Overview: Spinal tumors occur predominantly in young or middle-aged adults and tend to be less common in children. The most common presentation is 3 to 6 months of pain, gait disturbance, change in spinal curvature, motor weakness, and bowel and bladder dysfunction. In the setting of acute trauma, peritumoral edema may cause paresis or paralysis. In this chapter, general concepts regarding spinal neoplasms will be discussed, followed by specific anatomic categories of lesions. Categories will include neoplasms located in the intramedullary, intradural extramedullary, or extradural compartments.¹

Imaging: The imaging features of spinal neoplasms are often nonspecific, and findings overlap. Familiarity with age at diagnosis, key imaging findings, and associations can narrow the differential diagnosis, as summarized in Table 45-1.

Although osseous spinal erosion can occur as a late finding with pediatric spinal cord tumors, plain radiographs are of limited utility. Unenhanced computed tomography (CT) is helpful in imaging primary osseous lesions, but it is not useful in cord evaluation. Instead, magnetic resonance imaging (MRI) is the study of choice to characterize and define spinal cord lesions. Differentiating intramedullary (within the cord) versus extramedullary (outside of the cord) location is important and can be accomplished with multiplanar MRI. Intramedullary lesions show cord expansion, whereas extramedullary lesions will be separate from the cord in at least one plane.

Intraoperative ultrasound may be used to determine tumor location and borders during exposure and resection. Baseline postoperative MRI is deferred for at least 12 weeks because surgical changes make early postoperative scans difficult to interpret.²

Treatment: The goal with benign, noninfiltrative spinal neoplasms is complete excision of both the solid tumor and associated syrinx cavities. If any portion of the neoplasm infiltrates the cord, surgical success decreases. Adjuvant radiation therapy and chemotherapy may be used, but the prognosis with an infiltrative, malignant lesion is dismal.³

Typically, a laminectomy is performed to gain access to the spinal cord lesion. Myelotomies are performed in the midline between the posterior columns or along the dorsal root entry zone. The tumor must be centrally debulked. Electrophysiologic monitoring techniques can be helpful as the periphery of the tumor is approached to prevent damage to the lateral columns of the spinal cord. The wound is closed when the tumor has been removed to its interface with normal-appearing spinal cord and the associated syrinx cavity has been carefully inspected for additional tumor deposits.³

Prognosis: Preoperative neurologic deficits may persist postoperatively, but most tumors can be removed without new long-term disabilities. If complete tumor excision is not possible with histologically benign pediatric intramedullary gliomas, adjuvant radiation therapy is preferentially avoided because of adverse effects on the immature spinal cord and spinal column. Residual and recurrent tumor deposits often remain static for years or grow very slowly. Symptomatic recurrences can be managed by operating again.

Surgical management is considered with extradural tumors to establish a pathologic diagnosis with biopsy, to decompress the spinal cord in the setting of progressive myelopathy, for reconstruction in cases of spinal instability, and with an attempted radical resection for cure. Most childhood spinal epidural lesions are responsive to radiation or chemotherapy.⁴

Overview: Pediatric intramedullary tumors occur most commonly in the cervicothoracic cord.⁵ Nonspecific symptoms often lead to a delay in diagnosis and vary with the age of the child. Younger children may present with spinal pain (dull and aching) or root pain, rigidity, persistent unexplained torticollis, and muscle spasm. Older children may present with gait disturbance and/or progressive scoliosis. Extremity weakness and paresthesias are common as well.⁶ A subset of patients may present with symptoms of increased intracranial pressure (ICP) and hydrocephalus.

Overview and Origin: Up to 60% of intramedullary tumors in children are astrocytomas, and the cervical cord is most commonly involved.³ Spinal astrocytomas usually occur in children around 10 years of age, with an equal sex predilection. Spinal astrocytomas are rarely seen in neonates and infants and may present with irritability, torticollis, and loss or absence of developmental milestones. Symptoms often are protracted.⁶ Astrocytomas arise from astrocytes and range from benign (grade I) to malignant (grade IV).⁷ Spongioblastomas and pilocytic astrocytomas are at the benign end of the spectrum, and high-grade astrocytomas and glioblastoma multiforme tumors are at the malignant end of the spectrum.

Spinal astrocytomas may be cystic, mixed cystic and solid, solid, or contain necrotic components. Malignant astrocytomas can mimic spinal vascular malformations as a result of hypervascularity with possible intratumoral hemorrhage. Lesion size varies from focal to involvement of the entire spinal cord (a holocord tumor), which usually is seen during the first year of life.⁸

Imaging: Contrast-enhanced spinal MRI is critical to the identification of small tumors with associated syringohydromyelia and to detect subarachnoid seeding. Key features of astrocytomas include cord expansion, eccentric location, hypointense to isointense appearance on T1-weighted imaging, heterogeneous hyperintensity on T2-weighted imaging, and variable enhancement, sometimes of a mural nodule, on postcontrast images (Figs. 45-1 and 45-2). T2 heterogeneity depends on the presence of solid, cystic, and necrotic components.⁵

Overview and Origin: Up to 30% of intramedullary tumors in children are ependymomas. Ependymomas present in an older age group than do astrocytomas (at age 13 or 14 years), with a slight female predilection.³ Ependymomas originate from ependymal cells within the central spinal cord or filum terminale, and they frequently span multiple segments. Holocord involvement, as with astrocytomas, is possible.⁹ A variety of histologic subtypes of ependymomas exist, with cellular ependymoma the most common. Myxopapillary ependymoma occurs exclusively in the lower cord and filum terminale. Surgical management of the myxopapillary subtype is difficult because of varied physical consistency of the lesion and relationship to surrounding structures. When occurring in the cauda equina, this subtype may be associated with subarachnoid hemorrhage, back pain, lower extremity weakness, numbness, pain, and even bowel and bladder incontinence.¹⁰

Imaging: Ependymomas are distinguished by the findings of central cord location, cord expansion, heterogeneous signal intensity on all sequences, and a T2 hypointense hemosiderin cap along the cranial or caudal aspects of the tumor (Figs. 45-3 and 45-4). Contrast-enhanced spinal MRI is useful in the evaluation of small drop metastasis, a common feature of ependymomas.^11,12 The presence of metastatic spread to the brain with resultant hydrocephalus can be evaluated with cranial MRI. Multiple ependymomas should prompt consideration of neurofibromatosis type 2 (NF2).¹³

Overview and Origin: Gangliogliomas contain both astrocytic and neuronal components. They present in the first three decades with an average presentation age of 12 years.5,14

Imaging: Gangliogliomas may be solid, cystic, calcified, or hemorrhagic. They demonstrate heterogeneous signal intensity on all sequences.¹⁵ Notable imaging features include a lack of peritumoral edema, even when large in size, and associated adjacent osseous erosion (Fig. 45-5). Given this lesion’s similar appearance to an ependymoma on MRI and its association with patients who have NF2, it should be included in the differential diagnosis when ependymoma is a diagnostic consideration.¹⁴

Overview and Origin: Hemangioblastomas are most commonly intramedullary, but they can be pial, subpial, or combined intramedullary-extramedullary.¹⁶ The presence of this lesion should prompt consideration of von Hippel–Lindau disease, and an appropriate workup should be initiated. Treatment includes chemotherapy and surgical resection.^17,18

Imaging: Hemangioblastomas frequently are cystic masses with variable T1 signal intensity depending on the proteinaceous content of the cyst fluid, T2 hyperintensity, variable enhancement of mural nodules, and a syrinx in up to 50% of patients (Fig. 45-6). Flow voids are produced by the arterial supply and draining veins of the lesion. Associated hemorrhage and peritumoral edema are common.¹⁹

Overview: Intradural-extramedullary spinal neoplasms in children include a variety of lesions such as neurofibromas/schwannomas, meningiomas, and leptomeningeal metastases.

Overview and Origin: The two main spinal nerve sheath tumors are neurofibromas and schwannomas, with the focus in this chapter on neurofibromas.²⁰ Neurofibromas may be derived from an intermediate cell or from a combination of Schwann cells and perineural fibroblasts. Most spinal neurofibromas are intradural-extramedullary lesions. The two morphologic types are fusiform (arising from a single nerve fascicle) and plexiform (involving multiple nerve branches). The lesions may be single, multiple, or diffuse. Neurofibromas usually are encountered in children with neurofibromatosis type 1 (NF1), but they may occur as an isolated lesion.²¹

Imaging: Neurofibromas have a variable T1 signal, are T2 hyperintense, and enhance after administration of contrast material. Diffuse neurofibromas may extend along the paraspinal region. Key imaging features of neurofibromas include remodeling and expansion of the intervertebral foramina, which is indicative of slow indolent growth, and a target appearance (central low signal with peripheral high signal) on T2-weighted images (Fig. 45-7). Rib erosion may be seen, and when it is severe over a long length of the rib, it may cause “ribbon ribs.” Malignant degeneration into a neurofibrosarcoma is uncommon but should be considered in large lesions with bone destruction or necrosis.

Overview and Imaging: Meningiomas of the spinal cord are rare in childhood.²² When they are seen in patients with NF2, they may occur intracranially and intraspinally. Meningiomas are T1 hypointense to isointense, T2 hyperintense, and uniformly enhance after administration of contrast material (Fig. 45-8). Areas of hypointensity may be due to calcification.²³

Overview and Origin: Metastatic spread to the spinal canal most commonly occurs via the cerebrospinal fluid (CSF) as a result of drop metastases from primary supratentorial and posterior fossa brain neoplasms, such as medulloblastoma, ependymoma, and atypical teratoid-rhabdoid tumors.²⁴

Imaging: CSF metastases may be solitary, multiple, or diffuse, coating the spinal cord and nerve roots. Metastatic nodules may range in size from 1 to 2 mm to 1 to 2 cm and may block CSF flow (Fig. 45-9). The most common site is the distal thecal sac in the lumbosacral area, followed by the thoracic, and finally the cervical spine.²² To avoid false-positive MRI examinations, the spinal cord should be scanned before surgery for newly diagnosed brain tumors with a propensity to spread via the CSF. If preoperative MRI is not feasible, MRI should be delayed for 4 to 6 weeks after surgery to avoid confusion and possible false positve results.¹¹

Overview: Most childhood extradural neoplasms arise in the vertebral bodies or the paravertebral soft tissues and invade the spinal canal via the intervertebral foramina, such as neuroblastomas and sacrococcygeal teratomas. Primary osseous lesions, such as aneurysmal bone cysts, lymphoma, and Ewing sarcoma, as well as metastatic lesions, also may involve the vertebra and, secondarily, the spinal canal. Imaging is used to determine the extent of spinal involvement, the degree of neural element compression, and the degree of destabilization of the spinal column by destruction of osseous elements.12,25

Overview and Origin: Tumors of neural crest cell origin include neuroblastomas, ganglioneuroblastomas, and ganglioneuromas. Neuroblastoma is by far the most common extracranial solid neoplasm, usually presenting between 1 and 5 years of age. Neuroblastomas are classified as primitive neuroectodermal tumors (PNETs) when they involve the central nervous system.

Neuroblastomas originate from neuroblasts along the sympathetic chain and arise most commonly from the adrenal gland. Metastatic involvement of the spine can be to bone or sympathetic chain ganglia, may be single or multilevel, or may extend into the epidural space with spinal cord compression. Larger lesions may have areas of hemorrhage and necrosis. Metastatic involvement of bone, bone marrow, liver, lymph nodes, and skin can be present. Ganglioneuroblastoma and ganglioneuroma are progressively less malignant forms of neuroblastoma that are composed of a mixture of mature ganglion cells and nerve fibers. They usually are well encapsulated and have a similar imaging appearance to neuroblastoma, although they are smaller and better defined.

Imaging: Neuroblastomas are paraspinal soft tissue masses, often with intraspinal extension. The lesion is hypointense to isointense on T1-weighted imaging compared with the spinal cord, demonstrates subtle hyperintensity on T2-weighted imaging, and has variable enhancement after administration of contrast material (Fig. 45-10). Hypointense areas on T1- and T2-weighted imaging may indicate calcifications. Fat-suppressed T2-weighted imaging is important to determine the extent of disease. Imaging to evaluate for extension across the midline is important in staging.¹

Overview and Origin: Sacrococcygeal teratomas (SCTs) are neoplasms derived from all three germinal layers. These neoplasms may contain neural elements, squamous and intestinal epithelium, skin appendages, teeth, and calcium. Four types of SCTs are found; type 1 is external, type 2 is predominantly external with a small intrapelvic portion, type 3 is predominantly intrapelvic with a small external component, and type 4 is completely intrapelvic. All four types may present as an extradural mass and may be associated with sacrococcygeal bony erosions. SCTs can be cystic, mixed cystic-solid, or solid lesions. Lesions are more likely to have a favorable prognosis in younger patients, in female patients, when they are mostly cystic masses, when they are less heterogeneous masses, when more calcifications are present, and when they are type 1 (external). SCTs may be benign or malignant.

Imaging: CT is used to demonstrate osseous destruction of the sacrum and coccyx, as well as calcification within the lesion. Cystic components of SCT are T1 hypointense and T2 hyperintense. The MR signal of hemorrhagic components will depend on the age of the hemorrhage. Solid components may enhance after administration of contrast material (Fig. 45-11).

The location of the SCT in relationship to the gluteal fold helps to differentiate this lesion from back masses associated with spinal dysraphic conditions. Specifically, SCTs typically extend below the gluteal fold, and masses associated with spinal dysraphism typically extend above the gluteal fold.²⁶

Overview and Origin: Lymphoma involves the spine less commonly than it does other reticuloendothelial system structures, such as lymph nodes. Single or multiple vertebral bodies may be involved, especially with non-Hodgkin type lymphoma (Fig. 45-12). A diffuse dural infiltration, a localized dural-based mass, a primary osseous mass with spinal canal extension, or spinal cord masses may be present. Single or multiple vertebral levels may be involved. Epidural deposits from leukemia more commonly produce clinical symptoms in children than in adults, with myelogenous leukemia more likely presenting as a focal mass (Fig. 45-13).²⁷

Imaging: Epidural involvement in patients with lymphoma and leukemia is usually isointense on noncontrast T1-weighted imaging. Homogeneous enhancement is seen after administration of contrast material. A key imaging feature suggesting lymphoma or a myelogenous leukemic mass is slightly low signal on T2-weighted images, along with lack of vertebral compression or other osseous destruction.²⁸

Overview: Neurocutaneous melanosis is a rare, nonfamilial phakomatosis caused by melanocyte proliferation within the epidermis and leptomeninges. It is a nonfamilial disease characterized by large cutaneous pigmented nevi and melanosis of the leptomeninges. A forme fruste may occur in which only leptomeningeal involvement is present without cutaneous manifestations. In the pediatric population, leptomeningeal involvement may present with signs of raised ICP and hydrocephalus.

Imaging: The most common appearance is diffuse leptomeningeal thickening and enhancement after administration of contrast material, as can be seen with leptomeningeal metastases. Although leptomeningeal metastatic disease is more common than leptomeningeal melanosis, the presence of melanin, which is seen as hyperintense signal on noncontrast T1-weighted images, should prompt consideration of this disease (Fig. 45-14). T1 hyperintense melanin deposits most commonly involve the hippocampus and brainstem.²⁹

Overview: Numerous vertebral osseous abnormalities may extend outside of the spine and produce extradural mass effect. Lesions in the spine tend to arise either from the posterior elements or the vertebral body. Common posterior element lesions include osteoid osteomas, aneurysmal bone cysts, and osteoblastomas. Common primary pediatric vertebral masses include Ewing sarcoma, lymphoma, Langerhans cell histiocytosis, and metastatic disease such as neuroblastoma, leukemia, and PNET.

Imaging: The imaging appearance of extradural bony masses varies depending on the specific type of lesion. Unlike with most spinal tumors, CT plays a greater role in the imaging of osseous masses and neoplasms and is complimentary to MRI. Posterior element lesions, which include osteoid osteomas, have a focal sclerotic nidus surrounded by a lucent halo on CT and show a “double density sign” on nuclear bone scintigraphy. On MRI, these lesions show impressive surrounding edema. Aneurysmal bone cysts classically appear as an expansile, multilocular lesion with fluid-fluid levels due to internal hemorrhage and debris (Fig. 45-15). Osteoblastomas are expansile solid masses of the posterior elements and rarely have internal fluid levels (Fig. 45-16). Focal vertebral body lesions, as may be seen with Ewing sarcoma and lymphoma, tend to cause T1 hypointense, T2 hyperintense marrow signal with enhancement after administration of contrast material in a single vertebra with little loss of vertebral body height. Similar features are less often seen with multiple vertebral body involvement.³⁰