Case of the Week
Section Editors: Sapna Rawal,1 Matylda Machnowska,1 Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2University of Calgary, Calgary, Alberta, Canada
April 1, 2021
Spinal Epidermoid Cyst Post–Myelomeningocele Repair
- Background:
- Spinal epidermoid cysts are rare, comprising less than 1% of tumors involving the spine, and are most frequently seen in the lumbosacral spine. Forty percent are intramedullary and sixty percent are extramedullary.
- Epidermoid cysts arise from pathologic displacement of epidermal cells into the spinal canal. Therefore, they can be acquired from trauma, lumbar puncture, or surgery such as myelomeningocele closure, with implantation of viable epidermal elements, or arise as congenital lesions, particularly when there is improper closure of the neural tube, resulting in the inclusion of epiblasts in the neural tube.
- Clinical Presentation:
- Most commonly asymptomatic
- May have slowly progressive, compressive radiculopathy
- Other signs can be infectious meningitis or chemical meningitis secondary to rupture.
- Key Diagnostic Features:
- Epidermoid cysts are lesions with attenuation and signal similar to CSF.
- On MRI, epidermoid cysts may be mildly hyperintense to CSF on T1WI and FLAIR imaging, reflecting protein or cellular debris.
- DWI shows diffusion restriction.
- Postcontrast, they can have minimal rim enhancement, but when infected may enhance avidly.
- Differential Diagnoses:
- The top differential diagnosis of an epidermoid cyst includes a spinal arachnoid cyst, dermoid cyst, and neurenteric cyst. Diffusion restriction is the best way of distinguishing an epidermoid cyst from these cysts.
- Spinal arachnoid cyst: Follows CSF signal intensity on all sequences without restricted diffusion
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Dermoid cyst: Unlike epidermoid cysts, it contains skin appendages (hair follicles, sweat glands, sebaceous glands). T1WI is variable because of the variable contents of the dermoid cyst. It may be hyperintense to CSF on FLAIR and on DWI is less likely to show diffusion restriction than epidermoid cysts.
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Neurenteric cyst: Intradural cyst that usually is ventral to the cord, may have associated vertebral anomalies, and is hyperintense to CSF on T1WI with proteinaceous content
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Cystic neoplasms: Spinal cystic schwannomas are benign tumors arising from the spinal nerve root sheaths. Cystic schwannomas are less common than solid lesions. These tend to be hypointense on T1WI and hyperintense on T2WI, with rim enhancement.
- Treatment:
- Complete surgical excision because symptoms may slowly progress if untreated
- Usually has a good neurologic prognosis
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