The diagnosis of spinal tumors can be difficult. Unfortunately, in some cases the diagnosis is made late. Pain is most often the first symptom. Any case of pain along the spinal axis must be approached carefully, and the character of the pain should be thoroughly questioned in the differential diagnosis.
In the differential diagnosis of painful pathologies affecting spinal alignment:
• Spinal tumor
– History of malignancy, night pain
• Degenerative diseases
– Middle-aged patients
• Trauma
– Elderly patients with osteoporosis or a history of steroid use
• Infection
– History of fever, diabetes mellitus, IV drug use, chronic kidney disease, malignancy
• Rheumatologic diseases
– Polyarticular joint pain, morning stiffness
• Congenital (tethered cord syndrome, diastematomyelia)
Spinal tumors are divided into three groups according to their location in the spinal canal:
1. Extradural tumors (55%) originate outside the dura, from the vertebrae or epidural soft tissues. Metastatic tumors constitute the majority.
2. Intradural–extramedullary tumors (40%) arise from the leptomeninges or nerve roots.
3. Intramedullary tumors (5%) originate from the spinal cord itself.
PRIMARY SPINAL TUMORS
They account for 0.04% of all tumors and about 10% of all bone tumors.
General features
The patient’s age helps distinguish benign from malignant lesions. Benign tumors are more commonly seen in patients under 21 years of age, whereas malignant tumors (about 70%) are usually seen after the age of 21. The location of the tumor also helps in this distinction: malignant tumors most often involve the vertebral body, while benign tumors are more frequently localized to the posterior elements. Rapidly progressive neurological deficits are more commonly seen with malignant tumors.
The most common symptom is pain. Classically, the pain is more prominent at night. In some patients, both pain and deformity may be present, due to mechanical instability or paraspinal muscle spasm.
Neurological deficit is rarely the first symptom. However, at the time of diagnosis, about 70% of patients have some degree of weakness. Around 20% of patients show signs of spinal cord compression such as weakness, long-tract signs, and bowel or bladder dysfunction.
Physical examination and imaging
A detailed neurological examination (sensory loss, muscle strength, regional tenderness) provides information about the level of the lesion.
On plain radiographs, secondary findings such as destruction of the pedicle, loss of vertebral body height, or pathological fractures may be seen. The disadvantage of plain radiographs is their low sensitivity for detecting small tumors. Radiographic evidence of bone destruction is not apparent until 30–50% of the trabecular bone is lost.
CT is more sensitive and specific than plain radiographs. It more accurately defines the degree of bony destruction and plays an important role in preoperative planning for surgical stabilization or reconstruction.
Bone scintigraphy helps in differentiating tumor from infection.
MRI is the preferred modality for the diagnosis and evaluation of primary spinal tumors. Its advantages include excellent soft tissue contrast, multiplanar imaging, and the ability to assess neural compression or infiltration.
Imaging studies allow grading of the tumor. If imaging is insufficient to make a definitive diagnosis, biopsy is required. There are three types of biopsy: needle, incisional, and excisional. Needle biopsy is the least invasive and in most cases provides an adequate sample for diagnosis. Both incisional and excisional biopsy yield a definitive pathological diagnosis but are more invasive.
If tumor removal is necessary, the surgeon must choose the most appropriate approach for excision. Tumor excision is broadly classified as intralesional or en bloc. En bloc excision is the removal of the entire tumor in a single piece. If the surgeon cuts through the tumor mass, the excision is intralesional. If the tumor is dissected out along its pseudocapsule, this is termed marginal excision; if normal tissue surrounding the tumor is removed together with it, the procedure is considered wide excision.
BENIGN TUMORS OF THE SPINE
Benign spinal tumors are usually slow-growing, well-circumscribed lesions and are most commonly seen in younger age groups.
Osteochondroma
Solitary osteochondroma is one of the most common benign bone lesions and is frequently seen in young patients. Multiple osteochondromatosis is the most common form of skeletal dysplasia, and about 7% of these lesions occur in the spine. When neurological deficit is present, surgical resection is performed.
Osteoid osteoma and osteoblastoma
Osteoid osteoma and osteoblastoma are osteoblastic lesions that are distinguished by size. Lesions smaller than 2 cm are termed osteoid osteoma, whereas those larger than 2 cm are called osteoblastoma. These tumors are most common in the second and third decades of life and occur twice as often in men as in women. They frequently involve the posterior elements of the spine. The most common symptom is low back or back pain. Night pain is typical in osteoid osteoma, whereas it is less common in osteoblastoma. Characteristically, the pain is relieved by salicylates and nonsteroidal anti-inflammatory drugs (NSAIDs). In thoracic lesions, varying degrees of neurological deficit may be seen.
On imaging, osteoid osteoma appears as a nidus surrounded by dense sclerotic bone. Tumors growing close to the periosteum may cause fusiform expansion of the cortex due to hyperemia. Both the nidus and periosteal reaction may sometimes be seen on plain radiographs but are more easily visualized on CT. Bone scintigraphy and MRI help localize the lesion. On MRI, the lesion may appear larger due to surrounding hyperemia.
Osteoblastoma is usually easily detected on plain radiographs as a poorly marginated, expansile, radiolucent lesion that causes enlargement of the surrounding bone and may have a ground-glass appearance. CT may show marginal sclerosis and matrix calcification. The pedicle and posterior elements are more commonly involved. About 41–46% of all osteoblastomas are located in the spine, and 53% of spinal osteoblastomas are in the lumbar region. Scoliosis is seen in approximately 50–63% of patients with either osteoid osteoma or osteoblastoma.
Marginal excision is curative.
Aneurysmal bone cyst
Aneurysmal bone cysts are rare lesions. In 80% of patients, they occur under the age of 20. About 12–30% of all aneurysmal bone cysts are located in the spine, and 60% involve the posterior elements. The thoracic spine is most commonly affected. Pain is the most frequent symptom.
On plain radiographs, they typically appear as expansile, osteolytic cavities with a “soap bubble” appearance. They may sometimes lead to vertebral collapse. On CT, a very thin but continuous outer bone rim surrounding the lesion can be seen. Fluid–fluid levels can be visualized on both CT and MRI.
Radical resection provides local control.
Hemangioma
Hemangiomas are more common lesions, with an incidence of about 12%, and account for roughly 7% of all benign spinal tumors. They are usually asymptomatic but may rarely behave aggressively. They most commonly affect the lower thoracic and upper lumbar vertebrae.
On plain radiographs, they show the classic “striated” vertebral body appearance due to thickened vertical trabeculae. The lesion is easily recognized on CT. On MRI, it appears hyperintense on both T1- and T2-weighted images with contrast enhancement.
When symptomatic, treatment options include surgical excision or vertebroplasty.
Giant cell tumor
Giant cell tumors account for about 10% of all primary bone tumors. They are most common between the ages of 20 and 40 and occur predominantly in women (about 70.8%). Spinal involvement occurs in 3.2–6.5% of cases.
They are slow-growing but locally aggressive tumors. Pain is typically the first symptom. Neurological deficit is present in about one-third of patients. Most of these tumors involve the vertebral body; about 90% of cases occur in the sacrum. The thoracic, cervical, and lumbar vertebrae are less frequently affected.
On plain radiographs, they appear as lytic lesions with calcification and sclerosis. On MRI, they are hypo- or isointense on T1- and T2-weighted images, with prominent and heterogeneous contrast enhancement. Fluid–fluid levels may be present. Large tumors may cause pathological fractures and may have a soft-tissue component.
Marginal resection is required. Intralesional curettage carries a high local recurrence rate (25–50%). The risk of sarcomatous transformation after radiotherapy is around 10%.
Eosinophilic granuloma
Eosinophilic granuloma is a proliferative disorder of Langerhans cells, most commonly seen in children under 10 years of age. It is rare in adults and more frequent in males. Vertebral involvement occurs in 7–15% of cases. Sudden onset neck pain and torticollis are common presentations.
Radiologic appearance is variable. Early in the course, a centrally located lytic lesion is seen; later, vertebral body collapse and thinning of the vertebral body between intact adjacent discs (vertebra plana appearance) may be observed. Clinically, it is important to distinguish isolated lesions from systemic disease because the prognosis differs significantly.
Symptomatic lesions are treated with surgical excision.
MALIGNANT TUMORS OF THE SPINE
These are generally fast-growing lesions.
Multiple myeloma and solitary plasmacytoma
These tumors arise from plasma cells and are most frequently seen between 50 and 60 years of age, affecting both sexes equally.
Multiple myeloma is a multifocal plasma cell malignancy. The neoplastic cells produce complete or incomplete immunoglobulins. Its incidence is 2–3 per 100,000. Diagnosis is made by serum and urine protein electrophoresis. Serum protein electrophoresis shows an increase in one immunoglobulin type (IgG, IgA, rarely IgE or IgD). Urine protein electrophoresis detects Bence Jones proteins in 99% of cases