Lumbar Ewing’s Sarcoma Mimicking a Herniated Disc in a Young Adult: A Case Report

Introduction

Ewing’s sarcoma is typically defined as a bone malignancy. It was first described in a 14-year-old girl by James Ewing in 1921, dubbing it a “diffuse endothelioma of bone” and on becoming his eponym.¹ Although uncommon in childhood and adolescence, it is still the second most common malignant bone tumor in children and adolescents after osteosarcoma, and occurs less frequently in older age groups, rarely occurring beyond the age of adolescence.^2–5 Despite its typical detection in the pelvis and long bones, Ewing’s sarcoma has also been described and diagnosed in a variety of other locations in the body, such as the spine, skull, clavicle, scapula and hands and feet, albeit much less commonly.⁶ The number of cases of spinal Ewing’s sarcoma in the young adult population published in the literature is rare, especially in the lumbar spine.^6,7 Patients usually present with nonspecific symptoms of lower back pain accompanied with possible numbness or weakness of the lower limbs or even cauda equina in some occasions.⁸ This symptomatology mimics that of diseases such as disc herniation, degenerative disc disease, infections or nerve sheath pathologies, leading to a higher rate of misdiagnosis and diagnostic delays in these patients.⁹

Here, we present the case of a 23-year-old male patient presenting to our clinic with a lumbar spine Ewing’s sarcoma misdiagnosed as a herniated lumbar spine disc. While a herniated disc typically presents as a focal intervertebral disc abnormality without aggressive bony changes, spinal Ewing’s sarcoma commonly presents on magnetic resonance imaging (MRI) as an enhancing vertebral or extradural mass involving bone destruction and significant soft-tissue extension.^9–12

Case Presentation

A 23-year-old male patient presented to our clinic with a few weeks’ history of progressive lower back pain radiating to his lower extremities bilaterally. He also reported a subjective weakness of both lower extremities in dorsiflexion of the ankle and great toe as compared to his other lower limb that appeared on follow-up a couple of weeks after his pain sensation had initiated. He had been evaluated at a different facility previously, and no earlier MRI studies were available prior to this presentation. An initial magnetic resonance imaging scan (Figure 1) was performed revealing an L5-S1 mass, lying posterior to the L5 vertebral body, compressing the spinal cord that had been diagnosed as a herniated disc by the radiologist and surgeon at the outside institution. He was first placed on conservative medical treatment, but after he started to develop subjective weakness, he was referred for surgical treatment and decided to seek a second opinion.

Figure 1 (A) T1 weighted axial lumbar spine MRI cut showing the tumor behind the L5 body with tissue seemingly invading into the posterior wall of the vertebral body and eroding it. (B) T1 weighted sagittal lumbar spine MRI cut showing the same findings. (C) T2 weighted axial lumbar spine MRI cut showing the tumor behind the L5 body with tissue seemingly invading into the posterior wall of the vertebral body and eroding it. (D) T2 weighted sagittal lumbar spine MRI cut showing the same findings.

Upon presentation to our facility, clinical examination revealed an active young male patient that is in good shape and that had a normal general physical examination. He had no history of any previous medical problems since childhood and was up to date on all his medical check-ups. He had tenderness over the paraspinal area of his lower back. Neurological examination demonstrated bilateral L5 weakness (ankle and great toe dorsiflexion 4/5 MRC), reduced sensation over the dorsum of both feet, diminished ankle reflexes, positive straight-leg raise at 40 degrees bilaterally, intact perineal sensation, and preserved bowel and bladder control.

Surprisingly, the assessment of the previously done MRI of the lumbar spine (Figure 1) by the physicians at the initial facility was reported by the patient as a centrally herniated L5-S1 disc compressing the neural elements. After studying the MRI and suspecting a tumorous lesion rather than a herniated disc, our team ordered a CT scan of the lumbar spine (Figure 2) revealing some lytic lesions at the posterior wall of the L5 vertebral body. An associated soft-tissue mass was noted. We then referred the patient to the interventional radiology team for a possible biopsy and histopathological assessment; however, the CT guided biopsy could not be performed. A decision was then taken to perform open surgical decompression of the mass and to refer samples for further histopathological evaluation.

Figure 2 (A) Sagittal cut of a CT scan of the lumbar spine showing lytic lesions of the posterior wall of the L5 vertebral body. (B) Bone window sagittal cut of a CT scan of the lumbar spine showing lytic lesions of the posterior wall of the L5 vertebral body. (C and D) Bone window axial cut of a CT scan of the lumbar spine showing lytic lesions of the posterior wall of the L5 vertebral body.

Surgical Treatment

The patient underwent an open L5-S1 laminectomy without instrumentation. Decompression of the nerve roots bilaterally with attempted gross total resection was performed. En-bloc resection was not feasible due to anatomical constraints. Curettage and debridement of the posterior L5 vertebral wall and bone elements was performed. No gross instability could be noted intra-operatively and thus no instrumentation was required.

Histopathology

Histopathologic evaluation (Figure 3) revealed an undifferentiated small round cell sarcoma, consistent with Ewing’s sarcoma involving fibroconnective tissue and local bone. Immunohistochemical studies show that tumor cells are diffusely positive for CD99 and NKX2.2 and negative for CD45, desmin, cytokeratin, synaptophysin and GFAP; consistent with the specified diagnosis.

Figure 3 (A) Low-power (Hematoxylin and Eosin-stained, ×200 magnification) photomicrograph of Ewing’s sarcoma showing a densely cellular tumor composed of uniform small round blue cells arranged in diffuse sheets with interspersed fibrous septation. (B) High-power (Hematoxylin and Eosin-stained, ×400 magnification) photomicrograph highlighting the classic cytologic features of Ewing’s sarcoma: small round cells with scant pale cytoplasm, round hyperchromatic nuclei, and finely dispersed chromatin.

Continued Treatment and Follow-Up

The patient showed improvement of his symptoms immediately post-op, with motor strength recovering fully within a few days and resolution of his paresthesia right after surgery. He was then referred to the oncology team to continue treatment and evaluation.

He was placed on a chemoradiotherapy regimen consisting of 14 cycles of vincristine, doxorubicin and cyclophosphamide; along with etoposide and ifosfamide; in addition to radiotherapy for local control.

At nearly one year of follow-up post-operatively, the patient remains symptom-free, and no neurological deficits have been noted clinically. Follow-up magnetic resonance imaging and positron emission tomography showed no signs of local recurrence or metastasis.

Discussion

Presenting with a nonspecific variety of symptoms mimicking a wide variety of lumbar spine disc diseases ranging from degenerative disease and herniations to infections, primary spinal Ewing’s sarcoma is a relatively rare and aggressive malignant tumor. Symptoms upon presentation include nonspecific lower back pain, weaknesses or paresthesia of the lower extremities and urinary or fecal incontinence as part of cauda equina syndrome.^9,13,14 Misdiagnosis occurs due to overlapping symptoms and nonspecific MRI features and the degree of clinical suspicion for diagnosis is usually low and diagnosis is delayed, causing increased rates of misdiagnosis, mortality and paralysis.⁸ This is a rare, yet documented pitfall. Kaspers et al reported a mean diagnostic delay of 5.8 months in the pediatric and young adult population.¹⁵

Radiologically, magnetic resonance is the gold standard and most sensitive modality of imaging.^9,14,16,17 Magnetic resonance imaging is crucial for identifying the presence of a mass and its characteristics, such as isointensity on T1-weighted images and hyperintensity on T2-weighted images with homogenous enhancement when contrast agents are given. It is particularly vital for distinguishing neoplastic lesions from more common differential diagnoses. On MRI, a herniated disc typically appears as a flat, focal disc protrusion at the intervertebral disc margin with preserved vertebral bodies and minimal to no epidural soft tissue or contrast enhancement.^9,10,18,19 In stark contrast, lumbar Ewing’s sarcoma frequently presents as a well-circumscribed, bulky epidural, paravertebral, or psoas mass with strong, diffuse, or heterogeneous contrast enhancement.^8,10,20,21 Computed tomography can be complimentary revealing bone destruction and periosteal reactions.⁹ Furthermore, while CT highlights bone destruction, MRI can also demonstrate destructive osteolysis or periosteal reactions in Ewing’s sarcoma, rather than the preserved bone seen in simple disc herniations.^9,11,12

Nevertheless, histological assessments remain crucial for confirming the diagnosis and avoiding mismanagement as nonspecific imaging findings may result in misdiagnosis, particularly in nonmetastatic primary cases.²² One case published by Akeda et al reports misdiagnosis of a patient with MRI imaging mimicking a psoas abscess secondary to spinal infection.¹⁹ Kukreja et al reported on a case of a patient presenting with cauda equina syndrome clinically with an initial misdiagnosis of Koch’s extensive tuberculosis as an infectious etiology behind the patient’s symptoms after MRI imaging was done.²³ In 2018, Bang et al also reported a case of an Ewing’s sarcoma masquerading as a benign nerve sheath tumor on MRI imaging evaluation. The group reports that excisional biopsy later on confirmed the diagnosis as Ewing’s sarcoma.²⁴ Histopathological examination, often obtained through a biopsy or tumor excision, confirms the diagnosis by identifying small round blue cells and positive immunohistochemical markers like CD99 and NKX2.2, which has shown a sensitivity of 93% and specificity of 89%.^{13,21,25–27}

Management of Ewing’s sarcomas typically involves a multidisciplinary team approach between spine surgeons, oncologists and radiation oncologists. The standard of treatment involves surgical excision and decompression, especially in the presence of neurological deficits with stabilization of the spine when needed. Neoadjuvant and adjuvant chemo and radiotherapies are also standard for addressing residual diseases and reducing recurrence risks.^14,21,28 In 2018, Zhang et al performed a retrospective analysis of neurological and survival outcomes on patients with Ewing’s sarcoma presenting with symptomatic spinal cord compression.²⁹ They concluded that first-line treatment must be induction chemotherapy regardless of neurological deficits owing to an association with better event-free and overall survival rates as well as higher rates of en-bloc surgical resection with microscopic negative margins. In their study, both patients with symptomatic cord compression who had received initial chemotherapy or primary surgery first had acceptable recovery of neurological deficits. Nevertheless, this might cause delays in treatment and that is of vital importance for patients presenting with neurological deficits. This is particularly important as different studies report high rates of presentation with neurological compromise ranging from 79 to 94% and 100%.^30–32 Thus, the timing of local treatment surgically is of extreme importance and is considered emergent.

Pediatric clinical trial-based treatment protocols exist. Gupta et al compared the clinical outcomes of different therapeutic strategies in pediatric and adult specialty sarcoma centers. They concluded that despite protocols at adult institutions being institution-specific rather than clinical trial-based, reasonable outcomes could be achieved but overall survival remains inferior to pediatric populations.³³ In the presented case, our patient was placed on the typical protocol of two chemotherapy treatment plans as adjuvant therapy, two weeks apart, after positron emission tomography and brain computed tomography scans were done and were negative. The plan consisted of 14 rounds of vincristine, doxorubicin and cyclophosphamide; along with etoposide and ifosfamide. This was complemented with radiotherapy for local control, especially because tumor-free margins are difficult to obtain.³⁴

As previously discussed, early and aggressive treatment is crucial for improving outcomes. Surgical treatment permits quick decompression of any spinal cord compromise and allows pain relief in cases of instability, when addressed appropriately. Additionally, it may be essential to obtain histological samples for assessment in patients that still lack a definitive histological diagnosis, especially when interventional radiological or minimally invasive biopsy samples are lacking as in our presented case. However, when neurological compromise is not present or when histological diagnosis has already been obtained, recent studies have argued in favor of induction chemotherapy before surgery and theorized that it may reduce micrometastases and has shown comparable neurological recovery rates to surgical decompression if neurological deficit is detected.⁷ Similarly, published data on single-institution experiences has shown reduced risks of local recurrence and increased survival rates after initial surgery followed by systemic chemo and radiotherapies.³⁵ In our patient, follow-up magnetic resonance imaging and positron emission tomography showed no signs of local recurrence or metastasis at around one year post-operatively.

Ewing’s sarcoma of the lumbar spine has been reported to have a generally poor prognosis due to its aggressive nature and potential for early metastasis.¹¹ Outcomes for patients with metastatic or relapsed Ewing sarcoma remain poor despite aggressive multimodal therapy, driving increased interest in immunotherapeutic and molecular-targeted strategies.^36,37 Molecular-targeted approaches largely focus on signaling pathways downstream of the EWSR1::FLI1 fusion, including IGF-1R, mTOR, receptor tyrosine kinases, and epigenetic regulators, with early clinical trials demonstrating limited single-agent activity but supporting combination-based strategies.^38–41 Immunotherapy has been hindered by the immunologically “cold” tumor microenvironment of Ewing sarcoma, characterized by low neoantigen burden, reduced HLA class I expression, and suppressive myeloid populations, which likely explains the lack of efficacy observed with immune checkpoint inhibition.^36,42,43 In contrast, adoptive cellular therapies targeting tumor-restricted antigens such as GD2, GPR64, and EphA2, particularly when combined with tumor microenvironment–modulating approaches, have shown strong preclinical efficacy and represent a promising direction for future therapeutic development.^37,44–46

Some studies report common recurrence rates and lower long-term survival with median progression-free survival reported to be about 12 months for intra-dural cases.²⁸ Early diagnosis and multidisciplinary coordinated treatment strategies have shown improvement in survival outcomes. High indices of suspicion and rapid surgical or chemotherapeutic intervention with early histological confirmation of diagnosis are of utter importance.^21,28

Finally, it is important to acknowledge the inherent limitations of this study. As a single retrospective case report, our findings cannot be broadly generalized, nor can they be used to independently establish definitive, standardized treatment protocols for adult lumbar Ewing’s sarcoma. Larger, multi-center prospective studies are ultimately required to better define optimal therapeutic strategies for this rare presentation.

Conclusion

Due to its rarity, standardized treatment protocols for adult lumbar Ewing’s sarcoma remain elusive. This case underscores the necessity of maintaining a high index of suspicion for neoplastic etiologies, rather than defaulting to common diagnoses like disc herniation, when young adults present with progressive or atypical lumbar symptoms. Early identification, prompt surgical decompression, and aggressive multimodal chemoradiotherapy are critical for optimizing survival, especially given the difficulty of achieving negative surgical margins. Ultimately, rapid, coordinated intervention remains essential to improving outcomes.