Myxopapillary ependymoma
Core idea
- Slow-growing ependymal tumour from the filum terminale, usually intradural extramedullary in the lumbosacral canal, with myxoid stroma and non-trivial risk of CSF seeding.
Demographics & location
- Age: adolescents–young adults (but can be paediatric).
- Slight male predominance.
- Classic: conus / filum terminale / cauda equina (L2–S2).
- Rare ectopic sites: thoracic spine, intracranial (sacral/coccygeal remnants).
Imaging - MRI
Typical spinal MRI pattern
- Central intradural extramedullary mass, “sausage-shaped” along filum.
- May span multiple vertebral levels.
- Often causes expansion of canal + posterior vertebral body scalloping.
- Location: Intradural extramedullary, central, attached to filum (vs eccentric nerve root mass).
- Signal
- T1: iso–hypointense; hyperintense to cord
- patchy T1-bright mucin/haemorrhage.
- T2: hyperintense, heterogeneous; cysts/septa possible.
- Hypointensity at tumor margin = hemosiderin
- GRE/SWI: peripheral low-signal “cap sign” (haemosiderin).
- T1: iso–hypointense; hyperintense to cord
- Post-contrast
- Strong, often homogeneous enhancement ± small cystic areas.
- Secondary features
- Canal widening, remodelling/scalloping.
- Drop metastases along neuraxis in more aggressive/relapsed cases.
Key differentials
Think “central filum vs eccentric nerve root”
- Conventional conus ependymoma: intramedullary, cord expansion, less clearly extramedullary.
- Schwannoma / neurofibroma: usually eccentric, dumb-bell through foramen, ± target sign, less typical cap sign.
- Filum paraganglioma (cauda equina neuroendocrine tumor)*: similar level but very vascular – flow voids + “salt-and-pepper” appearance.
- Meningioma (lumbar rare): dural-based, dural tail, older female, thoracic > lumbar.
- Intradural metastases
Classic vignette
- Young adult male with long-standing low back pain, radiculopathy.
- MRI: enhancing sausage-like intradural extramedullary mass at L2–L4, central, with cap sign.
