Laboratory Studies
For these patients, workup should include a complete blood count (CBC) and differential, a basic serum chemistry profile, erythrocyte sedimentation rate (ESR), or C-reactive protein (CRP) to help distinguish between neoplastic and infectious processes. Elevations in serum calcium or alkaline phosphatase (ALP) also can provide evidence for neoplastic bone processes. Specific studies, such as serum electrophoresis or urine electrophoresis, also can be performed to evaluate the likelihood of multiple myeloma or plasmacytoma.
Imaging Studies
Imaging studies for the workup of spine tumors include plain radiography, computed tomography (CT), magnetic resonance imaging (MRI), and technetium bone scanning. [9, 10, 11]
The first-line imaging study should be plain radiography to evaluate the trabecular architecture of the spine. Anteroposterior (AP), lateral, and oblique views may be required. These studies should be evaluated with respect to both what the tumor is doing to the bone and, conversely, what the bone is doing to the tumor. The blastic or lytic nature of the lesion should be noted. The general location of the lesion within the bone, the integrity of the cortex, and the presence of fractures or soft-tissue masses are important findings (see the images below).
Biopsy
The ultimate way of making the diagnosis and ascertaining the specific tumor type is to perform a biopsy of the spine lesion after all radiographic studies have been completed. Biopsies can be performed with open technique or percutaneous image-guided [12, 13, 14] technique. Percutaneous needle biopsies may not supply adequate tissue for the diagnosis of a primary tumor of the spine.
The basic principles of biopsy technique also apply to tumors of the spine. The surgeon performing the biopsy should take the most direct route to the tumor, with the least potential to contaminate adjacent compartments. The biopsy tract should be placed in line with the future incision site for surgical resection of the tumor, so that the biopsy tract can be excised with the specimen en bloc. (See the image below.)
Spinal tumors. Photograph of patient's back at time of surgery, exhibiting course of definitive incision to excise chondrosarcoma en bloc with previous biopsy tract included with resection.
Meticulous hemostasis must be obtained, and a drain must be placed to prevent hematoma formation, which can dissect the soft-tissue planes and contaminate adjacent compartments. The drain should exit the skin in line with the incision so that it, too, can be excised with the final specimen.
Histologic Findings
The histologic findings vary according to the tumor type, as described above. The following list revisits the primary tissue types associated with some of the tumors of the spine:
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Bone-producing tumors
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Cartilage-producing tumors
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Lymphoproliferative tumors
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Tumors of notochordal origin
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Round cell tumors
Bone-producing tumors of the spine include the following (see the images below):
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Osteoid osteoma - Benign and locally self-limited
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Osteoblastoma - Benign but locally expansile and aggressive
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Osteosarcoma - Malignant spindle cell lesion that produces osteoid
Cartilage-producing tumors of the spine include the following:
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Osteochondroma - Benign lesion with cartilaginous cap as described above
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Chondrosarcoma - Malignant cartilage producing tumors that histologically demonstrate round cellular stroma in a chondroid matrix (see the image below)
Lymphoproliferative tumors include the following:
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Multiple myeloma and plasmacytoma - Derived from plasma cell dyscrasias, which histologically appear as sheets of plasma cells
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Lymphoma - Associated with a large infiltrate of lymphoid cells
Chordoma is a tumor of notochordal origin that may be identified by the characteristic physaliferous cells (see the images below)
Spinal tumors. Higher magnification of chordoma histology demonstrates characteristic physaliferous cells.
Ewing sarcoma is a malignant round cell tumor of childhood that is associated with large sheets of homogenous small, round, blue cells.
Staging
Musculoskeletal tumors have typically been staged by using the Enneking system or its modifications—for example, the Musculoskeletal Tumor Society (MSTS) modification. [15] Tumors are separated first according to malignant potential (benign grades 1-3 or malignant grades I-III), then according to grade (low [I] vs high [II]), and finally according to location (intracompartmental vs extracompartmental or widely metastatic).
Spinal tumors specifically can be staged by using the Weinstein-Boriani-Biagini (WBB) system, which divides the vertebra into 12 sections in the axial plane in a manner resembling a clock face. This staging system is useful for the purposes of surgical planning. [16]
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Spinal tumors. Chordoma histology.
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Spinal tumors. Higher magnification of chordoma histology demonstrates characteristic physaliferous cells.
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Spinal tumors. Aneurysmal bone cyst histology.
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Spinal tumors. Coned-down view of lateral thoracic spine in patient with chondrosarcoma.
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Spinal tumors. Axial CT scan at level of chondrosarcoma seen on previous x-ray image.
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Spinal tumors. T2-weighted MRI scan of chondrosarcoma in same patient.
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Spinal tumors. Photograph of patient's back at time of surgery, exhibiting course of definitive incision to excise chondrosarcoma en bloc with previous biopsy tract included with resection.
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Spinal tumors. Histology of chondrosarcoma at 40 times magnification.
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Spinal tumors. Lateral cervical spine x-ray demonstrating osteoblastoma in posterior elements of C3 and C4.
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Spinal tumors. MRI of osteoblastoma in posterior elements of C3 and C4 seen on previous x-ray image.
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Spinal tumors. Histology of osteoblastoma at low magnification.
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Spinal tumors. Higher magnification of osteoblastoma.
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Spinal tumors. Coned-down view of hemangioma in thoracic spine.
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Spinal tumors. Axial CT scan of hemangioma in lumbar vertebra.
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Spinal tumors. Axial CT scan of thoracic vertebra, which demonstrates nidus of osteoid osteoma in posterior elements.
