PRIMARY BONE TUMORS OF THE SPINE
Chordoma | Chondrosarcoma | Osteosarcoma | Ewing Sarcoma
ENNEKING STAGING (MUSCULOSKELETAL TUMORS)
Critical Must-Knows
- Chordoma - most common primary malignant spine tumor, arises from notochord remnants, sacrum 50%, skull base 35%
- Chondrosarcoma - second most common, arises from cartilage, ring-and-arc calcifications on CT
- En bloc resection is goal for chordoma/chondrosarcoma (chemotherapy and radiation resistant)
- Ewing sarcoma - pediatric/young adult, highly chemo/radiosensitive, permeative bone destruction
- Osteosarcoma - rare in spine, requires neoadjuvant chemo, osteoid matrix on imaging
Examiner's Pearls
- "Chordoma - T2 hyperintense, physaliferous cells (vacuolated), brachyury positive
- "Chondrosarcoma - ring-and-arc calcifications, arises from posterior elements
- "Marginal excision = 50-70% local recurrence vs 20% with wide margins
- "Ewing and osteosarcoma require chemotherapy unlike chordoma/chondrosarcoma
Critical Primary Spine Tumor Exam Points
Chordoma Location
Know the distribution: Sacrococcygeal 50%, skull base (clivus) 35%, mobile spine 15%. In mobile spine, cervical is more common than thoracic/lumbar. Arises from notochord remnants along the neuraxis.
En Bloc Resection
Surgical margin is key - chordoma and chondrosarcoma are resistant to chemotherapy and conventional radiation. Wide en bloc resection (Enneking) is the only chance for cure. Intralesional = 100% recurrence.
Ewing Sarcoma
Different from chordoma - highly chemosensitive and radiosensitive. Treatment is chemotherapy + surgery or radiation. Peak age 10-25 years. Permeative destruction with soft tissue mass. t(11;22) translocation.
Imaging Features
Know distinguishing features: Chordoma = T2 hyperintense, lobulated, midline. Chondrosarcoma = ring-and-arc calcifications. Osteosarcoma = osteoid matrix, sunburst pattern. Ewing = permeative lytic.
Primary Malignant Spine Tumors - Comparison
| Feature | Chordoma | Chondrosarcoma | Osteosarcoma | Ewing Sarcoma |
|---|---|---|---|---|
| Age at presentation | 40-70 years | 30-70 years | 10-30 years | 10-25 years |
| Location | Midline, sacrum 50% | Posterior elements | Variable | Any location |
| Cell of origin | Notochord remnant | Cartilage | Osteoblast | Neural crest |
| Imaging hallmark | T2 hyperintense | Ring-arc calcification | Osteoid matrix | Permeative lytic |
| Chemo/RT sensitive | No/Minimal | No | Yes (chemo) | Yes (both) |
| Primary treatment | Wide en bloc | Wide en bloc | Neoadjuvant chemo + surgery | Chemo + surgery/RT |
At a Glance
Primary bone tumors of the spine represent only 5% of all spine tumors but require distinct management from metastases. Chordoma is the most common primary malignant spine tumor, arising from notochord remnants with 50% in the sacrococcygeal region—characterized by physaliferous cells, brachyury positivity, and T2 hyperintensity on MRI. Chondrosarcoma shows ring-and-arc calcifications and arises from posterior elements. Both chordoma and chondrosarcoma are resistant to chemotherapy and radiation, making en bloc resection with wide margins the only curative option—marginal excision results in 50-70% local recurrence. In contrast, Ewing sarcoma (pediatric, t(11;22) translocation) is highly chemosensitive and radiosensitive.
Primary Spine Tumors - CEOS
Memory Hook:CEOS tumors - Chordoma and Chondrosarcoma need En bloc, Others (Ewing, Osteo) Sensitive to chemo
Chordoma Key Features
Memory Hook:PBSTN - Physaliferous cells with Brachyury positivity in Sacral tumors that are T2 bright from Notochord
Enneking Staging System
Memory Hook:I-II-III: Low-High-Mets. Stage IIB is most common surgical presentation
Overview and Epidemiology
Primary malignant bone tumors of the spine are rare, accounting for only 5% of all spinal tumors. The most common types are chordoma, chondrosarcoma, osteosarcoma, and Ewing sarcoma.
Relative Incidence of Primary Spine Tumors:
| Tumor Type | % of Primary Spine Tumors | Typical Age | Gender |
|---|---|---|---|
| Chordoma | 40% | 40-70 years | M more than F (2:1) |
| Chondrosarcoma | 20% | 30-70 years | M=F |
| Osteosarcoma | 10% | 10-30 years | M more than F |
| Ewing Sarcoma | 5% | 10-25 years | M more than F |
| Others | 25% | Variable | Variable |
Key Epidemiological Points:
Chordoma and chondrosarcoma are tumors of adulthood, while Ewing sarcoma and osteosarcoma predominantly affect children and young adults. Understanding age at presentation helps narrow the differential diagnosis.
Location Matters
Primary spine tumors have characteristic locations: Chordoma = midline (sacrum, clivus, vertebral body). Chondrosarcoma = posterior elements. Ewing sarcoma = any location. Osteosarcoma = vertebral body or posterior elements.
Pathophysiology
Cellular Origins
Notochordal Origin
Chordoma arises from remnants of the embryonic notochord - the primordial axial skeleton that guides vertebral development.
Pathological Features:
- Physaliferous cells - vacuolated cells containing mucin (pathognomonic)
- Lobulated architecture with fibrous septae
- Abundant myxoid matrix
Immunohistochemistry:
- Brachyury positive (highly specific diagnostic marker)
- Cytokeratin positive (EMA, CK8/18)
- S-100 positive
Three histological subtypes: conventional (most common), chondroid (better prognosis), and dedifferentiated (worst prognosis with high-grade sarcomatous component).
Classification and Staging
Enneking Surgical Staging System
Standard staging for musculoskeletal tumors.
| Stage | Grade | Compartment | Metastases |
|---|---|---|---|
| IA | Low (G1) | Intracompartmental | M0 |
| IB | Low (G1) | Extracompartmental | M0 |
| IIA | High (G2) | Intracompartmental | M0 |
| IIB | High (G2) | Extracompartmental | M0 |
| III | Any | Any | M1 |
Most spine tumors at presentation are Stage IIB (extracompartmental) due to anatomic complexity of spine.
Clinical Presentation
Presenting Symptoms
Pain (Most Common):
- Localized back pain, often insidious onset
- Typically progressive over months
- Night pain and rest pain common
- May be mechanical or constant
Neurological Symptoms:
- Radiculopathy from nerve root compression
- Myelopathy if cord compression
- Cauda equina syndrome with sacral tumors
- Bowel/bladder dysfunction (late)
Tumor-Specific Presentations
Chordoma:
- Sacral: Low back pain, sciatica, constipation, urinary symptoms
- May present with palpable presacral mass on rectal examination
- Skull base: Cranial nerve palsies, headache
Ewing Sarcoma:
- Often presents with systemic symptoms
- Fever, weight loss, elevated inflammatory markers
- May mimic infection
Osteosarcoma:
- Pain and swelling
- Pathological fracture possible
- Elevated alkaline phosphatase
Red Flags
- Pain worse at night or at rest
- Progressive neurological deficit
- Weight loss, fever
- Mass lesion palpable
- Pathological fracture
Investigations
Imaging
Initial Assessment
Often first imaging modality, but sensitivity is limited.
Key Features:
- Lytic vs sclerotic pattern
- Bone destruction
- Matrix mineralization
- Soft tissue mass
Tumor-Specific Findings:
- Chordoma: Midline lytic destruction, soft tissue mass
- Chondrosarcoma: Stippled/ring-arc calcifications
- Osteosarcoma: Dense sclerosis, sunburst periosteal reaction
- Ewing: Permeative/moth-eaten destruction
Plain films may be normal in early disease. Advanced imaging always required.
Biopsy
Principles:
- Biopsy tract must be excisable with definitive surgery
- CT-guided preferred for spine
- Avoid contaminating multiple compartments
- Discuss approach with treating surgeon first
Biopsy Planning Critical
Poorly planned biopsy can compromise subsequent en bloc resection. The biopsy tract will need excision, so coordinate with the surgeon who will perform definitive surgery BEFORE biopsy.
Management
Surgical Principles
Gold Standard for Chordoma/Chondrosarcoma
Goal is negative surgical margins without violating tumor capsule.
Margin Types (Enneking):
- Intralesional: Through tumor (contamination)
- Marginal: Through reactive zone
- Wide: Through normal tissue, cuff around tumor
- Radical: Entire compartment (rarely achievable in spine)
Outcomes by Margin:
- Intralesional: 100% recurrence
- Marginal: 50-70% recurrence
- Wide: 20-30% recurrence
En bloc vertebrectomy is technically demanding and requires experienced spine oncology team.
Treatment Algorithm
Chordoma/Chondrosarcoma:
- Staging (MRI, CT, PET)
- Biopsy (coordinated with surgeon)
- En bloc resection with wide margins
- Consider proton therapy if margins positive
Osteosarcoma:
- Staging
- Neoadjuvant chemotherapy (10-12 weeks)
- Surgical resection
- Adjuvant chemotherapy based on necrosis
Ewing Sarcoma:
- Staging including whole-body PET
- Neoadjuvant chemotherapy
- Surgery or radiation (or both)
- Maintenance chemotherapy
Chemosensitivity Determines Treatment
Chordoma and chondrosarcoma are NOT chemosensitive - surgery is primary treatment. Ewing sarcoma and osteosarcoma ARE chemosensitive - chemotherapy is integral to treatment. This fundamental difference determines management approach.
Complications
Surgical Complications
Early:
- Wound complications (most common, especially sacral)
- Cerebrospinal fluid leak
- Neurological deficit
- Massive blood loss (average 2-5L for sacral tumors)
Late:
- Hardware failure
- Pseudarthrosis
- Adjacent level disease
- Chronic pain
Neurological Deficits
Sacral Resection:
- S1 sacrifice: Ankle plantar flexion weakness
- S2 sacrifice: Bladder/bowel dysfunction likely
- S3 sacrifice: Definite bladder/bowel/sexual dysfunction
Mobile Spine:
- Nerve root sacrifice may be required for clear margins
- Spinal cord injury risk with en bloc techniques
Local Recurrence
Risk Factors:
- Intralesional vs en bloc surgery
- Positive surgical margins
- Tumor grade
- Dedifferentiated histology
Management of Recurrence:
- Re-resection if feasible
- Radiation therapy (proton/carbon ion)
- Palliative care if unresectable
Postoperative Care
En Bloc Spine Tumor Resection Protocol
Postoperative Rehabilitation Timeline
- Intensive care monitoring for first 24-72 hours
- Hemodynamic monitoring (blood loss often 2-5L for sacral resections)
- Drain management and output monitoring
- Pain management (multimodal, patient-controlled analgesia)
- DVT prophylaxis (mechanical initially, chemical once hemostasis assured)
- Wound assessment for flap viability if soft tissue reconstruction
- Mobilisation with physiotherapy (weight-bearing status per surgeon)
- Wound care and drain removal when output minimal
- Bladder/bowel function monitoring (especially sacral resections)
- Nutritional support for wound healing
- Begin rehabilitation for neurological deficits
- Outpatient wound checks every 1-2 weeks
- Progressive mobilisation and physiotherapy
- Brace if spinal instability concern
- Imaging at 6 weeks to assess instrumentation
- Referral for radiation oncology if margins positive (proton therapy)
- Surveillance imaging every 3-6 months (MRI for local, CT chest for metastases)
- Functional rehabilitation for neurological deficits
- Oncology follow-up for adjuvant therapy if indicated
- Psychological support for adaptation to functional deficits
Outcomes
Survival by Tumor Type
| Tumor | 5-Year Survival (Wide Excision) | 5-Year Survival (Marginal/Intralesional) | Key Prognostic Factor |
|---|---|---|---|
| Chordoma | 65-70% | 35-40% | Surgical margin status |
| Chondrosarcoma Grade I | 90% | 70% | Tumor grade |
| Chondrosarcoma Grade III | 30% | 10-15% | Tumor grade |
| Ewing Sarcoma (localized) | 60-70% | Similar (chemo-dependent) | Response to chemotherapy |
| Osteosarcoma | 40-50% | 20-30% | Necrosis rate post-chemo |
Local Recurrence Rates
- Wide margin: 20-30% local recurrence
- Marginal margin: 50-70% local recurrence
- Intralesional: Approaching 100% local recurrence
Margin Status is Key
For chordoma and chondrosarcoma, surgical margin status is the MOST IMPORTANT prognostic factor. En bloc resection with wide margins is the only chance for long-term disease control. Proton beam therapy can help salvage positive margins.
Evidence Base
En Bloc Resection for Chordoma
- 52 patients with chordoma of mobile spine
- Wide en bloc resection: 28% local recurrence
- Intralesional excision: 64% local recurrence
- 5-year survival: 65% with en bloc vs 40% intralesional
Sacral Chordoma Outcomes
- 52 patients with sacral chordoma
- Wide resection: 5-year local recurrence 22%
- Contaminated margins: 5-year recurrence 67%
- Survival correlated with margin status
Spine Ewing Sarcoma
- Multimodality treatment essential
- Chemotherapy + surgery superior to chemo alone
- 5-year survival 50-60% for localized disease
- Local control improves with surgery
Proton Therapy for Chordoma
- Proton therapy improves local control vs photons
- 5-year local control 80-85% with high-dose protons
- Useful for positive margins or unresectable disease
- Carbon ion may provide additional benefit
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Sacral Mass in Adult
"A 55-year-old man presents with 12 months of progressive low back and buttock pain. MRI shows a large destructive sacral mass that is very bright on T2-weighted imaging. The mass extends presacrally."
Posterior Element Tumor with Calcifications
"A 45-year-old woman presents with thoracic back pain. CT shows a mass arising from the posterior elements of T7 with characteristic ring-and-arc calcifications. There is extension into the spinal canal."
Pediatric Patient with Spinal Mass
"A 14-year-old boy presents with 6 weeks of back pain, fever, and weight loss. MRI shows a destructive lumbar vertebral body lesion with large paraspinal soft tissue mass. WCC and ESR are elevated."
Recurrent Sacral Chordoma
"A 60-year-old man who had sacral chordoma resection 3 years ago presents with increasing sacral pain. MRI shows a 4cm presacral mass consistent with local recurrence. There is no distant disease on PET-CT."
PRIMARY BONE TUMORS SPINE
High-Yield Exam Summary
Tumor Types
- •Chordoma: Notochord origin, sacrum 50%, T2 bright, brachyury+
- •Chondrosarcoma: Cartilage origin, posterior elements, ring-arc calcifications
- •Osteosarcoma: Bone-forming, osteoid matrix, sunburst pattern
- •Ewing: Neural crest, pediatric, t(11;22), permeative lytic
Treatment Differences
- •Chordoma/Chondrosarcoma: En bloc resection (chemo/RT resistant)
- •Osteosarcoma: Neoadjuvant chemo + surgery + adjuvant chemo
- •Ewing: Chemo + surgery or radiation + chemo
- •Margin status is critical for chordoma/chondrosarcoma
Enneking Staging
- •Stage I: Low grade (G1), A=intra, B=extra compartmental
- •Stage II: High grade (G2), A=intra, B=extra compartmental
- •Stage III: Any grade with metastases
- •Most spine tumors present as Stage IIB
Surgical Margins
- •Intralesional: Through tumor = 100% recurrence
- •Marginal: Through reactive zone = 50-70% recurrence
- •Wide: Cuff of normal tissue = 20-30% recurrence
- •Radical: Entire compartment (rarely achievable in spine)
Sacral Chordoma
- •Combined anterior-posterior approach
- •Level of resection determines function
- •Above S2-S3: Bladder/bowel dysfunction
- •Preoperative embolization essential
- •Proton therapy if margins positive
Exam Pearls
- •Ring-arc calcification = chondrosarcoma
- •T2 hyperintense sacral mass = chordoma until proven otherwise
- •Pediatric + systemic symptoms + spine mass = Ewing
- •Biopsy tract must be excisable - coordinate with surgeon
MCQ Practice Points
Exam Pearl
Q: What is the most common primary malignant bone tumor of the spine? A: Chordoma. It arises from notochordal remnants and occurs predominantly in the sacrum (50%), skull base (35%), and mobile spine (15%). It is a slow-growing, locally aggressive tumor with high recurrence rates.
Exam Pearl
Q: What histological finding is pathognomonic for chordoma? A: Physaliphorous cells (bubbly vacuolated cells) arranged in lobules within a myxoid matrix. These cells are positive for brachyury immunostaining, which is the most specific marker for chordoma.
Exam Pearl
Q: What is the Enneking staging system for spinal tumors and how does it guide surgery? A: The WBB (Weinstein-Boriani-Biagini) system adapted for spine divides the vertebra into 12 sectors and 5 layers (A-E). It determines surgical margin possibilities - wide excision (en bloc) is possible when tumor is contained within sectors/layers that can be resected together.
Exam Pearl
Q: What radiation modality is preferred for chordoma and chondrosarcoma of the spine? A: Proton beam therapy or carbon ion therapy. These tumors are relatively radioresistant to conventional photon therapy but respond to particle therapy which delivers higher doses with sharp dose fall-off protecting the spinal cord.
Australian Context
Primary bone tumors of the spine are managed through specialized sarcoma centers with multidisciplinary teams including spine surgeons, musculoskeletal oncologists, radiation oncologists, and medical oncologists. In Australia, major sarcoma services exist in tertiary centers such as the Peter MacCallum Cancer Centre, Royal Prince Alfred Hospital, and Princess Alexandra Hospital.
Access to proton beam therapy is available through the Australian Bragg Centre in Adelaide for patients with chordoma requiring adjuvant radiation therapy. The Australasian Sarcoma Study Group coordinates clinical trials and registry data for rare sarcomas including spinal tumors.
Given the rarity of these tumors and complexity of treatment, referral to a specialist sarcoma service is strongly recommended for all patients with suspected primary malignant spine tumors before biopsy is performed.
References
- Boriani S, Bandiera S, Biagini R, et al. Chordoma of the mobile spine: fifty years of experience. Spine. 2006;31(4):493-503.
- Fuchs B, Dickey ID, Yaszemski MJ, et al. Operative management of sacral chordoma. J Bone Joint Surg Am. 2005;87(10):2211-6.
- Murphey MD, Andrews CL, Flemming DJ, et al. Primary tumors of the spine: radiologic pathologic correlation. Radiographics. 1996;16(5):1131-58.
- Marco RA, Gentry JB, Rhines LD, et al. Ewing's sarcoma of the mobile spine. Spine. 2005;30(7):769-73.
- Stacchiotti S, Sommer J. Building a global consensus approach to chordoma: a position paper from the medical and patient community. Lancet Oncol. 2015;16(2):e71-83.