1. Imaging Findings of Extraosseous Chordomas Arising from the Cervical Spinal Region
A Neuroradiologic Review
R J McDonald MD PhD, C Inwards MD, J M Morris MD
ASNR 2015
Chicago, IL

2. Outline
1. Embryologic Overview 2. Anatomic Overview 3. Pathologic Overview 4. Imaging Features of Extraosseous Chordomas 5. Differential Diagnosis 6. Biopsy Considerations 7. Conclusions

3. Embryologic Overview
Notochord development
Notochord arises from mesoderm spanning the length of the embryo
Ectoderm forms a groove parallel to the notochord dorsally
Neural tube forms from groove which gives rise to spinal cord and brain
Notochord remnants in adult humans spans the primitive axis (red dashed line) and normally gives rise to the nucleus pulposus of the intervertebral discs. Chordomas can arise anywhere along the primitive notochord tract.

4. Anatomic Overview Spheno-Occipital (35%) Spine (15%)
Most commonly arises from clivus
Sites of Chordoma Occurrences
Spine (15%)
Least common location
Sacro-Coccygeal (50%)
Most common primary malignant sacral tumor

5. Pathologic Overview
Cytokeratin AE1/AE3
40x
H&E
40x
100x
S-100
40x
Brachyury
40x
H&E Stain: Bubbly appearance (vacuoles) of cords and lobules of physaliferous cells separated by fibrous septa and myxoid stroma
Immunohistochemistry: Positive for the structural protein cytokeratin (+++), calcium binding protein S-100 (++), and the conserved transcription factor brachyury (+) responsible for defining the midline of all bilaterian organisms

6. Case 1: 12 F w/ biopsy proven chordoma at C1-C2
T1 : Hypo to isointense
T2 : Markedly hyperintense
Gad : Hetero enhancement
Imaging Pearls
Lobulated/septated on T2
Markedly T2 hyperintense
Anterior to vertebral artery
Hypoattenuating to soft tissue
Erosive bony remodeling *
CT : Erosive remodeling
(Aggressive)
CT : Hypodense

7. Case 2: 47 M w/ biopsy proven chordoma at C5
T1 : Hypo to Isointense
T2 : Markedly hyperintense
(Encasing vertebral artery)
Gad : Peripheral enhancement
Imaging Pearls
Can encase vertebral artery *
Can invade central canal *
Peripheral enhancement *
Peripheral calcification *
Permeative bone destruction *
* Denotes imaging variant
CT : Hypodense
CT : Permeative changes *

8. Case 3: 43 F w/ biopsy proven chordoma at C4*
T1 : Hypo to Isointense
T2 : Heterogenously hyperintense
(Usually markedly hyperintense)
Gad : Avid heterogenous enhancement
Imaging Pearls
Heterogenous T2 signal *
Mixed osseous and extraosseous origin *
Homogenous enhancement *
Erosive bone destruction
* Denotes imaging variant
CT : Mixed osseous & extraossous origin
CT : Erosive changes

9. Case 4: 52 M w/ recurrent chordoma at C2-C3 interspace s/p resection
T1 : Hypo to Isointense
T2 : Recurrence vs Postop Changes?
Gad : Recurrence vs Postop Changes? *
Imaging Pearls
Incomplete resection  100% chance of slow regrowth.
In the postoperative spine, T2 hyperintensity and enhancement from postoperative change can confound diagnosis of recurrent chordoma.
Collect both axial and sagittal planes to confirm recurrence.
SAG T2 : RECURRENCE!

10. Imaging Overview
T1 Uniformly iso to hypointense relative to soft tissues
T2 Uniformly hyperintense & lobulated/septated appearance Heterogenous appearance is a less common variant
Gad Uniformly heterogeneous appearance is most common
Peripheral enhancement is a less common pattern
CT Erosive and/or permeative patterns of bone destruction
Other The extent of osseous involvement can vary
CT and MRI are complementary exams for chordomas

11. Differential Diagnosis
Schwannoma – Most common/likely extraosseous extradural spinal lesion.
When approaching a case, one should ask “why is this not a schwannoma?”
Chondrosarcoma – Rare but can be extraosseous and mimic chordoma
Chordoma – Rare (in the spine) and are a mimic of schwannoma
Lymphoma – Appearance can vary but can mimic schwannoma and chordoma
Meningioma – Extradural component can mimic schwannoma and chrodoma

12. Schwannoma vs Chordoma
Imaging Discriminators
Benign bone remodeling Chordoma is erosive/destructive
Behind vertebral artery Chordoma is anterior to or encases it
Dumbell-shaped exiting foramen. Chordoma erodes bone
Can have overlap in T2 and Gad signal/appearance between Schwannoma and Chordoma.
Schwannoma
T2 : Hyperintense and heterogenous
Gad : Avid peripheral
Chordoma
T2 : Hyperintense and homogenous
Gad : Heterogeneous

13. * Chondrosarcoma vs Chordoma Imaging Discriminators
T2 appearance can be similar to chordoma if there is a significant extraosseous component
“Rings and arcs” with expanded matrix on CT can help discriminate
CT complements MRI in these cases.
Chondrosarcoma
T2 : Hyperintense with septation
CT : Arcs and rings *
Chordoma
T2 : Hyperintense with septation
CT : Erosive Destruction

14. Lymphoma vs Chordoma Imaging Discriminators Lymphoma Chordoma
T1 : hypo to isointense
T2 : hypo to isointense
Gad : homogenous
CT : minimal erosion
CT : adenopathy
Chordoma
T1 : hypo to isointense
T2 : hyperintense
Gad : varies
CT : more erosion
Imaging Discriminators
Little to no bony destruction with lymphoma (vs moderate to extensive with chordoma).
T2 hypo to isointense (vs hyperintense) & lacks cystic/lobulated appearance of chordoma.
Homogenous enhancement with lymphoma (chordoma varies but is not as homogenous).
Look for secondary signs of lymphoma on CT (e.g. bulky adenopathy) absent with a chordoma.

15. Meningioma vs Chordoma
Imaging Discriminators
T1 signal intensity is similar between meningioma and chordoma
T2 signal of meningioma is typically less hyperintense
Gad enhancement of meningioma is more homogenous than chordoma
Look for dural tail of meningioma
Meningioma
T1 : hypo to isointense
T2 : iso to mildly hyperintense
Gad : homogenous
Chordoma
T1 : hypo to isointense
T2 : hyperintense
Gad : varies

16. Biopsy Options Biopsy Considerations
Chordomas are slow-growing tumors with a marked propensity for recurrence when residual tissue remains
Percutaneous biopsy will cause seeding of biopsy tract
For this reason, chordomas are resected en bloc and biopsy tracts are also resected
Choose approach carefully to minimize damage to other facial/neck structures due to required resection.

17. Conclusions
Chordomas are benign slow-growing tumors that uncommonly arise from notochord remnants in the spine
Imaging characteristics of chordomas are somewhat nonspecific and can be mistaken for schwannoma, meningioma, or lymphoma. Although rare, chordoma should remain on the differential of any extradural spinal mass.
CT and MRI are complementary methods to help discriminate between these tumors – both should be used when possible.
Due to the propensity for recurrence, particularly along biopsy tracts, and non-specific imaging characteristics, proper biopsy planning is crucial to minimize the risk of seeding/recurrence in the face/neck.