14 Primary and Metastatic Spinal Tumors

14.1 Introduction

Primary and metastatic spinal neoplasms represent a series of complex pathologies that range from benign to life threatening. Detection of spinal neoplasms is further hindered by their indolent progression and vague symptomatology. As such, it is important for the practitioner to understand the nuances in examination and radiographic findings that are present in these patients. Furthermore, as these cases are often complex, understanding of the appropriate timing of nonoperative versus operative management is necessary to ensure the best possible clinical outcome.

14.2 Background and Etiology

Metastatic spinal lesions are much more common than primary lesions.
10-30% of new cancer diagnoses have spinal metastases at discovery:
- Spine is the most common site of metastatic bone disease.
Affects thoracic spine (68–70%) > lumbosacral spine (16–22%) > cervical spine (8–15%).

14.3 Presentation and Physical Examination Findings

(Table 14.1)

Most common clinical presentation is axial back pain (85–96%).
Progressive, nonmechanical, nighttime pain.
Neurological symptoms: radiculopathy or myelopathy:
- Changes in fine motor skills.
- Gait and balance instability.
- Bowel and bladder dysfunction.
- Pathologic reflexes.
Pathologic fractures with subsequent kyphosis.
Weight loss.

**Table 14.1** Classic physical examination findings in metastatic spine tumors
Primary tumors	Physical examination findings
Breast	Fixed, hard, nontender breast mass Nipple retraction
Prostate cancer	Nodularity in the prostate on digital rectal examination
Thyroid cancer	Painless, palpable thyroid
Lung cancer	Cough, hemoptysis
Renal cell carcinoma	Hematuria, flank pain, abdominal mass

14.4 Imaging

Plain radiography:
- Odontoid, swimmer’s, and upright views of the entire spine.
- Assesses spinal alignment, stability, presence of metastatic lesions, and presence of compression fractures.
- Identifies osteolytic and osteoblastic lesions:
  - Osteolytic: areas of severe bone loss due to excess osteoclast activity, appears as area of radiolucency.
  - Osteoblastic: areas of excess bone formation due to osteoblast activity, appears as areas of radiodensity.
- “Winking owl” sign: lysis of pedicular cortical bone (high sensitivity).
- Osseous lesions often not visible on plain radiographs until destruction of greater than 50% of the vertebral body has occurred.
Computed tomography (CT):
- Useful for surgical planning and visualization of bone destruction.
- Myelography to evaluate for impingement.
- Imaging of the chest, abdomen, and pelvis is required for staging.
- Poor overall sensitivity (66%).
Magnetic resonance imaging (MRI) ± gadolinium contrast:
- T1, T2, and short tau inversion recovery (STIR) weighted images (98.7% sensitivity).
- Pedicular involvement, edematous regions with defined borders, noncontiguous involvement are common findings.
- Contrast aids in the evaluation of soft tissue, epidural space, and spinal cord.
Bone scintigraphy: technetium-99m:
- Shows increased uptake in regions of neoplastic involvement.
- Low sensitivity for differentiating metastatic disease from osteoporotic compression fractures, infection, or degenerative changes.

14.5 Diagnosis and Staging

CT-guided biopsy:
- Gold standard for tissue analysis:
  - 76% sensitivity for sclerotic lesions; 93% sensitivity for lytic lesions.
- Percutaneous approach preferred; open approach may be utilized when percutaneous biopsy is negative but concern for tumor burden remains high.
- If the lesion is metastatic, biopsy of primary disease site is preferred.
Staging:
- Weinstein–Boriani–Biagini system ( Fig. 14.1 ):
  - Three-dimensional description of tumor invasion:
    - Twelve pielike zones rotating in a clockwise fashion starting at the spinous process.
    - Notes involvement of different vertebral layers: extraosseous soft tissue (A), superficial intraosseous (B), deep intraosseous (C), extradural extraosseous (D), intradural extraosseous (E).
    - Specifies the involved spinal segment.

**Fig. 14.1** Weinstein–Boriani–Biagini staging system for spinal neoplasms. (Reproduced with permission from An HS, Singh K, eds. Synopsis of Spine Surgery. 3rd edition. New York, NY: Thieme; 2016).

14.6 Primary Spinal Tumors

(Figs. 14.2, 14.3, Tables 14.2–14.5)

**Fig. 14.2** Primary benign tumors of the spine. **(a)** Axial section. CT scan showing osteoid osteoma of the thoracic spine. Note the lesion in the right-sided posterior elements. **(b)** Axial section. CT scan showing osteoblastoma of the thoracic spine. Note the lesion in the right-sided posterior elements. **(c)** Axial section. CT scan showing a giant cell tumor of the right-sided sacrum. **(d)** Anteroposterior view. Radiograph depicting an osteochondroma at the left-sided C5–C6 levels. (Reproduced with permission from An HS, Singh K, eds. Synopsis of Spine Surgery. 3rd ed. New York, NY: Thieme; 2016.)

**Fig. 14.3** Primary malignant tumors of the spine. **(a)** Anteroposterior view. Radiograph showing a large chondrosarcoma of the transverse processes of the lumbar spine. **(b)** Axial section. CT scan showing Ewing’s sarcoma of L2. Note the mixed lytic and blastic lesions present in the right lateral aspect of the vertebral body. **(c)** Sagittal section. T2-weighted MRI showing primary lymphoma affecting L5, leading to complete replacement of normal bone marrow and compression of the cauda equina.

**Table 14.2** Benign neoplasms of the spine
Tumor	Age	Gender	Location	Radiographic findings	Symptoms	Treatment
Osteoid osteoma	< 30 y	M > F	Posterior elements	Sclerosis surrounding a radiolucent nidus (15- to 20-mm diameter)	Back pain Pain relieved by anti-inflammatories (salicylates, NSAIDs, COX-2 inhibitors)	Anti-inflammatories En bloc resection if fixed spinal deformity
Osteoblastoma	< 30 y	M > F	Posterior elements Lumbar spine predominant	Similar to osteoid osteoma Radiolucent nidus > 20 mm diameter	Dull back pain ±Neural compression	En bloc resection ± Fusion if instability present
Aneurysmal bone cyst	< 20 y	F > M	Posterior elements 70% in thoracolumbar region	Axial deformity	Slowly progressive pain Palpable mass Possible deformity	En bloc resection ± stabilization if instability present
Osteochondroma	> 30 y	M > F	Posterior elements Primarily cervical region	Deformity Mature cortical and medullary bone continual with underlying bone	Pain and swelling in affected areas	En bloc resection ± stabilization
Giant cell tumor	20–50 y	F > M	Vertebral body	Expansile, lytic lesion with sclerotic rim Compression fractures	Back pain ± radiating pain Spinal cord compression	En bloc resection ± Adjuvant therapy if resection not viable
Eosinophilic granuloma	< 10 y	M > F	Vertebral body Thoracic region	Lytic lesions in vertebral body Vertebra plana	Persistent back pain Restricted ROM Deformity Diabetes insipidus (pituitary involvement)	Rest ± analgesics as necessary
Hemangioma	Variable	M=F	Thoracic and lumbar spine	Corduroy patterns with vertical striations	Often asymptomatic Possible pain, neurodeficits	Only if symptomatic Radiation therapy Transarterial embolization Vertebroplasty/kyphoplasty
Abbreviations: COX-2, cyclooxygenase-2; NSAIDs, nonsteroidal anti-inflammatory drugs; ROM, range of motion.

**Table 14.3** Primary malignant tumors of the spine
Tumor	Age	Gender	Location	Radiographic findings	Symptoms	Treatment
Solitary plasmacytoma	> 50 y	M > F	Vertebral body	Punched-out lytic lesions	Spinal cord compression Pathologic fractures Possible paraparesis	Radiotherapy ± surgical stabilization Follow response to treatment via M light chain levels on serum protein electrophoresis
Chordoma	< 40 y	M > F	Sacrum, C1–C2	T2-weighted MRI is the modality of choice High T2 signal intensity, soft-tissue tumor extension	Nonspecific low back pain Rectal dysfunction Radiculopathy	En bloc resection with clear margins Must warn patients of possible bladder, bowel, and sexual dysfunction
Primary lymphoma	40–60 y	M > F	Vertebral body	Osteolytic lesions Ivory vertebrae	Local pain Spinal cord compression	Decompression via laminectomy + systemic chemo- and radiotherapy
Chondrosarcoma	> 40 y	M > F	Vertebral body	Bony destruction Soft-tissue mass with matrix calcification	Pain Neurologic deficit	En bloc surgical resection
Osteosarcoma	< 20 y	M > F	Vertebral body	Mixed lytic and sclerotic lesions with cortical destruction	Pain Neurologic deficit due to cord compression	En bloc local excision Radiation and chemotheapy
Ewing’s sarcoma	< 20 y	M > F	Vertebral body	Mottled, moth-eaten appearance Irregular bone destruction with ill-defined margins Soft-tissue mass	Pain, swelling Systemic symptoms (fever) Neurologic deficits due to cord compression	Combined radiation and chemotherapy Surgery reserved for cases with instability and neurologic deficit
Abbreviation: MRI, magnetic resonance imaging.

**Table 14.4** Intraspinal neoplasms or cysts
Tumor	Age	Gender	Radiographic findings	Treatment	Symptoms	Notes
Schwannoma	20-50 y	M = F	Circular filling defect on myelogram	Surgical excision	Shooting pain and paresthesias upon nerve palpation	Most common spinal nerve or cord tumor Common in patients with neurofibromatosis (67%)
Meningioma	40–50 y	F > M	Solid, well-circumscribed lesion with broad dural attachment	Surgical excision	Pain, not reproducible on palpation	Primarily solitary lesions (90%) Involve multiple nerve fascicles and travel parallel to the nerve
Neurofibroma	20–30 y	–	Dumb-bell-shaped, circular defect Vertebral erosion and rib thinning	Surgical excision Adjuvant therapy if resection is incomplete	Pain ± weakness, possible paralysis Possible deformity	80–90% of spinal involvement is in the thoracic region More commonly intracranial

**Table 14.5** Intradural intramedullary tumors
Tumor	Age	Gender	Radiographic findings	Treatment	Symptoms	Notes
Astrocytoma	40–60 y	M > F	Expansile lesions with ill-defined borders Spans multiple vertebral segments	Surgical excision	Pain Sensory deficits Motor deficits distal to the spinal levels of involvement	Arise from glial cell transformation
Ependymoma	30–40 y	M = F	Areas of cystic change with cord expansion High-signal intensity intraparenchymally	Surgical excision	Back pain Paresthesia Sensory loss Lower extremity spasticity	Arise from cuboidal ependymal cells Most common adult primary spinal parenchymal neoplasm

14.6.1 Metastatic Spinal Tumors

(Fig. 14.4)

Background and etiology:
- Highest incidence between ages of 40 and 60 years.
- Affects males more often than females.
- Most common metastatic primary neoplasms:
  - Breast cancer.
  - Lung cancer.
  - Thyroid cancer.
  - Prostate cancer.
  - Renal cell carcinoma (RCC).
- Can spread via primary neoplasms by hematogenous, direct, or cerebrospinal fluid (CSF) extension:
  - Hematogenous extension can affect multiple levels via Baton’s venous plexus.
  - Most mechanistic evidence points toward tumor cell disassociation from a primary mass, penetration of the surrounding extracellular matrix, travel through lymphatic or blood vessels, and seeding of a distant site.
- Lesions often located in one of three compartments:
  - Extradural: most common.
  - Intradural–extramedullary.
  - Intramedullary.
Presentation:
- Similar to primary neoplasms:
  - Pain (83–95%).
  - Constitutional symptoms.
  - Motor, autonomic dysfunction due to metastatic spinal cord compression.
  - Sensory and motor dysfunction.
Imaging:
- Plain radiographs:
  - Osteolytic lesions in the majority of cases.
  - Osteoblastic lesions if primary lesion is prostate or breast cancer.
  - Pathologic and compression fractures.
  - Deformity.
- Bone scan:
  - Can reveal other metastatic lesions at an earlier stage than plain radiography.
- CT scan:
  - Improved visualization of bony anatomy.
  - Important for determination of primary neoplasm and other areas of metastasis.
- MRI:
  - Gold standard: allows for superior resolution of soft tissue, disk space, spinal cord, and nerve roots.
  - The degree of cord compression has been objectified via the metastatic epidural spinal cord compression scale:
    - Grade 0: bone disease only.
    - Grade 1a: epidural impingement without thecal sac deformation.
    - Grade 1b: deformation of the thecal sac without spinal cord abutment.
    - Grade 1c: deformation of the thecal sac and spinal cord abutment, but without cord compression.
    - Grade 2: spinal cord compression with visible CSF around the cord.
    - Grade 3: spinal cord compression with no visible CSF around the cord.
- Angiography:
  - Required when primary tumors are highly vascular (thyroid, RCC).
  - Allows for surgical planning and possible preoperative embolization to control hemorrhage.