Keywords
spinal neoplasms/surgery - Ewing sarcoma/surgery - lumbar vertebrae - osteosarcoma/surgery
Introduction
Ewing sarcoma was first described by James Ewing in 1921, and is the second most frequent
malignant bone tumor in children, accounting for 3% of pediatric tumors and 10% of
primary bone tumors.[1] The tumor typically occurs in the long bones (more often in the femur) and pelvis.[2]
[3]
[4] Primary involvement of the spine is rare, with a reported incidence of 5% of all
primary sites.[2]
[3]
The most common symptoms of Ewing sarcoma are localized pain and neurological impairment,
ranging from radiculopathy to paraplegia.[1]
[5]
[6]
The imaging studies usually reveal aggressive vertebral body destruction, and most
patients present with an extraosseous soft tissue mass with direct invasion of adjacent
structures. Magnetic resonance imaging (MRI) is the method of choice for the detailed
study of paravertebral involvement.[1]
[5]
The surgical treatment is still challenging. En block resection is usually attempted,
and is directly related to the prognosis.[2]
[7]
Over the past three decades, the multidisciplinary approach and combined treatment
with chemotherapy and radiotherapy have contributed to an improvement in the survival
rates of the patients.[5]
[7]
Case Report
A 5-year-old girl was observed in the Pediatric Emergency Service due to low back
and abdominal pain, predominantly at night. Her symptoms had started one month prior
to admission, with progressive back pain exacerbated in the previous two weeks. The
pain did not respond to painkillers. The physical examination and the laboratory tests
were unremarkable.
A radiograph of the lumbar spine was performed on admission, and it revealed a lytic
lesion centered at L1 ([Fig. 1]). A subsequent MRI scan showed partial collapse of the L1 vertebral body due to
an infiltrative lesion predominantly involving the right posterior half of the vertebral
body and the ipsilateral pedicle, associated with a large extraosseous soft tissue
mass with intracanal extension ([Fig. 2]). The imaging features were consistent with an aggressive process. The patient was
submitted to a bone biopsy of L1, and, on the histological analysis, the morphological
and immunophenotypic characteristics were consistent with Ewing sarcoma/primitive
neuroectodermal tumor (PNET). A staging computed tomography (CT) scan did not reveal
distant metastases.
Fig. 1 The lumbar spine radiograph (anteroposterior and lateral views) that identified the
lytic lesion in L1.
Fig. 2 T2 contrast sequence of the magnetic resonance imaging scan of the lumbar spine.
L1 collapse by a lytic infiltrative component involving the right posterior half of
the vertebral body and the ipsilateral pedicle region, as well as marked intracanal
and extramedullary soft tissue components (Tomita et al.[12] type 4).
After chemotherapy according to the Euro Ewing protocol, the patient underwent surgical
treatment. A spondylectomy was performed in two stages under spinal cord neuromonitoring
through somatosensory and motor-evoked potentials. In the first part of the procedure,
we performed a pedicular fixation from D11-L3 and an excision of the posterior elements
and pedicles of L1 via a posterior approach. In the second stage, the anterior corpectomy
and reconstruction utilizing a Medtronic (Minneapolis, MN, US) cage filled with autologous
iliac graft were performed via an anterior approach ([Fig. 3]).
Fig. 3 Intraoperative pictures: left - after the spondylectomy; right - anterior reconstruction
with cage.
The patient was discharged 13 days postsurgery without neurological deficits. She continued
the adjuvant treatment with chemotherapy and radiotherapy for 6 months, according
to the protocol. On the first follow-up appointment, there was delayed healing of the
surgical wound with necrosis of the edges, with need of extended dressing care for
4 weeks. There were no complications with the instrumentation ([Fig. 4]).
Fig. 4 Lumbar spine radiograph (anteroposterior and lateral views) after one month of follow-up.
Over a three year period of follow-up, the patient had no restrictions regarding her
daily activities, and there has been no evidence of recurrence to date. A follow-up
CT scan revealed fusion of the instrumented levels ([Fig. 5]).
Fig. 5 Computed tomography scan 3 years postspondylectomy demonstrating bony growth through
the cage.
Discussion
The spine is often involved in cases of metastatic Ewing sarcoma. However, primary
Ewing sarcomas in the spine are rare.[4] The imaging findings vary, but a destructive lytic lesion with partial collapse of
the vertebral body is the most frequent presentation.[7]
[8] Systemic manifestations such as fever and weight loss, accompanied by an increase
in the total value of leucocytes and erythrocyte sedimentation, may be present.[1]
[7] Given the variability of imaging features and variable phenotype, the differential
diagnosis includes infection, neuroblastoma, eosinophilic granuloma and aneurysmal
bone cyst.[7] The MRI plays a key role in the evaluation of tumor extension and in the preoperative
planning.[1]
[4]
[8]
The treatment for Ewing Sarcoma is multidisciplinary. Most patients first diagnosed
with a local disease actually present later with systemic micrometastases, which emphasizes
the need for adjuvant treatment in all patients following local tumor surgical control.[1] Marco et al.[3] described a higher incidence of tumor recurrence and a lower survival rate in patients
treated only with chemotherapy and radiotherapy compared with results reported by
authors who performed the aggressive surgery. Therefore, aggressive surgical resection
appears to improve the prognosis.[3]
The Tomita et al.[12] classification, which is based on the anatomical location of tumors in the axial
and sagittal planes, is used as a guide for the surgical treatment. In the case described
here, the tumor was classified as type 4, and the indicated surgical treatment was
spondylectomy.[8]
There is still no consensus on the ideal method of local tumor control. Currently,
en bloc resection with negative margins is accepted as the ideal treatment for these
sarcomas, and is associated with an improvement in survival rates.[3]
[7]
[9] A systematic review published by Sciubba et al.[10] suggested that aggressive surgical resection was associated with improved overall
survival rate and local control.[10]
The aim of en bloc vertebral resection is to enable complete tumor resection with
free margins and decrease the likelihood of relapse.[5]
[11] Tomita et al.[12] did not report any local recurrence in a total of 23 patients who underwent vertebral
en bloc resection.[12]
Different techniques of en bloc resection have been described in the literature, such
as the posterior technique or the combined posterior and anterior approaches.[11] However, en bloc resection is not always possible because of the proximity of the
tumor to the neural structures.
In the current case, the authors preferred a two-stage approach. The posterior approach
enabled the stabilization of two vertebral levels above and below L1 with pedicular
screws, as well as the resection of the posterior elements of L1 with spinal decompression
and release of the D12 and L1 nerve roots. In the second stage, via an anterior approach,
the vertebral body and the remaining part of the pedicle were excised along with complete
D12-L1 and L1-L2 discectomies, with better local control of the adjacent great vessels
and viscera. This approach also enabled the reconstruction of the anterior column
using an expandable cage. In a biomechanical study, Oda et al.[13] described that posterior pedicular instrumentation associated with anterior reconstruction
with a cage provided the best stability after a spondylectomy.[13]
As a complication, our patient had necrosis of the surgical wound edges, which was
previously described by other authors.[11]
[14] Other frequent complications described in the literature include failure of the
metallic hardware, pseudarthrosis or infection.[11]
In conclusion, primary Ewing sarcoma in the spine is rare. The treatment of these
lesions remains a challenge, but tumor en bloc resection associated with an adjuvant
treatment with radiotherapy and chemotherapy is associated with a better prognosis.
