oligodendrocytes (CNS) and not Schwann cells (PNS).
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Therefore, true optic nerve schwannomas are exceedingly rare and likely arise from adjacent peripheral nerves near the orbit or optic canal.
| Modality | Imaging features |
|---|---|
| MR | • Well-circumscribed, ovoid or fusiform mass near the optic nerve sheath or orbital apex |
| • T1-weighted: Isointense to muscle | |
| • T2-weighted: Hyperintense | |
| • Post-contrast T1: Heterogeneous or homogeneous enhancement | |
| • Split-fat sign (peripherally displaced orbital fat) | |
| • Optic nerve compression or displacement | |
| • Rarely shows cystic change or hemorrhage | |
| CT | • Soft tissue mass in the orbit, typically non-calcified |
| • May cause remodeling or expansion of adjacent bony optic canal | |
| • No bony destruction (helps differentiate from malignancy) |
Schwannoma of the optic nerve. MRI of a 36-year-old female presenting with a large retrobulbar tumor and exophthalmos. The tumor is hypointense on T1-weighted (A), hyperintense on T2-weighted sequences (B), and shows avid contrast enhancement of its solid parts (C). Note the cystic degeneration of the tumor. The tumor was surgically removed, and pathology revealed a schwannoma.
Vogele D, Sollmann N, Beck A, Haggenmüller B, Schmidt SA, Schmitz B, Kapapa T, Ozpeynirci Y, Beer M, Kloth C. Orbital Tumors—Clinical, Radiologic and Histopathologic Correlation. Diagnostics. 2022; 12(10):2376. https://doi.org/10.3390/diagnostics12102376