Intradural/Extramedullary Lesion, Solid Enhancement

Kevin R. Moore, MD

DIFFERENTIAL DIAGNOSIS

Common

Solid Mass
- Schwannoma
- Meningioma
- Neurofibroma
- Ependymoma, Myxopapillary, Spinal Cord
Leptomeningeal
- Metastases, CSF Disseminated
- Post Chemo/Radiation Therapy Nerve Enhancement

Less Common

Rare but Important

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Distinguishing between nodular and smooth linear enhancement helps to narrow the differential diagnosis list

Helpful Clues for Common Diagnoses

Schwannoma
- Well-circumscribed, dumbbell-shaped enhancing mass
- Most commonly solitary; multiple small schwannomas studding leptomeningeal surface ⇒ neurofibromatosis type 2
Meningioma
- Slow growing, benign enhancing intradural/extramedullary mass + dural “tail”
- 90% intradural (10% extradural/or “dumbbell”)
Neurofibroma
- Localized (90%), diffuse, and plexiform (pathognomonic for NF1) nerve sheath neoplasms
- Multilevel nerve root and paraspinal tumors ⇒ neurofibromatosis type 1
Ependymoma, Myxopapillary, Spinal Cord
- Occurs almost exclusively in conus, filum terminale, cauda equina
- Enhancing cauda equina mass with hemorrhage
- Usually spans 2-4 vertebral segments; may fill entire lumbosacral thecal sac
Metastases, CSF Disseminated
- Spread of malignant tumors through the subarachnoid space
- Smooth/nodular enhancement distributed on cord surface and nerve roots
Post Chemo/Radiation Therapy Nerve Enhancement
- Nonspecific smooth (not nodular) enhancement of intradural nerve roots ± conus pia
- May persist after therapy completed, but should gradually return to normal signal on follow-up studies

Helpful Clues for Less Common Diagnoses

Leukemia
- Abnormal enhancement of leptomeninges on CECT and MR
- Look for diffuse osteopenia, multiple vertebral fractures ± lytic spine lesions to suggest diagnosis
Lymphoma
- Protean imaging manifestations; nodular leptomeningeal metastases rare
Guillain-Barré Syndrome
- Autoimmune post-infectious or post-vaccinial acute inflammatory demyelination of peripheral nerves, nerve roots, cranial nerves
- Smooth pial enhancement of the cauda equina and conus
Meningitis, Spinal
- Infection of spinal cord leptomeninges and subarachnoid space
- Smooth or irregular meningeal enhancement ± CSF enhancement, abnormal CSF signal intensity (“dirty CSF”)
Sarcoidosis
- Combination of leptomeningeal and peripheral intramedullary mass-like enhancement
- Invariable presence of systemic disease helps make diagnosis and avoid biopsy