Benign tumors are divided into three stages. First stage tumors (S1) are “latent” tumors which are inactive and usually asymptomatic. Their feature is to be surrounded by a true capsule, expression of latency. Once identified as latent tumors, these do not need to be submitted to a treatment based on oncological principles as they tend to grow very slowly if at all. Intraosseous enchondromas, osteochondromas, hemangiomas, or lipomas (extremely rare) can be staged into this category. Palliative surgery is required for spinal cord compression or spinal instability due to pathologic fractures, while in most cases these tumors must be followed with clinical and imaging observation.

Second stage (S2) “active” benign tumors tend to grow at a certain rate albeit slowly and often become symptomatic. These are surrounded by a thin layer of fibrous capsule and induce the formation of a reactive inflammatory tissue, which may be seen on MRI (“pseudocapsule”). Oncologic treatment of S2 tumors consists of surgical excision. Embolization, cryotherapy, and radiofrequency ablation are other modalities that may be used in conjunction with surgery or alone.

Third stage (S3) benign tumors (“aggressive”) are rapidly growing tumors with a very thin or absent capsule. These tumors invade the neighboring compartments and usually have a wide reactive hypervascularized “pseudocapsule.” They usually grow to become large enough to be visible on radiographs, technetium bone scans are usually significantly positive, and CT and MRI demonstrates the aggressive nature of the tumor. Treatment consists of surgical excision of adequate aggressiveness along with the help of one or more of the surgical adjuvants delineated above.

Malignant tumors are studied based on the concept of “grade” and classified into two groups as low grade and high grade. These are further subdivided into two categories of A and B based on the relation of the tumor with the compartment it has originated from. A is used for the tumors that are still within the compartment at the time of diagnosis, and B for those that have extended beyond that compartment or has originated at a location with no natural boundaries and therefore does not constitute a compartment (e.g., intrapelvic). Based on this, a low-grade stage IA tumor is one that remains inside the vertebra itself and by contrast, a stage IB tumor invades paravertebral compartments. These tumors usually have thick pseudocapsules of reactive tissue and small, microscopic tumor islands within that reactive zone called “satellite nodes.” The acceptable resection margin is therefore wide resection if possible. High-grade tumors are likewise divided into stages IIA and IIB. These are very rapidly growing tumors with no reactive tissue; on the other hand they do have not only satellites lesions but also a significant risk of skip metastases (foci of tumor outside the main mass, completely isolated). High-grade tumors are identifiable on plain radiographs, but MRI is needed in addition to show the entire extension of the tumor and the absence of reactive zone. Treatment is wide en bloc excision as radical excision in the spinal column is impossible [16].

After the definitive diagnosis and oncological staging has been established, the next step before biopsy should be surgical staging. The most widely used scheme was developed by Weinstein for primary spine tumors and later modified by Boriani and coworkers to become the WBB (Weinstein, Boriani, Biagini) system [17]. This system is useful for defining the local extent of the tumor and therefore eventually dictates the type of resection needed. Vertebra is divided into 12 radiating zones in a clockwise order (from 1 to 12), five concentric layers from paravertebral extraosseous to the intradural region (A to E) (Fig. 25.1), and the longitudinal extension of tumor as expressed by the number of involved spinal segments is added as a separate parameter. The major advantage of this system is that it delineates the relation of the lesion with the spinal cord and therefore intrinsically marks out the amenability of the tumor to wide resection. These authors recommend that in order not to endanger the spinal cord and to control the epidural space, the surgeon should aim to resect wedge sectors of the vertebra [16].

Another classification system is proposed by Tomita and coworkers. This system is composed of a two-part numeric system and incorporates a detonation of tumor location providing a simplified scheme for describing the extent of vertebral involvement. The first numeric part describes the affected anatomic site, comprising 1 vertebral body, 2 pedicles, 3 lamina, transverse and spinous processes, 4 spinal canal, and 5 paravertebral area. The second numeric part describes tumor extension in numbers ranges from 1 to 7. These authors tended to consider type 1, 2, and 3 lesions as intracompartmental, type 4, 5, and 6 lesions as extracompartmental, and a type 7 lesion as a multisegmental tumor or one with multiple-skip lesions [18]. For the sake of simplicity only the WBB system will be used in this text.

Biopsy is an essential step before planning the treatment. The purpose of this procedure is to provide the pathologist with an amount of pathological tissue both quantitatively and qualitatively representative for diagnosis. Its volume must be adequate for different staining and for immunohistochemical studies. The tissue must not be removed from necrotic, reactive, or fibrotic areas; it must be taken from the core of the vital tumor. Biopsy is by definition an intralesional procedure and therefore includes the high risk of spreading tumor cells in the surrounding tissue, with the obvious consequence of increasing the risk of local recurrence. The most important surgical principle is to include the biopsy route within the line of incision that will be used at the time of definitive surgery, particularly in case of en bloc resection, whose specimen will necessarily include the entire biopsy tract from the skin to the tumor mass. For this reason, the biopsy approach should never be performed along the anatomical extracompartmental spaces, as performed in elective non-oncologic orthopedic surgeries. The biopsy approach must always be performed inside muscles, in order to make easier the removal of the tract. Following these principles, biopsy can be performed through percutaneous or open techniques [19]. Open biopsy should be performed by the surgeon who will perform the definitive surgery; it may result in substantial blood loss and morbidity, but the surgeon can obtain a relatively large amount of tissue for diagnosis decreasing the likelihood of a sampling error. A particular care should be adopted to control bleeding and avoid hematoma, which is a severe complication of biopsy as the tumor cells can be seeded on a wide area, almost impossible to resect later on.

Percutaneous biopsy (performed by fine core needle or best by a trocar) is a relatively simple procedure and has been proven to be safe and effective when performed under CT-scan image guidance [20]. On the other hand, selection of the optimal biopsy technique depends on the differential diagnosis, the location and extension of the lesion, and the potential definitive treatment plan. Although there is the theoretical possibility of having intraoperative frozen sections, the present authors do not recommend it on a routine basis as in our hands it has been associated with a substantial rate of diagnostic errors, totally unacceptable for tumor surgery in spinal column. Therefore it should be reserved for cases whose imaging is pathognomonic (like some ABC or some OO) or for the confirmation of the adequacy of surgical margins if necessary. Open biopsy should be avoided when a malignant bone tumor is suspected on clinical and imaging studies due to the highest risk local recurrence. Transpedicular image-guided trocar biopsy allow to remove adequate sample from anterior elements without contaminating the thoracic or abdominal cavities; to reduce the risk of seeding from the empty pedicle, it can be filled with acrylic cement [16].

The goal of the surgery for pediatric spinal primary tumors is to allow the best local and systemic control; conversely, the treatment of metastatic and systemic diseases is mostly palliative, aiming at pain relief, decompression of neural structures, provide correct alignment, stability, and possibly mobility to the spine [21].

Tumor removal in case of metastatic and systemic disease is reasonable if the specific tumor type has low sensitivity to chemotherapy and radiation therapy.

A commonly accepted terminology for surgical procedures and for definition of tumor extent is needed for surgical planning. Lesions in the pediatric spine are often more challenging to treat than lesions of similar behavior elsewhere in the musculoskeletal system. “Curettage” describes the piecemeal removal of the tumor. As such, it is always an intralesional procedure. “En bloc” indicates an attempt to remove the whole tumor in one piece, together with a layer of healthy tissue. The term “intralesional” is appropriate if the surgeon has been within the tumor mass at any time during surgery; “marginal” is appropriate if the surgeon has dissected along the pseudocapsule, the layer of reactive tissue around the tumor; and “wide” is appropriate if ablation could be performed outside the pseudocapsule, removing the tumor with an undisturbed shell of healthy tissue. This wide en bloc procedure can be called “excision” or “resection.” “Radical resection” means the en bloc removal of the tumor and the whole compartment of tumor origin which is virtually impossible for a spine tumor because of the ring shape of the vertebral body around the neural structures and also because of the fact that some compartments such as the epidural or subdural spaces extend from sacrum to cranium [16]. Slow-growing but locally aggressive primary tumors that may be easily treated elsewhere in the skeleton may be unresectable and potentially lethal in certain locations in the spine. The surgical approach should be planned carefully and must achieve the prescribed appropriate margins. While intralesional removal may be associated with excellent outcomes for many patients with benign latent tumors and benign active tumors, more aggressive surgery is indicated for some locally aggressive benign tumors and many malignant tumors. Non-metastatic malignant tumors are ideally removed with wide surgical margins, when technically feasible.

As described above, the treatment depends on diagnosis, natural history, location, size of the lesion, as standardized in the Surgical Staging System (SSS) which dictates the type of surgical treatment to be used. Benign latent lesions (S1) do not require oncologic treatment as they are latent. Benign active tumors (S2) do have growth potential: Intralesional excision usually can be performed with a low rate of recurrence. Benign aggressive tumors (S3) infiltrate neighboring compartments and have wide reactive hypervascularized pseudocapsules. En bloc resection with wide/marginal margins is often indicated for reasonably acceptable recurrence rates when possible. If not, intralesional excision and additional local adjuvant therapies such as phenol or alcohol administration, cryotherapy with liquid nitrogen or abundant use of polymethylmethacrylate (PMMA) may be necessary. Depending on specific sensitivity, radiation therapy can be helpful as an adjuvant. The side effect of radiation therapy on growing bone must be considered, together with the risk of secondary radio-induced tumor in patients with a long life expectancy [22].

Management of malignant spinal tumors is more complex and requires a multidisciplinary approach. Early detection of the tumor followed by complete excision is advisable [18]. Again the SSS helps to delineate the progressive stages of a given tumor and the specific implications for surgical treatment and provides guidelines for the use of adjuvant therapy. Advances in chemotherapy and techniques for resection and reconstruction have expanded the role of local surgical management. For optimal surgical treatment oncological staging of lesion is essential. The grade of the tumor as a sign of the general behavior, presence of metastatic lesions, location and extension of the tumor in the spinal column are important factors. Local control of the malignant pediatric spinal tumor can only be achieved with a well-planned wide resection. However, wide en bloc excision procedure may be impossible in some cases because of the location and the extent of the tumor. Even if the spinal cord and nerve roots are sectioned above and below, the epidural space represents a compartment extending from the skull to the coccyx. Therefore, a tumor-free margin en bloc resection is not possible when a stage II malignant tumor is encroaching the canal.

Three different en bloc resection surgeries have been defined: vertebrectomy, sagittal resection, and resection of the posterior arch. Vertebrectomy implies removal of all the elements of the vertebra, which may be total, or hemi- in the sagittal plane. These procedures can be performed in staged, sequential, or simultaneous anterior and posterior approaches or in a single stage through posterior approach [18, 23–26]. Lesions involving the posterior elements of the spine are obviously submitted to en bloc excision by posterior approach [16].

Reconstruction of the spine after resection before maturity requires a further concern as long fusions can be followed by secondary impairment of sagittal balance, while short fusions – particularly if associated with muscle and ligament sacrifice as required in tumor resection – can create shortly a segmental instability [27].