Bowel and bladder dysfunction may develop before diagnosis in up to half of patients with cord compression.⁶ Patients with compression at the level of the conus medullaris may present with isolated sphincter dysfunction, but it is far more common to see associated lower extremity impairments. The neurologic assessment in these patients must include an evaluation of bladder function.

Imaging Techniques

Plain Radiographs

Plain roentgenograms should be the first test in any case where a neoplasm is suspected. Anteroposterior (AP) and lateral views of the involved vertebra can provide considerable information about the nature and behavior of the lesion and may be sufficient to identify some characteristic tumor types. Even when the specific tumor type is not implicated, the benign or malignant nature of the lesion may be deduced from the pattern of bony destruction. Geographic patterns of bone destruction suggest a slowly expanding lesion, typically benign; more rapidly growing tumors produce a moth-eaten appearance; highly malignant, aggressive lesions produce a permeative pattern of destruction.⁷ However, because radiographic evidence of bone destruction is not apparent until between 30% and 50% of the trabecular bone has been destroyed, early lesions may be hard to detect.⁸ Twenty-six percent of patients with spinal metastases will have occult lesions undetectable on plain radiographs.⁹

The most classic early sign of vertebral involvement is the “winking owl” sign seen on the AP view. The loss of the pedicle ring unilaterally results from the destruction of the cortex of the pedicle, usually by tumor invading from the vertebral body proper. Vertebral collapse secondary to erosion of bone by tumor is another common radiographic finding. A pathologic compression fracture may be difficult to differentiate from a traumatic injury, particularly in patients with osteoporosis. Periosteal reaction that seems too old for the acute trauma or the presence of a soft tissue mass or soft tissue calcifications should alert the physician to obtain more definitive diagnostic tests. Vertebral destruction from pyogenic osteomyelitis can have a similar radiographic appearance; however, disc height will usually be reduced in infection and maintained with neoplastic processes.

Bone Scan

99mTechnetium bone scans are commonly used to detect neoplastic disease of the musculoskeletal system. Their superior sensitivity makes them ideal to detect lesions in symptomatic patients with negative or equivocal radiographs. The ability to scan the entire body makes bone scans advantageous to determine the extent of dissemination in patients with known systemic disease and to define the most accessible lesion to biopsy in patients with an unknown primary malignancy. More recently, intraoperative bone scans (IOBSs) have been used for osteoid osteomas. These benign lesions of the spine can cause significant pain and spinal deformity in the pediatric population and are often surgically elusive. IOBSs have been shown to minimize the need for multiple surgical procedures to ensure complete resection. As such, IOBSs have been shown to be highly sensitive for lesion localization and verification of complete surgical extirpation.¹⁰ However, the main disadvantage of bone scans is their poor specificity because non-neoplastic pathology, most often osteoarthritis, can also cause focal areas of increased uptake. The addition of single photon emission computed tomography (SPECT), a recent technologic advancement, however, improves the predictive value of planar scans by better defining the anatomic location of uptake.^11,¹²

Computed Tomography Imaging

Computed tomography (CT) scanning offers improved specificity in the detection of spinal neoplasms. CT has proven highly sensitive to alterations in bone mineralization and is able to demonstrate neoplastic involvement far more reliably than plain radiographs. Lesions may be visualized at an earlier time in their development, before extensive bony destruction or intramedullary extension has occurred, and before cortical erosion has progressed to the point of impending fracture. However, CT is only effective when the right area is studied; a preliminary bone scan may help identify the correct level for CT scanning, improving the yield in diagnostically difficult cases.

With the advent of portable CT scanners, expanded use of intraoperative CT scanning for spinal surgery has been reported. Because CT scanning provides excellent visualization of osseous pathology, it can be extremely helpful in the evaluation of tumor resections during complex spinal operations.¹³

Myelography

Once the only reliable way to assess spinal cord and nerve root compression, myelography has now given way to magnetic resonance imaging (MRI) in most instances. In combination with CT, however, it remains a valuable tool for detecting cord compression due to fracture and bony impingement, especially in patients who cannot undergo MRI.

Magnetic Resonance Imaging

Because of its superior sensitivity and specificity, MRI has become the method of choice to evaluate the spine. It is well tolerated and safe with no exposure to radiation. MRI provides the best imaging of neural structures and can clearly define intramedullary, intradural, and extradural compressive lesions, as well as the extent of the lesion causing the compression, things that myelography cannot do (Fig. 85–1). The ability to obtain multiplanar images and to better delineate soft tissue structures make it invaluable in diagnosis and treatment planning. Whole spine MRI is also the best method to evaluate and direct treatment in a patient with suspected spinal cord compression and known malignancy.

FIGURE 85–1 A, Spinal cord compression from a dorsal T2 metastasis. Extent of cord compression and tumor volume is defined by magnetic resonance imaging. B, Computed tomography imaging demonstrates extent of bony destruction. C-D, Lateral and anteroposterior views following posterolateral decompression, fusion, and segmental instrumentation. The patient had pain relief and full recovery of function.

MRI can detect neoplasms in the spine because normal marrow is replaced with tumor tissue with increased cellularity and extracellular water content.¹⁴ Thus most neoplasms have low signal intensity on T1 and high signal on T2. Fat suppression techniques combined with intravenous gadolinium further increase the contrast between normal fatty marrow and tumor tissue, making MRI the imaging technique with the earliest ability to detect neoplasm.¹⁵

These methods can also help to distinguish pathologic fracture due to osteoporosis versus malignancy. Malignant lesions usually have a more ill-defined margin, involvement of the pedicle, marked enhancement, and frequent paravertebral soft tissue extension while benign causes of vertebral compression usually still have fat present within the body, do not involve the pedicle, demonstrate more focal edema, and do not have an associated soft tissue mass.^16,¹⁷ Infection can also be differentiated from neoplasm on MRI because infectious processes usually involve the disc space and endplate and incite a significant amount of edema. Neoplastic lesions are often more defined, do not involve the disc or endplates, and are associated with limited edema.¹⁴

Summary Imaging Appearance

The imaging appearance of primary bony tumors of the spine and simulating lesions of the spine has been described recently. There are specific imaging characteristics of benign and malignant lesions in the spine that can be described as follows. Benign bone tumors commonly appear as well circumscribed. As slow-growing lesions they may present with a calcified or sclerotic matrix. Malignancy on the other hand is often characterized by aggressive permeative lesions with bone destruction, cortical invasion, and associated soft tissue mass. CT may be helpful in characterization of the tumor matrix, exact location, extension and osseous changes, whereas MRI is superior for evaluation of the associated soft tissue mass, bone marrow infiltration, and intraspinal extension.¹⁸

Biopsy Techniques

The importance of a carefully planned biopsy cannot be overemphasized. Once the biopsy incision has been made, there are few choices left in planning the definitive tumor removal. When the surgeon selects an approach for biopsy, he or she is committed to that approach from thereon. The hazards of biopsy seen in musculoskeletal tumors of the extremities are doubly apparent in the axial skeleton. The incidence of inadequate or inappropriate biopsy that significantly alters a patient’s care is greater than one in three overall and probably higher in lesions of the spine.¹⁹ This risk is reduced significantly when the biopsy is performed by the treating, rather than the referring, physician.

Three forms of biopsy are available to the surgeon: excisional, incisional, and needle biopsy or aspiration. On occasion a posterior lesion may prove suitable for an excisional biopsy, but most lesions of the spinal column will require either an incisional or needle biopsy. Needle biopsies are subject to sampling errors and provide a small specimen for evaluation (Fig. 85–2). The primary role of needle biopsy is confirmation—confirmation of metastatic disease, of recurrence of a known lesion, or of sarcomatous histology in an otherwise classic clinicoradiologic presentation of osteosarcoma.²⁰ Culture results may also be obtained when infection must be ruled out.

FIGURE 85–2 A, Percutaneous needle biopsy of C2 osteoblastoma. B, Computed tomography scan-directed needle biopsy of T6 metastatic breast cancer.

The incisional biopsy should be the last step in the staging of the patient, performed just before the definitive surgical resection.²¹ A number of basic principles should be observed when performing the biopsy. The biopsy incision should be placed so that it may be excised with the tumor during the definitive procedure. Transverse incisions must be avoided, and the tumor approached in the most direct manner possible. Tissues should be handled carefully, and hemostasis should be meticulous so that hematoma does not carry tumor cells distant from the primary site. Bone should not be removed or windowed unless absolutely necessary. The specimen obtained should be large enough to allow histologic and ultrastructural analysis, as well as immunologic stains. The margin of the soft tissue mass is often most diagnostic because central portions are often necrotic. The surgeon should take care not to crush or distort the specimen, so as to maintain its architecture. If a soft tissue component exists, a frozen section should be obtained. Finally, if the definitive excision is to follow the biopsy under the same anesthetic, it is essential that all instruments used during the biopsy be discarded. The field should be redraped, and the surgeons should change gowns and gloves before the excision is begun. This same precaution should be followed in obtaining the bone graft for spinal reconstruction.

The general feasibility and safety of en bloc resection for primary spine tumors has been evaluated by analyzing (1) the effect of incisional biopsy performed before definitive en bloc resection and (2) the rate of achievement of disease-free margins, morbidity, mortality, and health resource utilization. En bloc resection can be considered when determining surgical and oncologic staging, with the key step being to obtain a tissue diagnosis using the premise that the best chance for surgical cure in primary tumors of the spine is by en bloc resection with disease-free margins.

A recent review of the literature determined that the Weinstein-Boriani-Biagini tumor staging system accurately predicted the attainment of wide or marginal en bloc resection in 88% of cases.²² There was a clear increase in tumor recurrence when intralesional procedures were performed before the definitive en bloc resection. Tumor recurrence significantly shortened patient survival. Surgical complication rates ranged from 13% to 56%, and mortality ranged from 0% to 7.7%. The authors concluded that (1) incisional biopsy or intralesional resection significantly increases the risk of local recurrence. Therefore transcutaneous CT-guided trocar biopsy was recommended instead.

It has been recommended that for primary spine tumor, the surgeon who performs the definitive surgery should ideally perform or direct the biopsy procedure. In addition, the authors recommended that en bloc resection is achievable if staging determines that it is feasible and that these surgeries should be done at experienced centers with multidisciplinary teams.

Tumors

Advanced spinal imaging has increased discovery rates of tumors. Most of these lesions are metastatic in origin. Nonetheless, a significant number of the lesions are primary spine tumors. When classified by their cell of origin, they can be classified by bony tumors, cartilaginous tumors, vascular tumors, plasma cell dyscrasias, and tumors that arise from embryonic rests. Further classification of these tumors into malignant or benign subtypes is based on their clinical progression, histopathologic evidence of invasiveness, and response to therapy.

Primary Tumors of Bone

Primary bone or soft tissue tumors arising in the spine are uncommon. In reviewing 82 primary neoplasms of the spine seen over a 50-year period at one center, 31 benign and 51 malignant lesions were identified, representing 8 benign and 9 malignant tumor types.² All six cervical neoplasms in this series were benign, whereas two thirds of all thoracic, lumbar, and sacral primary tumors were malignant. Seventy-five percent of tumors found in the vertebral body were malignant, compared with only 35% of those in the posterior elements. For patients older than 18 years, 80% of primary tumors proved to be malignant but in children and adolescents only 32% of lesions were malignant. The 5-year survival in this series was 86% in patients with benign tumors and 24% in patients with malignancies.² Bohlman’s review of 23 patients with primary neoplasms of the cervical spine also showed a marked difference in tumor type with patient age. In that series all patients younger than 21 years old had benign tumors, whereas 10 of 14 (71%) patients older than 21 had a malignancy.²³

Benign

Osteochondroma

Although osteochondromas are the most common benign tumor of bone, only 3% occur in the spine in the solitary form and only slightly more in multiple osteochondromatosis.²⁴ They are cartilage-capped bony projections arising from an abnormality in the perichondral ring. These lesions are usually asymptomatic in patients in the second and third decades of life, although patients may present with a painless mass. Rarely, patients may have neurologic compromise as a result of the lesion impinging on the canal or a nerve root. This scenario is more common in patients with multiple osteochondromatosis and in cervical lesions. Of osteochondromas presenting with spinal cord compression, 56% were in the cervical spine, 38% were thoracic, and 6% lumbar.²⁵ Most of these lesions are not apparent on plain films. CT is usually necessary to determine the point of origin of the lesion, but MRI is necessary to define the cartilage cap and the proximity of the cord and other soft tissues. Because of the slow progression of the compressive cord lesion, excision of the tumor, en bloc or piecemeal, provides excellent recovery of neurologic function with little likelihood of recurrence (Fig. 85–3).

FIGURE 85–3 A-B, Osteochondroma at L3: anteroposterior and lateral radiograph views. C, Osteochondroma at L3: computed tomography (CT) scan. D, Osteochondroma at L3: CT scan 2 years postoperatively.

Although solitary spinal osteochondromas are uncommon lesions of the maturing adolescent skeleton, this lesion is much less common in older individuals. Only a few reports are available on osteochondromas in adults. In rare cases, lesions involving the spinal canal can cause low back pain and neurogenic claudication due to expansion of the lamina and extension into the spinal canal and adjacent facet joints.²⁶ When treating osteochondroma in adolescents, one has to consider the possibility of recurrence if symptoms do not abate. This rare complication of recurrence has only been reported in three cases of cervical osteochondroma.²⁷

Multiple hereditary exostoses with vertebral exostosis into the spinal canal are rare but must be considered if other skeletal lesions are present and multiple cervical exostotic lesions are found. This has been described in 68 of patients in whom exostoses arising from the spinal column have been described. Twenty percent of patients with multiple hereditary exostoses had lesions encroaching into the spinal canal. Patients with lesions inside the spinal canal were typically asymptomatic and neurologically normal, with radiographs that did not demonstrate the lesion. Compared with female patients, male patients were more likely to have spinal lesions and more likely to have lesions encroaching into the spinal canal (P = 0.014). Because of risk of neurologic injury, routine MRI to screen all patients with multiple hereditary exostoses has been recommended at least once during the growing years.²⁸

Aggressive “Benign” Primary Spine Neoplasms

Osteoblastoma, Aneurysmal Bone Cyst, and Giant Cell Tumor

In order to define an improved clinical care plan for osteoblastoma, aneurysmal bone cyst, and giant cell tumor, these lesions have been grouped together in a category of “aggressive, benign, osseous neoplasms.”²⁹ A panel of spine experts including oncologists, surgeons, and radiation oncologists graded the literature as either strong or weak. No prospective or randomized studies were found, reflecting the limited number of patients with aggressive primary osseous tumors. However, the osteoblastoma initial search identified 211 articles, of which 17 addressed spinal issues. The initial search for aneurysmal bone cysts revealed only 6 of 482 articles were pertinent, and only 8 of 178 articles on giant cell tumors focused on the treatment of spinal lesions. Authors found differences in clinical care but concluded that “surgical treatment should be directed at gross resection of the tumor, understanding that this may be limited by anatomic confines and the potential for morbidity.”

Osteoblastoma and Osteoid Osteoma

Osteoblastoma and osteoid osteoma are osteoblastic lesions differentiated primarily by size. These benign lesions show a propensity for spinal involvement, usually the posterior elements. Osteoid osteoma occurs in the spine in approximately 10% to 25% of cases, and osteoblastoma occurs in roughly 32% to 46% of cases.³⁰^–³³ Patients usually present in their second or third decade, and the most common complaint is of back pain. The pain is typically persistent and unrelated to activity and often is most noticeable at night. Although aspirin classically provides dramatic relief of symptoms, this is not universal. Patients with osteoblastomas may have dull, achy pain typical of other benign lesions.

Painful scoliosis can be another presenting symptom. In a large review,³⁴ 78% of patients with osteoid osteoma and 54% of those with osteoblastoma were found to have scoliosis. The lesions were almost entirely on the concave side of the curve and were more commonly in the thoracic and lumbar rathern than cervical regions. The scoliosis is thought to result from muscle spasm on the side of the lesion. Most curves will improve or resolve after removing the lesion. This may not be the case, however, if the scoliosis has been present for a prolonged period of time.

Patients with these lesions may also present with neurologic compromise, although this is much less common. Neurologic deficit is more often found in patients with osteoblastoma and when lesions involve the thoracic region.

Radiographic demonstration of osteoid osteoma is difficult (Fig. 85–4). The lesion, by definition less than 2.0 cm in diameter, is easily obscured among the overlapping shadows of the vertebral column. CT demonstrates the lesion well, but if the cuts are at the wrong level or too wide, the tumor may be missed completely. The most sensitive method of locating an osteoid osteoma is by bone scan. The technetium bone scan provides accurate localization of the lesion, decreasing the average duration of symptoms by providing an early diagnosis and allowing prompt treatment.³⁵

FIGURE 85–4 A, Computed tomography scan of osteoid osteoma at C6. Plain radiographs were interpreted as negative. B, Intraoperative stereotactic localization permits ablation through minimally invasive approach. C, Lateral localizing view shows proximity to neural elements.

Osteoblastomas become considerably larger than osteoid osteomas and may be quite apparent on plain radiographs. The lesion is characterized radiographically by the expansion of the cortical bone, maintaining a thin rim of reactive bone between the lesion and the surrounding soft tissue. There is often a rim of reactive bone separating the tumor from the rest of the medullary bone. Although the tumor may show stippling in some cases, there is rarely if ever a lobulated or soap-bubble appearance to these lesions.³² When involvement of the vertebral body is seen, it is limited and results from extension of tumor into the body from the pedicle (Fig. 85–5).

FIGURE 85–5 A, Osteoblastoma at T2: axial magnetic resonance imaging (MRI) demonstrates extraosseous extension. B, Parasagittal MRI shows occlusion of neural foramen.

MRI appearance of osteoblastoma is characterized by the localized inflammatory response the tumor causes. These inflammatory features can simulate malignant behavior on MRI, and an aggressive resection could be prompted for an otherwise benign lesion. Therefore it is critical to corroborate MRI findings, with other imaging and clinical data. Osteoblastoma is characterized by classic benign features on CT. In a recently reported case, a lumbar MRI revealed a sacral tumor with malignant features of marrow edema and enhancement, whereas a CT showed a well-circumscribed lesion without lytic changes or malignant bone formation.³⁶ A conservative resection was performed, and histopathology confirmed the diagnosis of osteoblastoma. The authors concluded that the MRI findings for osteoblastoma can be misleading and cautioned that CT should be used when evaluating benign tumors with known inflammatory responses on MRI.

The treatment for both osteoblastoma and osteoid osteoma is by excision. Excision provides reliable pain relief, and the spinal deformity is improved or disappears in the majority of patients.^30,³⁷ Although a complete excision is desirable, it is not always feasible in the spine. Curettage and bone grafting of vertebral osteoblastomas have provided satisfactory long-term results in the vast majority of cases.^32,³⁷ Intraoperative CT guidance or preoperative CT localization may aid in complete resection of these lesions with the least amount of destruction to normal tissues. Osteoid osteomas in particular are treated commonly in other areas of the body with radiofrequency ablation. Although concern for thermal damage to neural structures is quite valid, recent reports of its safe use in spinal lesions may lead to its careful use in this setting.³⁸ In other instances, stereotactic guidance systems may be used to provide a precise excision through a minimally invasive approach.³⁹

Aggressive osteoblastoma is another variant of osteoblastoma. It is more aggressive and has higher recurrence rates and is considered to be a borderline or intermediate osteoblastic tumor. Although the true incidence and distribution of this rare tumor is not known, complete surgical excision by en bloc resection and spondylectomy is indicated because recurrence rates of 10% to 15% have been reported. Transformation to osteosarcoma has been reported and is associated with multiple recurrences. A recent article reported a rare case of recurrent aggressive osteoblastoma of the thoracic spine and accomplished successful treatment by total en bloc spondylectomy.⁴⁰

Aneurysmal Bone Cyst

Aneurysmal bone cysts (ABCs) involving the spine are rare lesions that may be found at any level. They involve the posterior elements nearly 100% of the time (Fig. 85–6), but they may also commonly extend into the vertebral body. These benign, highly vascular osseous lesions of unknown origin may present difficult diagnostic and therapeutic challenges.^41,⁴² ABCs are often expansile lesions containing thin-walled, blood-filled cystic cavities that cause bone destruction and sometimes spinal deformity and neurologic compromise. ABCs occur mostly in children and young adults, and 75% of patients are younger than 20 years old at presentation. In the lumbar spine, vertebra plana as a result of an ABC has been described and the authors pointed out that an ABC should be considered in the differential diagnosis when vertebra plana is seen in pediatric patients.⁴³

FIGURE 85–6 A-B, Plain anteroposterior and lateral radiographs of L4 tumor involving the left L4 transverse process and pedicle. Diagnosis was osteoblastoma with elements of aneurysmal bone cyst (solid ABC). C-D, Preoperative computed tomography and magnetic resonance imaging scans of lesion. E-F, Anterior posterior and lateral radiograph views after resection of tumor involving zones II, III, and IVA (see Fig. 85–12).

These lesions tend to involve adjacent vertebrae and may involve three or more vertebrae in sequence. Patients typically present in the second decade of life with pain or neurologic symptoms. Radiographs typically demonstrate an expansile, osteolytic cavity with strands of bone forming a bubbly appearance. The cortex is often eggshell thin and blown out. Cross-sectional imaging with CT or MRI is helpful for diagnosis (fluid levels) and treatment planning.

The treatment of spinal ABCs remains controversial according to the literature. Treatment options include simple curettage with bone grafting, complete excision, embolization, and radiation therapy. Reconstruction and stabilization of the spine may be warranted if deformity and instability are present. Preservation of neurologic function may dictate surgical management. Nonetheless, complete excision offers the best chance of cure and spinal decompression if neurologic deficits are present. Treatment strategy should be aimed at complete excision whenever possible. Aggressive intralesional curettage and bone grafting may have higher local recurrence rates than complete excision of the lesion.⁴² Instrumented fusion will be necessary if the lesion or surgical excision compromises the stability of the spine. Preoperative selective embolization is helpful, especially in larger lesions.⁴⁴

More recently, selective arterial embolization with N-2-butyl cyanoacrylate has been described.⁴⁵ The study population comprised 20 male and 16 female patients with an age range of 3.3 to 60.8 years.⁵ Nine lesions were localized in the appendicular skeleton (1 in the upper and 8 in the lower limb), 4 in the thoracic cage (1 rib lesion and 3 scapular lesions), 17 in the pelvis and 6 in the spine (1 thoracic and 5 sacral localizations). Of the 55 embolizations performed, only 1 embolization was necessary in 22 cases (61%), 2 were necessary in 9 cases (25%), and 3 were necessary in the remaining 5 patients (14%). In ninety-four percent of patients, treatment was found to be effective with follow-up ranging from 0.9 to 5 years. Only seven patients underwent surgery during the embolization study. The authors reported on three complications (5%)—two cases of skin necrosis and one case of transient paresis—and concluded that arterial embolization with cyanoacrylate was a viable treatment for aneurysmal bone cysts. They recommended embolization as a less invasive, lower-cost, easily repeated, simpler procedure than surgery and it does not preclude surgery later.⁴⁵

In children, aneurysmal bone cysts may represent a particular challenge because fusion and stabilization with instrumentation are often avoided due to concerns over instability following future axial skeleton growth. Recently, two case reports of aneurysmal bone cyst in the cervical spine of children were published.⁴⁶ They both demonstrated deeply involved lesions with extensive bone destruction. Both were treated aggressively with resection, fusion, and stabilization with instrumentation. Both patients were reported to have had an uncomplicated postoperative course. At 36- and 18-month follow-up, both patients had no cervical spine instability or recurrence of tumor. The authors concluded that treatment of aneurysmal bone cyst in the cervical spine is challenging when it occurs in close proximity to neural and vascular structures.

Hemangioma

Vertebral hemangiomas are common lesions, occurring in approximately 10% of all patients, but they are rarely symptomatic or of clinical importance. They usually occur in the vertebral body but can extend to the posterior elements. Reports of deformity or pain associated with vertebral hemangiomas are uncommon, but cases of nerve root and cord compression have been documented, predominantly in the thoracic region (Fig. 85–7).⁴⁷ The diagnosis of vertebral body hemangioma can usually be made on plain radiographs, although cross-sectional imaging will provide more information about cord impingement or fracture. Plain films classically show prominent vertical striations produced by the abnormally thickened trabeculae of the involved vertebral body.

FIGURE 85–7 A, Lateral radiograph of a large, symptomatic lumbar vertebral hemangioma, showing faint vertical striations. B, Computed tomography scan demonstrates vertical trabecular struts and a large soft tissue extension. C, Magnetic resonance imaging (MRI) demonstrates vertebral involvement and soft tissue extension into spinal canal. D, Sagittal MRI demonstrates extent of soft tissue mass and lumbar stenosis.

Occasionally, spinal osseous hemangioma can mimic metastasis of a malignant tumor. This has been reported recently in a 44-year-old woman where the lesion was located in the seventh cervical vertebra.⁴⁸ On histopathologic examination the lesion showed reactive osteoid formation and nontypical osteolytic radiologic findings, strongly suggesting a metastatic process. This case report underlined the importance of including hemangioma into the differential diagnosis even if it is found in the cervical spine. Although hemangioma is rarely found in the cervical spine, treatment of supposedly malignant metastatic lesions could expose the patient to the risks of unneeded aggressive local and adjuvant treatments.

Spinal hemangiomas are radiosensitive and frequently respond to radiotherapy alone. Alternatively, ethanol injection into the lesion or traditional embolization are other minimally invasive methods of treatment, although careful technique is required.⁴⁹ When cord compression develops and surgical treatment is considered,⁵⁰ angiography is indicated to establish the vascular source for the tumor, to identify the primary vascular supply to the cord (the artery of Adamkiewicz), and for consideration of preoperative embolization. Smaller symptomatic lesions may be managed with vertebral augmentation. Recently, percutaneous treatment with vertebroplasty for aggressive and symptomatic vertebral hemangiomas has been reported in 24 patients.⁵¹ The authors reported the utility of vertebroplasty with good clinical results in all patients with pain relief within 24 to 72 hours even when epidural extension was present. They concluded that percutaneous vertebroplasty “is a valuable, mini-invasive, and quick method that allows a complete and enduring resolution of the painful vertebral symptoms without findings of fracture of a vertebral body adjacent or distant to the one treated.” Large destructive lesions occasionally require anterior reconstruction.

Giant Cell Tumor

Although rare reports of malignant giant cell tumors exist, the vast majority of these lesions are slow-growing, locally aggressive tumors that do not metastasize. Spinal involvement is usually seen in patients in their third and fourth decades, and symptoms may exist for many months before the patient sees a physician. Plain radiographs usually demonstrate an area of focal rarification, though some present with a more geographic lytic appearance and marginal sclerosis. Giant cell tumors are most commonly found in the vertebral body and may expand the surrounding cortical bone extensively as the tumor enlarges (Fig. 85–8). CT is especially important in the evaluation of these tumors preoperatively because complete resection is critical to the eradication of local disease. CT is also crucial in the early identification of recurrences and should be used in postoperative follow-up on a routine basis. Complete excision is the treatment of choice and should be attempted en bloc whenever feasible in the spine.

FIGURE 85–8 A-B, Anteroposterior and lateral radiographs of L5 giant cell tumor. C-D, Magnetic resonance imaging scan of L5 GCT: T2-weighted sagittal and axial images.

Giant cell tumors involving the spine have a poorer prognosis than extremity lesions due to their locally invasive nature and the difficulty in obtaining a wide margin. This results in high local recurrence rates.^2,⁵² Adjuvant treatment with radiation therapy was associated with unacceptably high rates of postirradiation sarcoma, often leading to the patient’s death. Recent reports have demonstrated favorable responses using megavoltage radiation therapy with low or no risk of radiation-induced sarcoma.^53,⁵⁴ With more aggressive surgical resection, radiotherapy is unnecessary and good disease-free survivals have been obtained without the risks of irradiation (Fig. 85–9).^52,⁵⁵

FIGURE 85–9 A, Giant cell tumor at T12. B, Lateral view radiograph 5 years after total vertebrectomy with no recurrence.

A series of 22 consecutive giant cell tumors (GCTs) of the cervical spine reviewed ⁵⁶ the clinical patterns and follow-up data of GCT arising in the cervical spine, correlating treatment and outcomes over time.¹ Patients underwent surgical treatment from 1990-2003. The choice of surgical intervention was based on the Weinstein-Boriani-Biagini tumor staging system. The authors employed two different protocols of surgical treatment: Eight patients underwent subtotal resection, there were 13 cases of total spondylectomy, and one additional patient had en bloc resection for a lesion in the posterior element of C7. Spinal reconstruction was done with autograft and anterior instrumented fusion or anterior and posterior combined instrumented fusion. Eighteen patients received postoperative adjunctive therapies. Twenty-one patients were available for mid- and long-term follow-up (average of 67.8 months, ranging from 36 to 124 months). They reported satisfactory neurologic recovery, and fusion rates were 100%. The local recurrence rate was 71.4% in patients who underwent subtotal resection but only 7.7% for total spondylectomy. Four patients died within follow-up, and all of these deaths were in recurrent cases. One patient developed pulmonary metastases. The authors recommended strictly en bloc resection but recognized that it is often not a feasible option in the cervical spine because of the involvement of critical neurovascular structures.

Eosinophilic Granuloma

Eosinophilic granuloma is a benign, self-limiting condition that produces focal destruction of bone. A process of unproven etiology, eosinophilic granuloma is most commonly seen in children before the age of 10 years, when treatment can be challenging because preservation of neurologic function is of imminent concern.⁵⁷ It can, however, occur in the adult spine as well, where it may present with local osteolysis.⁵⁸ Lesions of the skull are most common, but any bone may be affected; vertebral involvement occurs in approximately 10% to 15% of cases. Spinal involvement can be seen in any of the triad of syndromes in which the disease manifests itself—isolated eosinophilic granuloma; the multifocal, chronic, and disseminated form, Hand-Schuller-Christian disease; or the acute disseminated or infantile form, Letterer-Siwe disease. The vertebral body is typically involved, usually in the thoracic or lumbar spine. Patients usually present with pain, focal spasm (torticollis is common in cervical lesions), and mild to moderate kyphosis. Neurologic compromise develops in a significant number of patients and may be severe.

Early in the disease process radiographs show a central lytic lesion with poorly defined margins and permeative bone destruction. At this point the lesion may produce a marked periosteal reaction, and distinguishing it from osteomyelitis or Ewing sarcoma may be impossible. As the vertebral body collapses and settles, radiographs demonstrate the flattened disc of dense cortical bone retained between the two intact intervertebral discs. This “coin-on-end” appearance of vertebra plana (Fig. 85–10) is a classic finding in eosinophilic granuloma but is not pathopneumonic; a similar appearance can be produced by either infection or high-grade sarcoma. With such a broad differential, the importance of obtaining an adequate biopsy specimen before beginning treatment cannot be overstated.⁵⁹

FIGURE 85–10 A, Lateral radiograph view of eosinophilic granuloma at C7. B, Computed tomography scan.

The treatment of eosinophilic granuloma is somewhat controversial, but it is clear that many patients will heal their lesions without any treatment other than biopsy, often reconstituting much vertebral height.⁶⁰ Low-dose radiotherapy (500 to 1000 rads) has been advocated in the past, but this may be avoided in most patients. In those who present with a neurologic deficit, the established course of biopsy followed by irradiation and immobilization remains the most widely accepted.⁶¹

A retrospective case review of seven children with eosinophilic granuloma of the cervical spine identified therapeutic goals as spinal stability, preservation of neurologic function, and relief of pain, while keeping in mind that patients are still growing.⁵⁷ There were five boys and two girls (mean age: 10 years; range 4 to 16) with a mean follow-up of 19 years (range 8 to 29). The symptoms at presentation varied according to the localization of the tumor and treatment varied from observation alone, prolonged immobilization, systemic chemotherapy, curettage with or without bone grafting, corticosteroid injection, and low-dose radiation therapy depending on the severity of clinical presentation. The authors recommended surgery for a child presenting with neurologic involvement. On the basis of their experience, they concluded that children with vertebral interbody fusion can show normal alignment of the neck and maintain normal motion at long-term follow-up.

Malignant

Osteosarcoma

Approximately 2% of all primary osteogenic sarcomas arise in the spine, 95% from the anterior elements. Patients present with pain and often with neurologic compromise. A palpable mass may be a late finding. Metastatic lesions are also commonly present on diagnosis. Vertebral osteosarcoma (especially in the sacrum) is frequently secondary to previous Paget disease or radiation therapy, in which case prognosis is even more grim.^5,^62,⁶³ The radiographic findings include both lytic and sclerotic lesions, with cortical destruction, soft tissue calcification, and collapse in advanced cases. CT and MRI demonstrate intraspinal and paraspinal soft tissue masses more clearly, allowing more accurate preoperative planning.

Treatment of lesions in the spinal column is usually difficult, and the outcome in these tumors has traditionally been poor. Therapy consisting of limited tumor excision and radiotherapy provided median survival ranging from 6 to 10 months.^5,⁶² In hopes of improving survival in this and other spinal malignancies, a more aggressive surgical approach has been advocated in recent years. For osteosarcoma, this has resulted in longer survival times and some cures.^2,⁶³^–⁶⁵

A systematic review of the literature and consensus recommendations by an international expert focus group has recently reviewed and classified “evidence in the literature regarding (1) the role of neoadjuvant chemotherapy and (2) impact of extent of surgical resection on clinical outcome, particularly survival and local control, in patients with spinal Ewing sarcoma (ES) and osteosarcoma (OS).” This study revealed moderate-level evidence suggesting that neoadjuvant chemotherapy offers significant improvements in local control and long-term survival in osteosarcoma of the spine. This multimodality management is essential in lieu of weak evidence suggesting that en bloc resection provides improved local control and potentially improved overall survival. Neoadjuvant therapy portends the most favorable local control and long-term survival. En bloc surgical resection may improve overall survival and decrease risk of recurrence.⁶⁶

Ewing Sarcoma Family Tumors

Approximately 3.5% of all Ewing tumors arise in the spinal column, with the majority originating in the sacrum.⁶⁷ Patients are usually in the second or third decade of life and present with pain with or without constitutional symptoms. Neurologic compromise is reportedly present approximately 60% of the time.⁶⁷ These tumors are usually centered in the vertebral body, but extension into the posterior elements is common. On occasion, Ewing tumors can be mistaken for psoas abscess.² The permeative appearance of Ewing tumors on radiographs can make diagnosis difficult, even in advanced disease, and collapse of the vertebral body may produce a vertebra plana indistinguishable from that seen in eosinophilic granuloma.⁶⁸ MRI is the best modality to differentiate these neoplasms and to define the extent of the lesion including occasional epidural metastases. Surgical treatment is indicated for decompression of neural elements and stabilization of the vertebral column, but the treatment of choice for Ewing sarcoma involves multiagent chemotherapy and high-dose radiotherapy. Recent studies indicate that attempts at surgical extirpation in combination with systemic therapy and radiotherapy may improve prognosis.⁶⁹

Similar to osteosarcoma, moderate-level evidence has been found to suggest that neoadjuvant chemotherapy and multimodality management offer significant improvements in local control and long-term survival in patients with Ewing sarcoma.⁶⁶ Investigators found low-level evidence supported a weak recommendation that en bloc surgical resection provides improved local control but does not improve overall survival. Radiation therapy for spinal ES may also be used for local control either alone or to supplement incomplete resection.

A recent study attempted to determine the best local treatment combined with neoadjuvant chemotherapy for Ewing sarcoma family tumors (ESFTs) of the spine and sacrum.⁷⁰ The rate of local recurrence of ESFTs in the spine and sacrum was investigated when treated with neoadjuvant chemotherapy and locally by radiotherapy alone, or surgery, followed by reduced doses of radiotherapy. The authors followed 43 patients, 26 of whom were treated with neoadjuvant chemotherapy and locally by radiotherapy alone, and 17 by surgery followed by radiotherapy at reduced doses. The 5- and 10-year disease-free survival (EFS) rates were 37% and 30%, respectively, and the 5- and 10-year overall survival rates were 42% and 32%. Prognosis was unrelated to gender or age, tumor volume, chemotherapy protocol, or local treatment. Instead, outcomes seemed worse for patients with primary tumors located in the sacrum than for patients with tumors located in other parts of the spine (5-year survival ≥ 23% vs. 46%). Surgery seemed to have little beneficial effect because there were no differences between patients treated with radiotherapy alone and those treated by radiotherapy and surgery. Authors concluded that ESFTs in the spine and sacrum have a poor outcome, and prognosis is significantly worse than that of primary ESFT in other sites.

Chordoma

Chordoma is a relatively rare malignancy occurring in all adult age groups but is predominantly found in patients in the fifth or sixth decade of life. The tumor arises from remnants of the primitive notochord ⁷¹ found in the sacrococcygeal and suboccipital regions of the spine and occasionally from notochordal rests within the vertebral body in the thoracic or lumbar region.⁷² Although this tumor is characterized by its slow, relentless local spread, it is a fully malignant lesion capable of distant metastases. Initial symptoms are usually mild and progress slowly as the tumor expands. Chordomas may reach a considerable size before metastasizing, and symptoms of constipation, urinary frequency, or nerve root compression may appear before patients present to their physician. A firm, fixed presacral mass can usually be palpated on rectal examination.

Radiographically, chordomas are lytic lesions in the midline of the vertebral body or sacrum, usually associated with a soft tissue mass. CT is helpful to define the destruction of bony architecture, and MRI is mandatory to define the extent of the tumor for presurgical planning. Patient survival depends on local control of the tumor. Local recurrence of a chordoma is a grim prognostic sign, dramatically reducing the likelihood of cure. Surgical extirpation of the tumor is the only curative procedure, and a wide margin must be obtained (Fig. 85–11). En bloc excision is associated with the least risk of local recurrence but may be a terrifically challenging undertaking.^72,⁷³

FIGURE 85–11 A, Computed tomography scan of L3 chordoma involving zones IIIA and IVA and B (see Fig. 85–12). B, Magnetic resonance imaging scan of the same patient, T2 image (sagittal).

A recent study evaluated factors that contribute to improved local control and survival with chordoma. Forty-two patients underwent resection for sacral chordoma with 12 female and 30 male patients. The proximal extent of the sacrectomy was at least S2 in 32 patients. The authors reported a median survival of 84 months, and 5-year disease-free and disease-specific survival rates were 56% and 77%, respectively. Local recurrence and metastasis occurred in 17 (40%) and 13 (31%) patients, respectively. Local recurrence (P = 0.0001), metastasis (P = 0.0001), prior resection (P = 0.046), and higher grade (P = 0.05) were associated with a worse disease-free survival.⁷⁴ Factors associated with poor outcome and increased local recurrence rates include prior resections (P = 0.0001) and intralesional resections (P = 0.01). The authors reported that treatment of wide contaminated margins with cryosurgery and/or radiation was not associated with a higher local recurrence rate. Surgical resection of sacral chordoma was associated with significant morbidity and complications requiring rectus abdominis flaps in some cases to decrease wound complications (P = 0.01). Thirty-one (74%) patients reported that they self-catheterize, 16 (38%) patients required bowel training, and an additional 12 (29%) patients had a colostomy. Twenty-eight (67%) patients reported sexual dysfunction. Two (5%) patients died because of sepsis. The authors recommended avoiding intralesional resection because of higher local recurrence rates and worse survival. Newer methods of radiation therapy using proton beams or using intensity-modulated radiotherapy may decrease rates of local recurrence further with less morbidity, although long-term studies are necessary.⁷⁵

Chondrosarcoma

Approximately 7% to 10% of chondrosarcomas arise in the spinal column.⁷⁶ Most of these tumors are low grade, so they grow slowly and are relatively resistant to radiotherapy and chemotherapy. A high propensity for local recurrence leads to the poor prognosis of spinal chondrosarcoma. Most patients present with pain, some with a palpable mass if the tumor arises from the posterior elements. Neurologic compromise is common.

Radiographically, chondrosarcoma has a fairly characteristic appearance. In advanced disease there is a large area of bone destruction and an associated soft tissue mass with flocculent calcifications within it. If there is no soft tissue mass, the vertebral lesion may be primarily lytic, with sclerotic margins, and with no mottled calcification.⁷⁷ CT and MRI are invaluable in demonstrating the extent of the lesion and evaluating cord compromise.

Complete surgical excision is required to cure the patient with chondrosarcoma. This may be impossible to obtain in some vertebral lesions. Stener pioneered en bloc excision of chondrosarcoma of the spine in 1971.⁷⁸ All of the larger series since then have demonstrated the importance of obtaining negative margins in an en bloc fashion to increase disease-free survival.⁷⁹

When the management of sacral tumors requires partial or complete sacrectomy, reconstruction of the lumbosacral junction is necessary. Staged anterior/posterior en bloc sacrectomy with Galveston L-rod pelvic ring reconstruction or more modern variations thereof are often required. Understanding the anatomy and biomechanics of the spinopelvic apparatus and the lumbosacral junction, as well as having a familiarity with the various techniques available for carrying out sacrectomy and pelvic ring reconstruction, will enable the spine surgeon to effectively manage sacral tumors.¹

Solitary Plasmacytoma

Multiple myeloma and solitary plasmacytoma are two manifestations in a continuum of B-cell lymphoproliferative diseases. Because the natural history of these two lesions differs so significantly, the clinical distinction between solitary plasmacytoma and multiple myeloma remains pertinent.

True solitary plasmacytoma is a rare entity comprising only about 3% of all plasma cell neoplasms. Though the course of multiple myeloma is usually rapidly progressive and lethal, patients with solitary plasmacytoma may have prolonged survival if local control can be obtained. The 1-year mortality rate for patients with multiple myeloma involving the spine is 76%; 100% at 4 years.⁸⁰ The 5-year disease-free survival in solitary plasmacytoma is roughly 60%.⁸¹

The treatment of choice in spinal lesions of solitary plasmacytoma and multiple myeloma is radiation. Because of the radiosensitivity of this tumor, surgical treatment has less influence in determining outcome than it does in other tumor types. Surgical intervention is usually reserved for cases in which cord compromise or spinal instability is present. Resection of large solitary lesions may also reduce the overall tumor burden before radiotherapy. Although radiotherapy is effective in local control, it is not effective in restoring spinal stability. Fractures and progressive vertebral collapse may occur. For this reason, investigators have attempted to establish the probability of progressive vertebral collapse on the basis of the degree of involvement of the vertebral body at the time of diagnosis. Parameters described by Taneishi and Kaneda, as well as those of Heller and Boden, have been used to predict progressive vertebral collapse.

Dissemination of myeloma may occur after many years of disease-free survival, and routine follow-up is indicated for an indefinite period. Serum protein immunoelectrophoresis has proven the most accurate indicator of dissemination and should be followed closely after therapy is introduced. If dissemination does occur, systemic chemotherapy should be instituted. With this treatment the mean survival of patients with skeletal solitary plasmocytoma has been reported to be as high as 75% at 5-year follow-up.

Lymphoma

Lymphoma may present as a systemic disease with skeletal manifestations or as an isolated bony tumor referred to in the past as a reticulum cell sarcoma. Because the lesion has been considered a metastatic lesion by some authors, it is not consistently included in reviews of primary bone tumors. There is a distinction between primary and secondary lymphoma in terms of survival, with a distinctly better prognosis in the former than the latter.⁸²

Treatment usually consists of radiation therapy with or without chemotherapy. Surgical treatment is primarily limited to biopsy, cord decompression, or stabilization of pathologic fractures, though some recurrences after radiation treatment may need to be surgically resected.

Metastatic Tumors

Metastases are by far the most common skeletal tumors seen by the orthopedist, and the spine is the most common site of skeletal involvement.⁷⁵ Skeletal metastases are produced by almost all forms of malignant disease but are most commonly secondary to carcinomas of the breast, lung, or prostate and less frequently from renal, thyroid, or gastrointestinal carcinomas (Table 85–1). Multiple myeloma and lymphoma are common sources of disseminated skeletal lesions, though whether they are considered metastatic or primary lesions has varied from author to author. Breast, lung, prostate, and lymphoreticular disease account for approximately 60% of all spinal column tumors.

TABLE 85–1 Location of Primary Neoplasms Producing Metastatic Lesions of Bone: a Review of 5006 Cases

Primary Site	Totals (%)
Breast	2020 (40)
Lung	646 (13)
Prostate	296 (6)
Kidney	284 (6)
Gastrointestinal	255 (5)
Thyroid	110 (2)
Bladder	160 (3)
Total	5006

Tumors in Children

Spinal tumors are uncommon in children, but when they occur they present both short-term and long-term challenges. Aside from the usual complexities of treating the neoplasm itself, the added dimension in the care of children’s tumors is the prevention or management of spinal deformities that often develop as a result of treatment.

Tumors of the immature spine differ in type from those seen in adults, particularly in terms of the malignant lesions. Nearly 70% of primary bone tumors seen in children are benign.⁹² Osteoid osteomas and osteoblastomas, osteochondromas, and aneurysmal bone cysts account for more than 40% of all primary spinal lesions seen in pediatric patients. Malignant lesions, although less common, are predominantly from metastasis or contiguous invasion from neuroblastoma, embryonal carcinoma, and sarcoma.⁹³^–⁹⁴ These highly aggressive lesions have a poor prognosis regardless of treatment. Ewing sarcoma is the most common primary malignancy (Table 85–2),² but even more common is a metastatic lesion. Diagnosis in these patients may be challenging because presenting complaints may be nonspecific.

TABLE 85–2 Primary Tumors of the Pediatric Spine*

Tumor	Number (%)
Benign
Osteoblastoma	4
Osteochondroma	4
Aneurysmal bone cyst	4
Giant cell tumor	3
Eosinophilic granuloma	2
Osteoid osteoma	2
Hemangioma	1
Angiolipoma	1
Malignant
Ewing sarcoma	3
Chordoma	1
Osteosarcoma	1
Malignant giant cell tumor	1
Chondrosarcoma	1
Others	3
Total	31

* Primary bone tumors found in the spinal column in 31 patients younger than 18 years of age.

Leukemia

Another disease presenting in pediatric patients is leukemia. In 6% of children with leukemia, back pain and vertebral collapse are the initial findings at the time of presentation. During the course of the disease 10% will sustain a pathologic vertebral fracture, sometimes involving multiple levels.⁹⁵ When first seen, these children manifest a variety of nonspecific constitutional symptoms and the correct diagnosis is often hard to make. Lethargy, anemia, and fever occur commonly and often in combination. The peripheral leukocyte count is elevated in 60% of patients, and the erythrocyte sedimentation rate is also elevated. Radiographs may not demonstrate any focal abnormality, or they may show focal lytic lesions, occasional sclerotic lesions, or isolated periosteal reactions. It is important to keep in mind that radionucleotide scans are unreliable in patients with leukemia, in some cases showing no uptake in areas of obvious bony destruction. The presenting symptoms and signs mimic those seen in patients with osteomyelitis or joint sepsis, and this misdiagnosis is common. Keys to making the correct diagnosis in these confusing presentations are the identification of anemia, the recognition of those 40% of patients who are leukopenic at presentation, the presence of inconsistent bone scan results, and a high index of suspicion on the part of the examining physician.

Spinal Deformity

Progressive deformity may occur for any of a number of reasons after treatment of pediatric spinal tumors. As in adults, deformity may result from structural deficiencies caused by the erosion of bone by tumor or by aggressive surgical resection. These deformities may be more severe or progressive in children, however, particularly in the case of postlaminectomy kyphosis and particularly in the thoracic spine. The younger the child at the time of laminectomy, the more severe the eventual deformity is likely to be.⁹³ Irradiation and rib resection can cause iatrogenic scoliosis, as can a higher number of laminectomy levels. Surgical management of pediatric tumor patients must anticipate the later development of deformity and seek to minimize it. Deformities that are certain to progress must be identified early on, and treatment instituted to halt this progression.

Treatment

General

The goals of treatment for patients with spine tumors are to provide cure if possible, palliation and early return to activity if not, and a stable spinal column and normal or improved neurologic function in either case. Table 85–3 provides a general outline for the treatment of spine tumors.

TABLE 85–3 General Treatment Approach for Spine Tumors

Therapy	Indication
Observation	Indolent and clearly benign tumors (hemangioma, osteochondroma, bone island, bone infarct)
Radiotherapy	Metastatic lesions from a known radiosensitive primary (multiple myeloma, breast carcinoma)
Chemotherapy	Metastatic lesions from a known chemosensitive primary (thyroid)
Intralesional excision, curettage	Benign tumors with limited potential for recurrence (aneurysmal bone cyst, osteoblastoma), radiosensitive metastatic lesions with adjuvant radiation therapy
Marginal excision ± adjuvant cryotherapy or radiotherapy	Locally aggressive benign lesions (giant cell tumor), radiosensitive primary and metastatic lesions (plasmacytoma, breast and prostate carcinoma), low-grade malignancies
Wide excision	All primary malignancies without known metastases (osteosarcoma, chondrosarcoma, chondroma); solitary metastases with likelihood of prolonged survival (breast, prostate, renal cell carcinoma); locally aggressive benign tumors (giant cell tumor)

Indications for Surgery

Not all patients with spine tumors require surgery. Those with clearly benign tumors and those with diffuse metastases in whom the primary is known or where there is another, more accessible lesion can simply be observed. With the acceptance of more aggressive surgical methods, surgical indications have been expanded: (1) an isolated primary or metastatic lesion or a solitary site of relapse; (2) pathologic fracture or deformity with bony impingement producing neurologic symptoms or pain; (3) radioresistant tumors—metastatic or primary; (4) tumor progression despite or following radiotherapy; (5) segmental instability with significant pain or impending neurologic injury; and (6) inability to obtain tissue diagnosis by other means. All of these presume a patient who is healthy enough to survive surgery but are not incumbent on a long expected survival.

Staging

To treat spinal neoplasms appropriately, an organized, calculated approach must be applied in preoperative planning. The surgeon must understand the anatomic extent of the lesion in three dimensions and anticipate the stabilization and reconstruction that will be necessary. Although true anatomic compartments (as defined by Enneking ⁹⁶) do not exist in the spinal column, anatomic structures do provide natural planes for dissection and wide excision. The vertebral body, anterior and posterior longitudinal ligaments, intervertebral discs, and dura may all be resected to avoid leaving residual tumor behind. Neural, muscular, and vascular structures may all be sacrificed to obtain an adequate surgical margin in primary malignancies. Such an aggressive approach is justified: as in extremity surgery, a complete resection provides the best prognosis for both local control and cure of the disease.

The vertebral body may be divided into four zones, I to IV. Tumor extension is designated as A, B, and C for intraosseous, extraosseous, and distant tumor spread (Fig. 85–12).⁹⁷ Zone IA includes the spinous process and pars interarticularis along with the inferior facets. Zone IIA includes the superior articular facet, the transverse process, and the pedicle from the level of the pars to its junction with the vertebral body. Zone IIIA includes the anterior three fourths of the vertebral body, whereas zone IVA designates involvement of the posterior one fourth of the body, that segment immediately anterior to the cord. Zones IB to IVB are the extraosseous extensions of tumor beyond the boundaries of the cortical bone, and zones IC to IVC designate associated regional or distant metastatic involvement. Surgical approach is determined by the zones involved and the extent of the local tumor spread, while overall outcome depends on the degree of extension to other body systems, as well as the type and grade of tumor.

FIGURE 85–12 Anatomic extent of spine tumors by zone. A, Axial cut through L1 zones I to IV: A (intraosseous lesions confined within the boundaries of the cortical spine), B (extraosseous extension), and C (distant metastases) stages. B, Posterior view of L1 zones I to IV. C, Lateral views of L1. D, Resection planes for en bloc excision of zone I, II, or II/IV stage A lesions.

Surgical Approach

Many different surgical approaches are available to the spine surgeon, and variations to each have been described (Table 85–4). Choosing the correct approach for the given situation is, perhaps, the most important step in treating these conditions. The surgical approach selected must provide sufficient access for both tumor excision and stabilization of the spine thereafter. If both operations cannot be performed through the same incision, the surgeon must plan for a combined approach. An ill-planned approach may leave the surgeon unable to complete the excision of the tumor, a situation to be avoided if at all possible.

TABLE 85–4 Surgical Approaches to Spinal Neoplasms

Level	Anterior	Posterior
Upper cervical	Transoral	Midline
	Extraoral
	Extreme lateral
Lower cervical	Southwick-Robinson	Midline
Cervicothoracic/upper thoracic	Sternal splitting	Midline
	Low anterior costotransversectomy ± endoscopy	Costotransversectomy
Thoracic	Thoracotomy	Midline
	Costotransversectomy ± endoscopy	Costotransversectomy
		Transpedicular
Thoracolumbar	11th rib extrapleural-retroperitoneal	Midline
		Posterolateral
Lumbar	Retroperitoneal	Midline
	Transabdominal	Transpedicular
		Posterolateral

Zone I lesions are best approached posteriorly, and the extent of excision must be based on any soft tissue extension seen on preoperative studies. Zone II lesions are also more easily excised through a posterior or posterolateral approach and should be similarly stabilized. The need for stabilization following zone I and II resections depends to a great extent on the spinal segment involved. Extensive or multilevel laminectomies in the cervical or thoracic spine routinely lead to progressive and severe kyphosis, and posterior instrumentation prevents this by restoring a posterior column tension band to combat the normal tensile loads seen in these segments. In the lumbar segments kyphosis is less of a concern than translational deformities and back pain. Iatrogenic spondylolisthesis may occur any time an entire facet is removed or when more than 50% of both facets are removed at any one level.

Lesions in zone III should be approached anteriorly. Adequate resection of IIIA lesions can usually be obtained throughout the spinal column, but IIIB lesions should be carefully analyzed preoperatively to anticipate possible invasion or adherence to the great vessels of the thoracic cavity, retroperitoneal structures of the abdomen, or critical neurovascular elements, esophagus, or trachea in the cervical region. Reconstruction may be performed with or without internal fixation depending on the extent of the resection and the inherent stability of the residual elements.

Zone IV lesions that require a complete or en bloc excision must be managed through a combined anterior and posterior surgical approach. These lesions involve the most inaccessible region of the vertebral body and are the most difficult lesions to reconstruct; they provide major technical challenges to the surgeon before, during, and after the actual tumor resection. Zones I, II, and/or III must be crossed at some point to provide access to zone IV lesions, and frequently more than one zone may be involved with tumor. Complete excision can be obtained, though tumor margins must often be crossed. Excision requires vertebrectomy, essentially separating zone II from zones III and IV through combined approaches (Figs. 85-13 and 85-14), and in such cases both anterior and posterior stabilization is usually necessary. Failure to provide sure fixation and an adequate bone graft may result in loss of fixation, with catastrophic neurologic complications if hardware migrates into the canal or if excessive kyphosis develops.^76,⁹⁸

FIGURE 85–13 A-B, Illustration of reconstruction performed for L3 chordoma. C-D, Anteroposterior and lateral radiograph views taken 3 years postoperatively. No signs of recurrence to date.

FIGURE 85–14 Magnetic resonance imaging scan: anterior posterior (A), axial (B), and sagittal (C) views of T7 metastatic clear cell sarcoma adherent to the descending aorta. D-E, Anteroposterior and lateral radiograph views 3 years after tumor resection. A vascularized rib graft was used anteriorly off the internal mammary artery.

The best approach is also dictated by the level within the spinal column in which the tumor is found (see Table 85–4). Upper cervical lesions can be approached anteriorly via transoral, extraoral,⁹⁹ or extreme lateral¹⁰⁰ approaches. This allows resection, decompression, and reconstruction for anterior tumors. Most surgeons use the Southwick-Robinson anterior approach for lower cervical tumors.¹⁰¹ The anterior cervicothoracic junction and upper thoracic spine present an anatomic challenge to surgeons. Options are the sternal splitting approach, sterno-clavicular excision, the low anterior approach (a caudal extension of the Southwick-Robinson approach), and the posterolateral costotransversectomy. Splitting the sternum causes much morbidity, but the latter two approaches provide limited exposure. Endoscopic assistance provides a considerable advantage in these cases to allow complete vertebrectomy and anterior decompression in cases where en bloc excision is not indicated.¹⁰² Midline posterior approaches are used in the cervical and upper thoracic spine for posterior tumors and for instrumentation that is often required for adequate stabilization either in combination with an anterior approach or alone.

The standard approach to the anterior thoracic spine is a thoracotomy with rib resection. Good results have been obtained using this approach for anterior resection, decompression, and reconstruction in oncologic procedures.¹⁰³ Endoscopic assistance is also quite helpful as an adjunct to posterolateral approaches in the thoracic spine. Use of the eleventh rib extrapleural-retroperitoneal approach to the thoracolumbar junction gives the surgeon adequate exposure in most cases in this area.¹⁰⁴ The anterior lumbar spine can be approached via a retroperitoneal or transabdominal approach. The successful use of minimally invasive retroperitoneal procedures has allowed many surgeons to lean away from endoscopic assistance in the lumbar spine.¹⁰⁵

The thoracolumbar spine can be approached posteriorly via a midline incision for tumors of the posterior elements and for instrumentation and stabilization. The posterior transpedicular approach to the anterior thoracolumbar spine can be used for decompression and subtotal vertebrectomy. A simultaneous anterior and posterior approach,¹⁰⁶ a staged posterior and then anterior approach,^107,¹⁰⁸ or a posterior approach alone^109,¹¹⁰ can be used for total en bloc spondylectomy. (See “Resection” later for a more detailed discussion.)

Complete radiographic evaluation including CT and MRI allows accurate determination of the tumor location and extension and a more informed prediction of the tumor grade if not its actual tissue type. Additional laboratory and screening studies focus the differential further, allowing the surgeon to plan an operation that will adequately treat the tumor without exposing the patient to needless risks. Accurately determining the most likely tumor type in each case before surgery is important; overtreatment of benign disease can be nearly as disastrous as undertreatment of malignancy. The surgeon also needs to assess whether preoperative embolization of the tumor will be helpful, as it is in many cases such as metastatic renal cell carcinoma, hemangioma, and aneurysmal bone cyst. An algorithm has been developed for the evaluation of patients presenting for the first time with a spine lesion (Fig. 85–15).

FIGURE 85–15 Algorithm.

After the appropriate workup has been completed, the surgeon needs to then incorporate three crucial elements into a surgical plan. These are to determine (1) the proper margin of resection, (2) the need for neurologic decompression, and (3) the means of reconstruction.

Resection

The biology of the tumor and its stage largely determine the necessary resection margin and surgical approach (see Tables 85-3 and 85-4). Several studies have shown that obtaining a wide or marginal margin in both primary malignancies¹¹¹ and metastases¹¹²^–¹¹⁴ improves survival and local recurrence over intralesional margins. Obtaining the widest margin possible is essential in many locally aggressive or malignant primary tumors, particularly those that do not respond well to irradiation. A wide margin can be obtained in most isolated lesions in zones IA through IIIA because the tumor can usually be completely resected. Type IVA lesions can often be resected cleanly but only by removing the surrounding compartments as well. An adequate margin can be extremely difficult to obtain in type B lesions. IB to IVB lesions may not be completely resectable without producing serious neurologic deficits. In these cases surgery is marginal at best and often intralesional. The decision to attempt a wide or radical resection in these cases must be weighed against the risk of neurologic deficit.

Special mention should be made of sacral tumors. Partial or total sacrectomy with a combined anterior and posterior approach is effectively an amputation with the potential for a wide margin. Often the spine surgeon is assisted by general and/or vascular surgeons with this demanding procedure. The complication rate is high, mostly because of wound problems and colorectal complications. If nerve roots can be salvaged at least unilaterally, bowel and bladder function can be retained.^115,¹¹⁶

Decompression

Spinal cord compression is reported to occur in between 5% and 20% of patients with widespread cancer.^9,¹¹⁷ Although cord compression can also result from primary benign and malignant tumors of the spinal column, this occurs less frequently, and often the canal is effectively decompressed during the resection of the tumor. In all, spinal cord compression may result from one of four types of processes: (1) direct compression from an enlarging soft tissue mass, (2) pressure due to fracture and retropulsion of bony fragments into the canal, (3) severe kyphosis following vertebral collapse, and (4) pressure due to intradural metastases. The most common cause of cord compression is mechanical pressure from tumor tissue or bone extruded from the collapsing vertebral body.

Although the pathologic cause of spinal cord compression may vary, the symptoms of compression remain constant. Early recognition of these symptoms is crucial to early intervention and may prevent progressive and permanent neurologic injury. The first symptoms to appear are back pain, radicular or “girdle” pain, followed by weakness in the lower limbs, sensory loss, and loss of sphincter control. Although nearly all patients experience some localized back pain, patients with cervical and lumbosacral lesions are also likely to experience radicular pain. Patients with thoracic lesions occasionally experience radicular pain bilaterally, producing a segmental band or “girdle” of pain. Persistent, progressive back pain and radicular pain are the most useful warning symptoms of impending spinal cord compression but may precede actual cord compromise by days or years. Although bowel and bladder dysfunction may be seen at initial presentation, they are almost never isolated findings. When autonomic dysfunction occurs in the absence of motor or sensory loss, it is usually associated with a lesion of the T₁₀ to T₁₂ vertebral body.

Important factors in determining the prognosis for neurologic outcome include (1) tumor biology, (2) pretreatment neurologic status, and (3) tumor location within the spinal canal.

Tumor Biology

The intrinsic nature of each specific primary or metastatic neoplasm determines which will have slow or rapid growth, which will be invasive, which will produce metastases, and how long a patient is likely to survive after metastases are present.^87,^113,^117,¹¹⁸ Although metastatic lesions usually demonstrate behavior similar to their parent lesions, this is not always true; some metastases are more invasive or rapid growing than the primary lesions they come from. Rapid tumor expansion or vertebral erosion and fracture can produce acute cord compression and a poorer prognosis for improvement. Slower expansion produces gradual cord impingement, from which the patient has a much better chance of recovering. Understanding the tumor type and its biology allows the surgeon to reasonably predict if and when a specific lesion will endanger neurologic structures.

Neurologic Status

The neurologic status before treatment correlates strongly with post-treatment outcome whether in terms of likelihood of recovery, extent of recovery, or the ability to maintain or regain ambulation or bowel and bladder function. Between 60% and 95% of the patients who can walk at the time of diagnosis will retain that ability following treatment. By comparison only 35% to 65% of paraparetic patients will regain the ability to walk, and less than 30% of paraplegic patients will regain ambulation.^87,^113,¹¹⁹^–¹²¹ The rate of progression of the neurologic deficit also has clear prognostic significance. A patient who progresses from the earliest onset of symptoms to a major deficit in less than 24 hours has a poor prognosis for recovery irrespective of treatment. Conversely, compression that has evolved over a course of months has a far more favorable prognosis for recovery following treatment.

Tumor Location

Location of the neoplasm within the vertebral body or spinal canal determines what symptoms and signs may be produced and dictates the surgical approach required for treatment. Metastatic tumors and primary malignancies commonly arise in the vertebral body. When a tumor from an anterior lesion encroaches on the spinal cord, the anterior columns of the cord are compressed first. This leads to loss of motor function early on and progressive loss of sensory function as the cord is pressed back against the lamina. Because the mechanical loading of the vertebral elements differs from anterior to posterior, location also has value in predicting which lesions will cause vertebral collapse and segmental instability. For both of these reasons, tumors of the anterior and middle columns are associated with more frequent and more profound neurologic injury.

Location within the spinal column is also a factor in the development of cord compression. Neural compression occurs most commonly in the thoracic region of the spine, where the cord is relatively large with respect to the vertebral canal, and is less common in the thoracolumbar region. It occurs late in lower lumbar lesions, usually long after pain symptoms have become prominent.

Decompression Surgery

Cord decompression can provide dramatic improvement in neurologic function even in advanced states, depending on the rate of progression, interval from paralysis to treatment, and approach used to achieve cord decompression. Radiation therapy has been the traditional standard for treatment of cord impingement, particularly in metastatic disease. Frequently, however, metastatic tumors are radioresistant, the cord compression is secondary to bony impingement, or patients have reached the maximum dose of radiation. In these situations, surgery is indicated for decompression.

In the past, surgical decompression consisted of laminectomy, with removal of whatever tumor could be reached laterally in the gutters or through the pedicle. Unfortunately, the results of laminectomy are often no better than those with radiotherapy alone and posterior decompression has often resulted in iatrogenic instability postoperatively^. The results of surgical decompression through the anterior approach have been far more favorable and now offer a genuine improvement over the treatment with radiotherapy alone.

The cumulative experience of many authors has led to the following recommendations for decompression surgery in the spine: (1) Use the posterior approach in the upper cervical spine ⁸⁹; (2) use the posterior approach in the lower cervical, thoracic, and lumbar spine only for tumors of the posterior elements; (3) use anterior approaches for the majority of lower cervical, thoracic, and lumbar lesions because most tumors are located in the body in these regions^103,^119,¹²¹; (4) use alternative approaches in patients in whom medical factors preclude anterior approaches: costotransversectomy with or without endoscopic assistance in the thoracic spine (Fig. 85–16) and posterolateral transpedicular vertebrectomy in the thoracic and lumbar spine^102,¹⁰⁶; and (5) use a combined anterior and posterior approach or an extended posterior approach for en bloc spondylectomy or when the tumor involves many levels.^78,¹⁰⁷^–¹¹⁰

FIGURE 85–16 Video-assisted transpedicular decompression and reconstruction of T11 metastases. A-B, Axial and sagittal magnetic resonance imaging scans of T-12 metastases producing pain and spinal cord compression. C, After posterior laminectomy a left-sided transpedicular resection is carried out to expose the anterior lateral tumor mass and vertebral body. D, Transpedicular tumor resection carried out with rongeurs and curettes. E, Under endoscopic control, tumor adjacent to anterior spinal cord is resected with rongeurs and Epstein curettes. F, After wide decompression and vertebrectomy, a moss cage with autograft bone is introduced posterolaterally. G-H, Anteroposterior and lateral radiograph demonstrating anterior cage placement with posterior stabilization.

Reconstruction

After resection of a tumor, the spinal column will often need some form of reconstruction in order to restore the mechanical stability of the spine and compensate for the loss of bony elements. The surgeon must observe several key principles (Fig. 85–17). First, definitive treatment must restore the anterior weight-bearing column. This is mandatory in any case in which a significant amount of the anterior column has been resected at either one level or over many levels. Without reconstruction, collapse and kyphosis will result. Second, use posterior instrumentation to restore the posterior tension band after extensive laminectomy, especially in cases where facet joints have been removed. This will help to prevent kyphosis and can compensate for resected musculature. Third, combine anterior reconstruction with posterior instrumentation for larger resections. This includes subtotal and total spondylectomy and multilevel resections. Fourth, anticipate disease progression, especially in cases of metastasis. Problems can be avoided by including more levels in the fixation construct above and below the tumor, combining anterior and posterior instrumentation, and maximizing fixation points. Last, strive for biologic fusion in patients who are likely to survive more than 3 to 6 months.