Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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November 1, 2018
Schwannoma mimicking MPE
- Background
- WHO Grade 1 tumor arising from the nerve sheath (Schwann cells), which is the most common intradural extramedullary spinal tumor. May also have extradural extension or occur primarily extradural in approximately 15-30% of cases.
- Occurs most commonly in the cervical and lumbar spine, followed by the thoracic spine.
- Solitary lesion in 90% of cases, unless associated with neurofibromatosis type 2 or schwannomatosis, in which multiple schwannomas are characteristic.
- Clinical Presentation
- Localized pain, paresthesia, numbness, and/or motor weakness are typical presentations secondary to compression of the spinal cord or roots.
- Key Diagnostic Features
- Intradural mass classically presenting as a dumbbell shape within the neural foramina with low-to-intermediate T1 and heterogeneously hyperintense T2 signal intensity with homogeneous or heterogeneous enhancement patterns.
- Focal T2 hyperintensities, reflecting cystic degeneration can occur in up to 40% of people. However, predominately cystic schwannomas are rare.
- Frequently associated with hemorrhage, fatty degeneration, and intrinsic vascular changes such as thrombosis and sinusoidal dilation.
- Can demonstrate expansion of bony foramina without direct invasion to adjacent structures.
- Differential Diagnosis
- Myxopapillary ependymoma (MPE): Conus medullaris is a classic location; however, given lateral displacement of the spinal cord, schwannoma was favored and pathology proven in this case.
- Neurofibroma: Neurofribomas arise within the nerve as opposed to schwannoma, which will displace the nerve to the periphery; however, they are extremely difficult to distinguish with imaging. Hemorrhage, cysts, or fat are more common with schwannoma.
- Meningioma: A dural-based mass extramedullary lesion that will typically demonstrate calcification, which is rare in schwannoma.
- Treatment
- Total surgical excision with high success of separation from parent nerve with rare recurrence.
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