Description
Myxopapillary ependymoma is a distinct subtype of ependymoma characterised by its histological appearance and location. This neoplasm is typically located in the filum terminale and the conus medullaris of the spinal cord, featuring a ‘myxopapillary’ architectural pattern, with myxoid material surrounding vascularised papillary structures.
Pathogenesis
The exact pathogenesis of myxopapillary ependymoma is not fully understood. These tumours are believed to originate from ependymal cells that line the central canal of the spinal cord. The tumours grow slowly, progressively causing compression and displacement of the surrounding nervous tissue, which gives rise to the associated clinical symptoms.
Epidemiology, Risk Factors & Associations
- Most common spinal cord neoplasm in adults (peak incidence: 20-40 years).
- No established risk factors or associations.
Clinical Features
- Characterised by slow progression of symptoms, typically over months to years.
- Common symptoms include lower back pain, sciatica, numbness or weakness in the legs, and bladder or bowel dysfunction.
Complications
- Neurological deficits due to compression of spinal cord.
- Metastases, although rare, can occur via CSF pathways.
Pathological Features
Histopathology
- Macroscopic: Typically well-circumscribed and gelatinous tumours.
- Microscopic: Papillary architecture with myxoid stroma surrounding fibrovascular cores. Ependymal cells surrounding these cores have a cuboidal to columnar shape.
Serology
No specific serological markers.
Biochemistry
No specific biochemical markers.
Radiological Features
General Features
- Well-defined, lobulated mass usually located in the cauda equina or filum terminale.
- Tendency for calcifications and cyst formation.
CT
- Non-contrast: Iso- to hyperdense compared to spinal cord. Calcifications can be observed.
- Contrast-enhanced: Shows strong, homogeneous enhancement.
MRI
- T1WI: Isointense to hypointense compared to spinal cord.
- T2WI: Hyperintense.
- T1 C+: Strong, homogeneous enhancement.
- DWI/ADC: No specific features.
PET FDG
No specific PET features.
Grading and Staging
- Graded as WHO Grade I, indicating a slow-growing, well-differentiated neoplasm.
- No specific staging system due to the rareness of metastases.
Diagnosis
- Diagnosis is usually made based on a combination of clinical, radiological and pathological assessments. The definitive diagnosis requires histopathological confirmation from a biopsy or surgical specimen.
Differential Diagnosis
- Schwannoma: Usually located in the nerve roots of the cauda equina. On MRI, characterised by heterogeneous signal intensity and less pronounced contrast enhancement.
- Meningioma: Predominantly found intradurally and extramedullary, and tends to show ‘dural tail’ sign on contrast-enhanced MRI.
- Metastasis: More common in older adults with known primary malignancies. Typically shows multiple lesions and vertebral body involvement.
Management
- Neurosurgical resection is the treatment of choice.
- Regular follow-up with MRI is recommended to monitor for recurrence.