14 Primary and Metastatic Spinal Tumors 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. • 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%). • 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. Table 14.1 Classic physical examination findings in metastatic spine tumors
14.1 Introduction
14.2 Background and Etiology
14.3 Presentation and Physical Examination Findings (Table 14.1)
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 |
– Bowel and bladder dysfunction.
– Pathologic reflexes.
• Pathologic fractures with subsequent kyphosis.
• Weight loss.
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):
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).
∘ 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.
14.6 Primary Spinal Tumors (Figs. 14.2, 14.3, Tables 14.2–14.5)
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:
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.)
∘ 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.
