Relevant Primary Spine Tumors

1. Hemangioma

Hemangiomas are benign intraosseous vascular lesions involving the vertebral body. They represent 30% of primary spinal tumors.¹ These lesions are often diagnosed incidentally.¹² In up to 11% of autopsies, spinal hemangiomas are incidentally found.13,14 These lesions are seen in the fourth to sixth decades of life and are usually asymptomatic.1,13 On CT imaging, these lesions often have a salt-and-pepper appearance.12 They are hyperintense on both T1 and T2 sequences of the MRI.12 However, spinal hemangiomas can cause focal pain and tenderness, for which medical management is recommended.13,14 Other options include kyhoplasty, vertebroplasty, and transarterial embolization.13 In patients with neurological compromise, often an intralesional or en bloc resection with stabilization surgery may be necessary.15 2. Aneurysmal Bone Cysts

Aneurysmal bone cysts (ABCs) were first described in 1943 by Jaffe and Lichetenstein[A1].16 These lesions are expansile tumors that contain thin-walled, blood-filled cystic cavities.13 These lesions represent up to 10% of primary spinal tumors.1,17 Most lesions are diagnosed within the thoracic or lumbar spine in the first three decades of life.13,18 On CT/MRI, ABCs are cystic and lytic lesions with fluid-fluid levels.1 ABCs usually arise from the posterior elements but often invade the epidural space and pedicles, which can lead to neurological compromise and mechanical instability.18 Most ABCs grow over time.13,18 Various treatment options, including simple curettage, complete excision, radiotherapy, and embolization, are available.13,16,18 There has yet to be a consensus on optimal management of spinal ABCs. An actual en bloc resection with the ABC in one piece with a broader layer of normal tissue surrounding is challenging to achieve in aneurysmal bone cysts due to its characteristic profile.18 An intralesional piecemeal resection with bone grafting is often the surgical treatment for ABCs.13 Boriani et al showed that complete intralesional resection without any adjuvant radiation had no recurrences.19 However, partial intralesional resection is associated with high local recurrence rate. Studies by de Kleuever et al and Hay et al showed a 25% local disease progression.20,21 The majority of the recurrences occur within the first 6 to 12 months.18 Harrop et al recommend complete intralesional resection of ABCs due to incomplete removal's high local recurrence rate.18 Embolization of ABCs is associated with decreased intraoperative bleeding.13,22 A few case reports have been published supporting the isolated use of transarterial embolization to treat ABCs.19 Transarterial embolization should be considered in patients with recurrent ABCs or who cannot undergo surgery. Embolization requires a prolonged follow-up to assess the treatment outcome.18,19 Of note, risks of transarterial embolization include ischemic injury to the spinal cord and brainstem.18,23 Finally, met with megavoltage radiotherapy with 26-30 Gy for recurrent or inoperable ABCs has been shown to have up to 75% local control rates.13,24 Of note, given that the majority of the ABC patients are young, the risks associated with the treatment of radiotherapy must be carefully considered. Ideally the preferred treatment is a complete intralesional resection. 3. Osteoid Osteoma and Osteoblastoma

Osteoid osteomas and osteoblastomas are bone-forming lesions that produce osteoid and woven bone, and are often seen in long bones.12 These lesions, however, can also occur in the spine; they represent 10% of primary spinal tumors.1,12,18 Osteoid osteomas are four times more common than osteoblastomas.1,13,18 At the time of presentation, most patients are in their first decades of life, and CT shows a sclerotic nidus.1 Osteoid osteoma and osteoblastomas are often found in the posterior elements of the spine, but osteoblastomas might extend into the anterior column.18 Back or neck pain that worsens at night is the most common presenting symptom.13,25 Nonsteroidal anti-inflammatory drugs often resolve the pain associated with osteoid osteoma.12,13 Another symptom associated with osteoblastoma is painful scoliosis, seen in 25-62% of patients.13,25 Treatment options for these lesions include medications, surgical resection, CT-guided laser thermocoagulation and radiofrequency ablations, and radiotherapy.13,26 While most osteoid osteomas can be managed with medical management or percutaneous treatment options, osteoblastomas often require surgical intervention, as they are more aggressive, have a higher recurrence rate, and higher potential malignant transformation.18,27 Zileli et al and Flemming et al found up to 50% recurrence rates in patients with subtotal resection of osteoblastomas.28,29 Given the high recurrence rate, en bloc resection is recommended for aggressive osteoblastomas of Enneking grade 3.18 Radiation treatment after incomplete osteoblastoma resection has not been effective in preventing recurrences.18 Additionally, chemotherapy has a minimal role in the management of osteoblastomas.13,30 Other CT-guided therapies are more suited for the management of osteomas, with CT-guided thermocoagulation having a 94% success rate.13,26 4. Chordoma

Chordoma is a slow-growing tumor originating from embryonic remnants of the notochord.12,13 Chordomas represent 4% of primary spinal tumors.1 These lesions can occur anywhere along the spinal column but are most often seen in the clivus and the sacrum.12,31 These lesions are often seen in patients in their fourth through sixth decades.1 Chordomas are more prevalent in men than women, with a 2:1 ratio.2 CT shows expansile lysis and sclerosis, while MRI shows T1 hypointensity and T2 hyperintensity with irregular contrast enhancement.2 Thirty percent of sacral chordomas progress to metastasized.32 Mukherjee et al reviewed 414 patients with chordomas. They reported a median survival of 50 months with 5-year survival of 62%.33 In comparison, 5-year survival is only 18% in patients diagnosed with osteosarcoma.33

An en bloc resection of spinal chordoma is critical in improving local recurrence rates and survival. Gokaslan et al reviewed 166 patients with spinal chordomas in the spine. They found that patients who underwent Enneking inappropriate resections had a seven times higher chance of having local recurrence compared to patients who underwent Enneking appropriate resections.35 However, attaining an en bloc resection is difficult in chordoma surgery as these lesions are slow growing and poorly develop into large tumors before diagnosis. Additionally, obtaining a wide resection with normal tissue along the surgical specimen has potential to result in considerable morbidity given the proximity of the neural elements.13 Radiation therapy has been used as an adjunct in the management of spinal chordomas. Curative dosing for chordomas at about 70Gy is higher than the tolerant dose of the spinal cord at 50Gy.13 Various strategies have been closed, including proton beam and carbon ion treatment given conventionally.35,36 Recently, a high dose single fraction radiosurgery of 24Gy given neoadjuvant or postoperatively associated with high success rates—96.3% and 89.9% local recurrence-free survival and 90% and 84.3% overall survival at 3- and 5-year periods, respectively.37