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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July 25, 2024
Ruptured Spinal Cord Dermoid
- Background:
- Spinal dermoid cysts constitute 1.1% of intraspinal tumors.
- Ectopic ectodermal rests during embryonal neural tube closure give rise to spinal dermoid cysts.
- In rare circumstances, spinal surgery, lumbar puncture, or trauma can cause abnormal dermal seeding, potentially leading to spinal dermoid cysts.
- Spinal dermoid cysts predominantly occur in the lumbosacral canal (60%), followed by thoracic (10%) and cervical canals (5%).
- Approximately 20% of the cases are associated with dermal sinus, spinal dysraphism, and low-set tethered cord.
- Clinical Presentation:
- Remains asymptomatic in most cases; may present with progressive sensorimotor deficits, bowel, or bladder dysfunction
- Patients may present acutely with altered mental status, headaches, and other symptoms related to aseptic chemical meningitis or ventriculitis
- Rupture may happen spontaneously or be associated with surgery and trauma
- Mortality and morbidity increase in case of rupture; hydrocephalus may be short- or long-term sequala of rupture
- Key Diagnostic Features:
- MRI is the most useful modality for early and accurate diagnosis for fat content detection. However, not all dermoid cysts display a high T1 MR signal. Occasionally, dermoid cysts demonstrate heterogeneous signals based on variable contents such as hair, bone, cartilage, or other debris.
- Dermoid cysts may rupture into the cervicothoracic syrinx; this may be seen as multiple, discrete, rounded, or oval hyperintense signals on T1-weighted images.
- Dissemination of high signal T1-weighted lipid discrete or confluent droplets/globules in the syrinx is characteristic of ruptured dermoid cysts.
- CT is a useful adjunct tool to detect bone or calcification, or to diagnose spinal dysraphism. In addition, CT can easily differentiate lipid content from pneumocephalus.
- Differential Diagnosis:
- Spinal epidermoid cyst: cystic tumor lined by squamous epithelium. Unlike dermoid cyst, it doesn’t contain skin appendages (hair follicles, sweat glands, sebaceous glands). Usually extramedullary and isointense to CSF on T1- and T2WI and has restricted diffusion. No enhancement or a thin rim of capsular enhancement.
- Spinal lipoma: typically intradural, subpial, juxtamedullary lesions. Occasionally has been reported as entirely intramedullary lesion. Sharply circumscribed mass. Hyperintense signal in T1- and T2WI with suppression in fat-suppressed sequences. No enhancement.
- Spinal ependymoma: the most common intramedullary neoplasm in adults. Most are isointense to hypointense in T1WI, and hyperintense in T2WI with perilesional cord edema. Associated hemorrhage leads to the “cap sign” (a hypointense hemosiderin rim on T2-weighted images). Virtually all enhance strongly.
- Hematomyelia: may be due to trauma, vascular malformations, intramedullary tumors, radiation therapy, anticoagulant therapy, previous spinal instrumentation due to spinal surgery or lumbar puncture, coagulopathy, or dural arteriovenous fistula. No suppression in fat-supressed sequences.
- Treatment:
- Management depends on the clinical presentation of each case; it must target the underlying mechanism responsible for the patient’s symptoms.
- In patients complaining of cauda equina symptoms, spinal canal decompression with dermoid resection is the treatment of choice.
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