Primary Spine Tumors: Diagnosis and Treatment

Michelle J. Clarke, MD; Ehud Mendel, MD; Frank D. Vrionis, MD, PhD

Disclosures

Cancer Control. 2014;21(2):114-123. 

In This Article

Diagnostic Imaging

Imaging studies remain the most important diagnostic modality in the face of a primary spinal column lesion. In many cases, due to the nonspecific presenting features, plain radiography is initially performed. Although radiography is an excellent screening tool, it should be noted that a negative radiograph is not definitive. Computed tomography (CT) provides superior information on cortical bone and tumor calcification, while magnetic resonance imaging is excellent at delineating soft tissue, paraspinal lesions, neural encroachment, bone marrow infiltration, and epidural extension.

In some cases, radiographic imaging can provide a definitive diagnosis. However, frequently imaging narrows the differential, supplying valuable information about the involvement and proximity of the tumor to neighboring structures. Although this may not be of definitive use from a diagnostic perspective, imaging suggests in many cases that a surgical approach will be required, and, prior to more invasive testing such as biopsy, it is reasonable to involve a surgeon in the patient's care at this point.

Depending on the differential diagnosis suggested by the imaging studies, it might be reasonable to begin the staging process, particularly in cases in which distant metastases are likely and may provide an easier biopsy target than with spinal imaging alone. In these cases, a technetium bone scan or positron emission tomography (PET) to look for metabolic activity in remote skeletal sites is a reasonable approach.

Biopsy

Lesional biopsy is often the most important step toward diagnosis, as well as a stumbling block of the treatment paradigm. Technical mistakes resulting in tumor spread may preclude complete resection in a potentially curable patient, thus a multidisciplinary approach that combines an experienced interventionalist in direct consultation with the surgeon responsible for potential resection is appropriate to avoid errors at this stage. Consideration for biopsy must be given to lesions that do not have a diagnostic appearance and harbor malignant characteristics such as bony destruction. More benign appearing lesions, particularly those in the posterior elements in younger patients, should be watched for signs of activity. Common primary tumor types are outlined in Table 2.

There are 4 main biopsy techniques: fine needle aspirate biopsy (FNAB), core needle biopsy, incisional biopsy, and excisional biopsy. In patients in whom results from imaging studies suggest a differential diagnosis that includes only benign lesions, excisional biopsy may be appropriate for both diagnosis and treatment. However, the likelihood of tumor disruption and local spread is high for both incisional and excisional biopsies, thus FNAB is recommended if the lesion is likely to harbor a malignant histology. Core needle biopsy allows the health care professional to obtain a column of tissue. It is a reasonable consideration if FNAB is nondiagnostic, although a higher likelihood of tumor spillage may exist and tract resection should be considered. To reduce the likelihood of tumor spread, sealing the biopsy site with bone wax or using the coaxial technique is recommended.[4]

Among the 4 techniques described above, CT-guided FNAB is the most common procedure, yielding a tissue diagnosis in 70% to 80% of procedures.[5,6] The procedure also has a low complication rate and a lower likelihood of an extralesional spread of tumor cells.[5,7,8] The importance of avoiding open biopsy cannot be overemphasized. In one series of patients with chordoma, 8% of the 25 patients undergoing FNAB followed by en bloc resection had a recurrence, yet 3 of the patients who underwent open biopsy (including 2 with subsequent en bloc resections) developed local tumor recurrence.[9]

Although the risk of tumor cell spillage is lessened by the FNAB approach, if possible, resection of the biopsy tract is still recommended. Thus, it is beneficial for the interventionalist and spine surgeon to discuss the likely surgical trajectory prior to biopsy. Along with selecting a trajectory easily incorporated into the planned surgical incision, marking the biopsy location is also helpful. Thus, in most cases, early referral to a tertiary center capable and with the appropriate surgical expertise is beneficial prior to biopsy despite diagnostic uncertainty.

Pathological diagnosis must involve a thorough review. If necessary, FNAB can be repeated to ensure adequate tissue for diagnosis. Because the diagnosis impacts treatment planning and prognosis, a second opinion is often encouraged. Primary tumors are very rare, so sending specimens to a recognized expert to confirm the diagnosis can be useful. In cases of typical or atypical hemangiomas, it is not uncommon for the biopsy results to be interpreted as normal bone marrow.

Metastatic Workup

Pathological diagnosis, in combination with the results of a thorough metastatic workup in malignant disease, dictates the treatment plan. Metastatic lesions at presentation alter the extent and type of therapy; for example, solitary lesions may undergo local treatment, while metastatic lesions necessitate a systemic approach to therapy. Evidence of metastasis also affects surgical decision-making. In patients without evidence of metastatic disease, aggressive en bloc resection of malignant lesions poorly responsive to adjuvant therapy may offer the opportunity of cure. Such a possibility is eliminated with evidence of metastatic lesions, changing the surgical plan from aggressive surgery with planned functional loss to a less aggressive debulking with preservation of function or completely forgoing resection.

The type of metastatic workup may be dictated by pathological diagnosis because specific pathologies have specific metastatic predilections. In many cases, PET is an excellent option, although a modification may be needed as it may predominantly provide information on the chest, abdomen, and pelvis. For instance, PET can stage angiosarcoma, which is a highly aggressive lesion, provided that complete limb imaging is included. CT of the chest, abdomen, and pelvis as well as bone scans are also appropriate options. In cases of suspected plasmacytoma or multiple myeloma, a skeletal survey, bone marrow biopsy, and immunoelectrophoresis are useful.

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