Extradural Lesion, Solid Enhancement

Kevin R. Moore, MD

DIFFERENTIAL DIAGNOSIS

Common

Less Common

Rare but Important

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Use all known clinical information as clues to help narrow the differential possibilities

Helpful Clues for Common Diagnoses

Peridural Fibrosis
- Epidural scar formation after lumbar spinal surgery
- Infiltration of epidural/perineural fat by enhancing soft tissue density (intensity) in correct clinical context
Metastases, Blastic Osseous
- Bone production > bone destruction
- Destroys posterior vertebral body cortex first → pedicle
- Hypointensity reflects blastic changes
Metastases, Lytic Osseous
- Bone destruction > bone production
- Destroys posterior vertebral body cortex first → pedicle
- Lesions diffusely enhance (may mask lesions if no fat suppression used)
Neurofibroma
- Variable involvement of spinal root, neural plexus, peripheral nerve, or end organs
- Plexiform neurofibromas are pathognomonic of NF1, often affect sacral or brachial plexus
Schwannoma
- Neoplasm of Schwann cell investiture of spinal and peripheral nerves
- Peripheral origin pushing adjacent axons rather than infiltration within → distinguishes from neurofibroma
- Consider neurofibromatosis type 2 if many tumors are identified
Lymphoma
- Lymphoreticular neoplasms with wide variety of specific diseases & cellular differentiation
- Multiple types with protean imaging manifestations
Plasmacytoma
- Solitary monoclonal plasma cell tumor of bone or soft tissue
- Often without specific features to distinguish from solitary hematogenous metastasis

Helpful Clues for Less Common Diagnoses

Venous Vascular Malformation
- Congenital transpatial vascular malformation of venous channels present from birth
- Mass-like, frequently enhances moderately (less than soft tissue hemangioma)
- No arterial vessels within lesion
- Venous channels may be large; look for phleboliths to make specific diagnosis
Neuroblastic Tumor
- Neuroblastic tumors = ganglioneuroma, ganglioneuroblastoma, and neuroblastoma
- Abdominal (40% adrenal, 25% paraspinal ganglia) > thoracic (15%) > pelvic (5%) > cervical (3%); miscellaneous (12%)
- Identification of intraspinal spread has important treatment and prognostic implications
  - MR is more sensitive than CT for detecting intraspinal spread
Ewing Sarcoma
- Usually adolescents, younger adults
- Permeative cellular lytic lesion of vertebral body or sacrum
- Involve vertebral body, ribs, ilium before neural arch
Hemangioma
- Typical “benign” (fatty stroma) hemangioma hyperintense on T1WI and T2WI MR + contrast enhancement
- “Aggressive” hemangioma iso- to hypointense on T1WI and hyperintense on T2WI MR + avid contrast enhancement
  - Lesion growth, bone destruction, vertebral collapse, absence of lesion fat, active vascular component
  - Pathologic fracture or epidural extension is common → cord compression