Neoplasia



Fig. 21.1
Computed tomography (CT) of a thoracic spine psammomatous meningioma. Left: pre-operative axial view, the tumor with high density, indicating calcification, was located ventral-lateral to the spinal cord; middle: pre-operative sagittal view; right: post-operative sagittal view, the tumor was completely evacuated



MRI is now considered as the gold standard radiological image modality for spine tumors. Infection, inflammation, and neoplasia are usually clearly distinguished using modern MRI techniques. Moreover, MRI can also assist in differential diagnosis of pathologies of the neoplasm. MRI is particularly irreplaceable for providing detailed images of the soft-tissue and neural structures. Prior to the operation, spinal cord compression and tumor extent can be clearly depicted on magnetic resonance (MR) images. After surgery, MRI also provides important information to evaluate the extent of resection, degree of decompression of the neural tissue, and recurrence of the tumor. The image quality and resolution of MR images are superior to that of CT in terms of soft-tissue differentiation. Nevertheless, CT scans yield excellent evaluation of osseous tissue as well as vasculatures. Therefore, MRI and CT should be complementary to each other for not only preoperative planning but also postoperative follow-up [78]. The authors recommend obtaining both images for patients’ assessment and surgical planning.

Other supplementary image examinations, such as positron emission tomography (PET) and CT of the chest/abdomen/pelvis, would help evaluate the tumor metastasis throughout the whole body [32]. In addition to image examinations, a histopathologic biopsy is essential for primary spine tumors [32]. The histopathology of the spinal tumor is an important guide in the determination of the treatment strategy and surgical planning—which we discuss in following paragraphs. Percutaneous CT-guided biopsy of the spinal tumor is frequently performed for tissue diagnosis prior to the surgery [78]. The overall diagnostic accuracy can reach 90 %, and biopsy of lytic lesions can yield an accurate diagnosis in 93 % of cases [43]. In suspected malignant lesions after image evaluations, the biopsy tract should be marked, and thus the tract can be removed during surgery for definite complete tumor resection [32].



21.4 Primary Vertebral Tumor


Lateral approaches to the thoracolumbar spine have been well described and commonly exerted for primary spinal tumors. Many of these typical primary tumors, including aneurysmal bone cyst, hemangioma, giant cell tumor, neurofibroma, meningioma, plasmacytoma/multiple myeloma, and osteosarcoma, have been reported to be operated on through a minimally invasive surgery (MIS) lateral approach in the thoracic and lumbar spine areas [15, 61, 75].


21.4.1 Aneurysmal Bone Cyst


The annual incidence of aneurysm bone cysts (ABC) is 0.14–0.32 per 100,000 people [6, 66]. It has been estimated that ABCs may account for up to 10–20 % of all primary spinal tumors [22]. Typically, these ABCs are usually found in patients younger than 20 years old, with a median age of 13 years [41].

Histologically, ABCs are blood-filled cyst cavities with thin cortical septations [20]. Therefore, CT scans and MRI would demonstrate septa and fluid-fluid levels within the cyst cavity, which indicate multiple layers of blood product from old hemorrhages [27, 28, 66] (Fig. 21.2). The thoracic spine is the most common site of occurrence and the posterior element is usually affected, although the vertebral body may also be affected [36, 58].

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Fig. 21.2
Sacrum aneurysmal bone cyst, septa and fluid-fluid level within the cyst cavity. Left: sagittal T2-weighted magnetic resonance image (MRI); right: axial T2-weighted MRI

Traditionally, ABCs are treated with surgery (curettage, intralesional resection, or en bloc resection), selective arterial embolization (SAE) alone, or preoperative embolization plus surgery [6, 36]. There has been one multicenter study that compared the three kinds of treatment strategies and demonstrated no significant differences on local recurrence and survival between all these treatments. The study therefore concluded that spinal ABCs can be treated effectively with intralesional resection, en bloc resection, or SAE [6]. In general, preoperative embolization is considered effective in decreasing intraoperative bleeding during intralesional resection surgery.


21.4.2 Hemangioma


Hemangioma is the most common primary benign tumor of the spine in adults. Hemangiomas accounted for more than 10 % of primary spine tumors reported in autopsy studies [3, 21, 39]. However, most of these hemangiomas were asymptomatic and often incidentally discovered via examination for other purposes. They were usually solitary and found within the vertebral body [66].

The histologic features of hemangioma are aggregation of abnormal small vessel channels within bony trabeculae, and there may be also bony erosions [20]. On CT scans, hemangiomas usually demonstrate typically thickened trabeculae on both the axial and sagittal views. Therefore, these lesions earned the pathognomonic sign of “honeycomb” or “polka” [50]. There is usually high signal intensity on both T1- and T2-weighted MR images. A combination of both CT and MRI is common for the diagnosis of hemangiomas.

Although most hemangiomas are asymptomatic, they can cause pain, spinal cord compression, hemorrhage, or pathological fracture due to expansion of the tumor [21]. This phenomenon has also been associated with pregnancy [8].

Painful hemangioma or pathologic fracture without neurological deficit and cord compression can be effectively managed by vertebroplasty or kyphoplasty [1]. Surgery is usually reserved for cases of progressive neurologic deficits or spinal cord compression syndrome. Angiography before surgery may be a choice for evaluation of tumor vascularity and possible preoperative embolization to reduce bleeding during surgery [1, 21].


21.4.3 Osteosarcoma


Osteosarcoma is ranked as the most common primary bone malignancy. Osteosarcoma of the spine includes primary and metastatic malignancies and secondary malignancy which occurs as a result of previous radiation therapy or Paget’s disease [2]. Osteosarcoma has a bimodal age distribution. The first peak occurs during the 10–14-year-old age span, which usually affects long bones. The second peak occurs in those older than 65 years old and is frequently associated with Paget’s disease [55]. It is reported that only 1–2 % of osteosarcoma occurs in the spine and mainly involves the vertebral body [50, 67].

The major presentation of spine osteosarcoma is pain and spinal cord compression resulting from pathologic fracture or tumor invasion into the spinal canal [78].

In histopathological examination, osteosarcoma has typical spindle cells with nuclear pleomorphism [20]. Osteoid or bone production could also be found within the tumor. On CT scans, osteosarcoma may demonstrate lytic and destructive lesions with matrix mineralization. Using MRI, osteosarcoma can demonstrate a hypo-intense signal in T1-weighted images and a hyperintense signal in T2-weighted images [65]. Moreover, contrast-enhanced MR images may provide details about surrounding soft-tissue extension and the degree of spinal cord compression [78].

Management of osteosarcoma involves both surgery and chemotherapy. Ideally, en bloc resection of the malignancy provides the optimal tumor control, while subtotal resection is usually associated with tumor recurrence as well as metastasis. Due to the difficulty of en bloc resection in spinal osteosarcoma, traditionally the prognosis of osteosarcoma has been poor. However, with the updated multimodality treatment strategies combining neoadjuvant chemotherapy, adjuvant chemotherapy, surgery, and radiotherapy, the long-term survival rate from osteosarcoma has substantially improved [18, 19].


21.4.4 Giant Cell Tumor


Giant cell tumor (GCT) mainly occurs in the sacrum and is the most common primary benign tumor of the sacrum, with occasional involvement of other spinal segments [14, 31, 75]. Generally, GCTs are diagnosed at the ages of 30–50 years, with a slight female predominance [64, 65, 69].

Common presentations of GCTs are local pain and neurologic deficits caused by compression of neural elements. Large GCTs can cause paraparesis, sensory impairment, and cauda equina syndrome due to spinal cord or nerve root compression.

On histological examination, GCTs contain multinucleated giant cells originating from osteoclasts in a spindle-cell stroma. The stromal cells may demonstrate mitotic activity, which is the proliferative component of the tumor. Using MRI, GCTs are usually hypo-intense in T1- and T2-weighted images with intraspinal extension and with occasional areas of hemorrhage. Also, heterogeneous gadolinium enhancement is often demonstrated [44, 65]. In general, GCTs usually are large osteolytic lesions that destroy the bony cortex with surrounding tissue extension [44].

Although GCTs are classified as benign tumors, their behavior is sometimes locally aggressive. Therefore, wide en bloc resection is curative for GCTs, while intralesional resection may prompt local tumor recurrence either with or without adjuvant radiotherapy [40]. Preoperative embolization may decrease intraoperative blood loss due to the abundant vascularity in these GCTs. Furthermore, postradiation sarcoma has been observed in 11 % of patients who received radiation for primary or recurrent GCTs [40].


21.4.5 Plasmacytoma and Multiple Myeloma


Multiple myeloma (MM), or so-called plasmacytoma, is the most common primary tumor involving the vertebral column. Multiple myeloma is a lymphoproliferative neoplasm with systemic involvement including the hematopoietic, renal, and bony systems. Plasmacytoma more specifically and frequently refers to the soft-tissue form and a solitary lesion [4]. These tumors commonly affect older patients in their 60s and have a male predominance. The annual incidence of multiple myeloma is about 0.5–0.7 new patients per million people [17, 38].

On CT scans, the typical image findings of multiple myeloma and/or plasmacytoma are diffuse osteolytic and have characteristic “punched-out” lesions within single or multiple vertebrae. Commonly MM or plasmacytoma involves mainly the anterior column, and sometimes MM might not be diagnosed until symptomatic. Diffuse osteoporosis or multiple compression fractures of the vertebral bodies are not uncommon in patients with MM [65].

In histological examination, cells of MM originate from plasma B cells with blue or pink cytoplasm. Cytologic atypia and binucleated cells are the characteristic features of pathology that can be observed. Bone marrow examination generally shows both normal and atypical plasma cells increasing [20, 65].

As MMs are usually quite radiosensitive, radiotherapy is often recommended as the initial treatment alone [35]. Vertebroplasty and kyphoplasty are useful in pain reduction and restoration of spinal alignment after pathologic fracture of the vertebral bodies [45, 79]. Surgery of en bloc spondylectomy plus instrumentation fixation is reserved for patients with spinal canal invasion or progressive neurologic deficits and/or spinal instability.


21.4.6 Meningioma


Meningioma comprises nearly 25 % of intracranial tumors and is one of the most common benign brain tumors. However, meningioma originating from the spinal region is remarkably less than that of intracranial tumors and accounts for about 12 % of all meningioma. Among all the intradural spinal tumors, approximately 25–45 % were meningioma, and the annual incidence of spinal meningioma is estimated to be 0.5–2 per 100,000 persons, with a strong female predominance. The peak age of occurrence of meningioma is between the 60 and 80 years of age. The most common site of involvement is the thoracic spine, followed by the cervical then lumbar spine [25, 71].

Meningioma tumors are benign and slow-growing. From the aspect of histology, they are considered to be derived from arachnoid cells, although this is not fully understood [71]. In terms of spinal meningioma, MRI evaluation is the choice of diagnostic tools. MRI provides excellent tumor localization, tumor-neural structure relationship, and soft-tissue anatomy, and further information about the tumor itself can also be depicted preoperatively.

In a review of the literature, the recurrence rate of meningioma ranged from 0 to 14.7 %. The predictor of tumor recurrence includes the invasion of the pia mater, the Simpson’s resection grade, and the histological grade of the tumor [34, 62, 71]. Primary total resection of meningioma tumors is the standard of treatment (Fig. 21.3). Simpson grade 1 resection may not be necessary in pathology grade 1 meningioma. However, it is crucial to achieve Simpson grade 1 resection in atypical or high-grade meningioma to decrease the rate of recurrence [51, 71]. In a long-term follow-up study, a rate of up to 32 % recurrence of meningioma was observed in Simpson grade 2 resection after a mean follow-up of 12.2 years, while no recurrence was identified in Simpson grade 1 resection [51]. Therefore, the extent of resection is highly correlated to the rate of recurrence of meningioma.

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Fig. 21.3
T2-weighted magnetic resonance image (MRI) of T-11 spine metaplastic (ossified) meningioma. Left: pre-operative sagittal view, the tumor was located at ventral side of the spinal cord; right: post-operative sagittal view, tumor was totally removed. *vertebral body of T-11


21.4.7 Nerve Sheath Tumor


The nerve sheath tumor (NST), like neuroma or neurofibroma, is the most common spinal tumor, comprising one-third of primary spinal tumors [30]. NSTs are similarly distributed between both genders [15]. The most commonly diagnosed age of NST was in the patients’ fifth decade [42]. According to its anatomical location, NSTs can be divided into intradural-extramedullary, extradural, or dumbbell type, which has both intradural and extradural parts [57] (Fig. 21.4). These tumors are believed to originate from Schwann cell progenitors at the nerve root [30]. Most patients with a NST present with pain and paresthesia. However, there are patients who occasionally present with motor deficits if the tumor mass is large enough to cause compression of the spinal cord [30].

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Fig. 21.4
Magnetic resonance image (MRI) of lumbar spine neurofibroma. left: T2-weighted axial view with contrast; right: T1-weighted axial view with contrast. Arrow indicated tumor

Complete resection of a NST remains the gold standard management, despite the fact that it is not always feasible [13, 15, 30]. Traditional surgical approaches to NSTs of the thoracic spine include thoracotomy, (video-assisted) thoracoscopy, costotransversectomy, or a combination of the above. On the other hand, NSTs of the lumbar spine can be resected through posterior laminectomy or a posterolateral approach with partial or complete facetectomy, or lateral transpsoas approaches. Like resection of every other kind of tumor, instrumented fusion might be needed if the surgical approach compromises spinal stability, such as facetectomy [15].


21.5 Surgical Treatment for Primary and Metastatic Spine Tumors


Surgical treatment for spine tumors ranges from vertebroplasty [16], open anterior transthoracic, thoracotomy or retroperitoneal approaches [23, 26], an open posterior approach (transpedicular, costotransversectomy), a thoracoscopy-combined approach [26], and minimally invasive approaches [52, 80].


21.5.1 Open Surgery


The indication of traditional open surgery for thoracic and/or lumbar spine tumors includes medical-intractable pain, spinal cord compression, and instability [32]. The goal of an operation is to achieve complete tumor removal, local tumor control, and eventually disease control. The treatment strategy is mainly dependent on tumor histology. Each differential diagnosis of a primary malignant tumor, primary benign tumor, or metastatic tumor, or of spinal osseous tumors has different treatment strategies and goals.

For primary malignant vertebral tumors, the standard operative procedure of choice is en bloc resection plus adjuvant radiotherapy for best cure [11, 32]. On the other hand, intralesional resection plus radiotherapy may be sufficient for primary benign tumors [24, 32]. Many studies have demonstrated that en bloc spondylectomy provides a higher rate of tumor control, a lower rate of recurrence, and a longer term of disease-free survival for primary malignant vertebral tumors [5, 9, 11, 49, 70, 7274]. Boriani et al. reported a lower recurrence rate (22.4 %) following en bloc resection compared to non-en bloc resection (100 %) for chondrosarcoma [5]. In a study by Talac et al., a significant lower recurrence rate (11 %) following “en bloc resection with negative margin” was noted, compared to “piecemeal resection with negative margin” (33 %) and “resection with positive margin” (70 %) for primary sarcoma [73]. Sciubba et al. published a study that Ewing’s sarcoma and osteogenic sarcoma had improved rates of local tumor control after en bloc resection [70]. Furthermore, Ozaki et al. reported significantly better survival rates in patients with wide resection than those who had non-wide excision (biopsy or intralesional) for spine osteosarcoma [56].

The technique of en bloc resection of these spinal tumors can be challenging and is sometimes only achievable with sacrifice of some neural tissue. Therefore, en bloc spondylectomy usually involves experienced orthopedic or neurological surgeons, and it is not uncommon to combine both anterior and posterior/lateral approaches. There are major perioperative complications, such as spinal cord injury, unintended durotomy, and vascular injury to aorta and vena cava. The complex operation often results in spine instability that requires reconstruction and instrumented fusion of the vertebral column.

For metastatic tumors of the spine, surgical management can be effective in the relief of symptoms and in the improvement of life quality. Surgical decompression or evacuation of the tumor mass could provide better pain control, regain or maintain mobility, and offer improved sphincter control [29]. For these metastatic tumors of the spine, the surgical goal is mainly palliative and is better reserved for patients whose life expectancy is considered more than 3 months [10]. Although the final outcome depends on the status of the primary oncological disease, surgery is often very effective to relieve intractable pain, spinal instability, or neurologic compromise.

Surgical strategies to manage spinal osseous metastatic tumors range from intratumoral resection to en bloc resection. The various approaches include direct posterior decompression with or without posterolateral fusion, costotransversectomy with corpectomy and placement of interbody support and bone graft with posterolateral fusion, thoracotomy with corpectomy and cage reconstruction, retroperitoneal approaches, and vertebroplasty/kyphoplasty [32]. In a landmark study by Patchell et al., direct decompressive surgery plus postoperative radiotherapy was superior to treatment with radiotherapy alone for patients with spinal cord compression caused by metastatic cancer. Direct decompressive surgery provided improvement in ambulation, greater pain control, and less corticosteroid use [60].

The optimal paradigm of treatment for these spinal tumors remains uncertain. Cloyd et al. published meta-analysis and a systemic review of the present literature focusing on the prognosis of primary and metastatic spine tumors after treatment. The median time to recurrence was 113 months for the primary tumors and 24 months for the metastatic tumors. Disease-free survival rates at 1, 5, and 10 years were 92.6 %, 63.2 %, and 43.9 %, respectively, for the primary tumors, whereas the rates were 61.8 %, 37.5 %, and 0 %, respectively, for the metastatic tumors [11]. Furthermore, this review study also pointed out the risk factors of tumor recurrence, such as old age, male sex, previous metastatic tumors, and osteosarcomas. Patients with the aforementioned characteristics were significantly associated with tumor recurrence [11].


21.5.2 MIS Lateral Approach


Minimally invasive surgery (MIS) has been an emerging option in the management of degenerative spinal diseases to reduce postoperative comorbidities. There has also been more application of MIS in the management of oncological disorders of the spine, particularly in the thoracolumbar spine. Traditionally, open surgery for spinal tumors has been divided into anteriorly based or posteriorly based approaches, which are associated with different morbidities. Posterior approach-related morbidities include extended soft-tissue dissection resulting in excessive blood loss, a limited window to ventral lesions and constraints on vertebral body reconstruction and kyphotic correction. Anterior approach-related morbidities include a large incision for conventional thoracotomy, entry to the chest cavity, and pulmonary complications (such as atelectasis, pneumo- or hemothorax, pleural effusion). Also, most of spine surgeons are unfamiliar thoracoscope-combined techniques. On the other hand, the MIS lateral approach has been developed in order to reduce the abovementioned approach-related morbidities. For example, the MIS lateral approach to the thoracic and lumbar spine can minimize muscle destruction, blood loss, wound pain, and hospital stay, whereas it can still achieve complete tumor removal and reconstruction of spinal stability [75]. The advancement of tubular and expandable retractors, specialized instruments, and fiber-optic illuminations has helped the MIS lateral approach to prevail [59].

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Sep 23, 2017 | Posted by in NEUROLOGY | Comments Off on Neoplasia

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