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 Table of Contents  
CASE REPORTS
Year : 2021  |  Volume : 4  |  Issue : 2  |  Page : 240-242

An atypical presentation of metastatic Ewing sarcoma to the spine


1 MOH Holdings Pte Ltd, 1 Maritime Square, Singapore
2 Department of Pathology, National Neuroscience Institute, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore, Singapore
3 Division of Spine Surgery, Department of Orthopaedic Surgery, National Neuroscience Institute, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore, Singapore
4 Department of Neurosurgery, National Neuroscience Institute, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore, Singapore

Date of Submission03-Jan-2021
Date of Decision12-May-2021
Date of Acceptance17-May-2021
Date of Web Publication16-Jul-2021

Correspondence Address:
Wei Jie Tan
MOH Holdings Pte Ltd, 1 Maritime Square.
Singapore
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ISJ.ISJ_2_21

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  Abstract 

Ewing sarcoma (ES) is a rare malignancy of the young, primarily arising from the bones. Uncommonly, it can arise extraskeletally and, among the rarest cases, from the spinal extradural tissues. The patient is a previously well 26-year-old male who presented with radicular low back pain. Magnetic resonance imaging revealed an L5-S1 spinal canal mass with possible metastases to the vertebral and pelvic bones. The initial diagnosis was challenging, with differentials of an intradural tumor, infection, solid organ tumor metastasis, and lymphoma. The patient subsequently underwent decompression and debulking of his spinal tumor, which was found to be extradural. Histological and pathological studies supported the diagnosis of metastatic ES. This case report highlights an atypical presentation of ES. Although exceedingly rare, young patients can still present with metastatic spinal disease. Clinicians should always consider more sinister diagnoses and investigate further, especially if red flag symptoms are present.

Keywords: Cauda equina syndrome, epidural neoplasms, Ewing sarcoma, spine


How to cite this article:
Tan WJ, Lee HY, Yap WM, Nolan CP, Oh JY. An atypical presentation of metastatic Ewing sarcoma to the spine. Indian Spine J 2021;4:240-2

How to cite this URL:
Tan WJ, Lee HY, Yap WM, Nolan CP, Oh JY. An atypical presentation of metastatic Ewing sarcoma to the spine. Indian Spine J [serial online] 2021 [cited 2021 Dec 4];4:240-2. Available from: https://www.isjonline.com/text.asp?2021/4/2/240/321562




  Introduction Top


Ewing sarcoma (ES) is a rare malignancy primarily arising from the bones, although extraskeletal Ewing sarcomas (EES) do occur. Patients usually present with local pain, swelling, and compressive symptoms from the tumor.[1],[2] ES has a reported incidence of 2.9 cases per 1,000,000 population while EES affecting the spine is more rare. A meta-analysis in 2012 had found only 106 such cases reported in the literature, of which 38% of the cases had distant metastasis.[2],[3] We present a rare case of a 26-year-old adult male who presented with subacute cauda equina syndrome. The initial diagnosis was challenging with differentials of an infection, solid organ metastasis, or even an intradural tumor. He was eventually diagnosed with metastatic ES causing cauda equina compression to the L5-S1 spine.


  Case Report Top


A previously healthy 26-year-old Asian construction worker presented with an insidious onset of low back pain for one month. It was associated with left L5-S1 radiculopathy, with radiating pain and paresthesia down his left posterior thigh, extending to his lateral calf and sole. In addition, he complained of poor urinary flow which started 2 weeks prior to admission. There was no preceding trauma or constitutional symptoms of weight loss, fever, or night sweats.

On examination, the patient had full power in all myotomes of his lower limbs and reduced sensation over his left L5 and S1 dermatomes based on the American Spinal Injury Association (ASIA) Impairment Scale.[4] Bilateral knee and ankle reflexes were normal. His anal tone was intact but he had reduced sensation over his left perianal region. Lasegue’s sign was positive on the left at an angle of 50°. A bladder scan showed a post-void volume of 200 mL. His initial laboratory investigations were unremarkable. Full blood count and renal panel values were within normal ranges, C-reactive protein was 11, and erythrocyte sedimentation rate was 12. Radiographs of his lumbar spine were normal.

The clinical impression at that point in time was a prolapsed intervertebral disc causing subacute cauda equina syndrome. Instead, a contrasted magnetic resonance imaging (MRI) of his lumbar spine revealed a 3.5 cm central canal mass opposite L5-S1, impinging the bilateral S1 descending nerve roots and the rest of the sacral nerve roots [Figure 1]A and B]. Several other rim-enhancing osseous lesions were also seen in the sacral ala, S2, and left iliac bone [[Figure 1]C.
Figure 1: (A) Sagittal T2-W MRI: 3.5 cm long central canal mass opposite L5-S1 (B) Axial T2-W MRI of the lesion at the S1 level. (C) Axial T1-W with contrast MRI showing multiple rim enhancing osseous lesions of the pelvis

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The diagnosis at this point in time was challenging. We entertained the possibility of a metastatic tumor initially, but thought that this was less likely given his young age and a normal CT scan ruling out any solid organ tumors. Thus, other differentials including an intradural tumor and an infective process were considered based on the MRI findings. The possibility of lymphoma was also entertained; however, this was also less likely as the patient did not report any B-symptoms. A screen of tumor markers AFP, CEA, PSA, and CA 19-9 was normal. Subsequent MRI scans of his whole spine and pelvis revealed further sites of likely metastasis in his T2 and T9 vertebral bodies, sacrum, bilateral acetabulum, and iliac bones. Focal aggressive marrow changes were noted in these areas, with raised STIR signal and heterogenous enhancement. MRI of his brain was normal.

In view of symptoms suggestive of subacute cauda equina syndrome, surgery was arranged. The patient underwent successful L5-S1 laminectomy and debulking of his spinal tumor on day 5 of admission. Intra-operatively, the tumor was found to be extradural, contrary to what was previously thought. No obvious tumor invasion into the thecal sac was noted, and the tumor was debulked until the thecal sac was free and mobile bilaterally, with preservation of nerve roots.

Histological samples taken intra-operatively showed fibroadipose tissue with an extensively necrotic tumor. Focally, where the tumor was better preserved, small round cells with high nuclear cytoplasmic ratios and rounded nuclei containing finely granular chromatin and small nucleoli were seen [Figure 2]A and B. The tumor cells showed strong membranous staining for CD99, characteristic of ES [Figure 2]C. Fluorescence in situ hybridization (FISH) showed an EWSR1 gene rearrangement, consistent with ES.
Figure 2: (A and B) Microscopic images of the tumor showing round cells with high nuclear cytoplasmic ratios. The nuclei of the tumor cells show finely granular chromatin and small nucleoli (H&E ×400, H&E ×600). (C) Immunohistochemistry for CD99 showing strong membranous staining in the tumor cells (CD99 ×400)

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The patient recovered well post-operatively with immediate improvement of his radicular and urinary symptoms. He was discharged on post-operative day 5 and referred to an oncologist for subsequent treatment.


  Discussion Top


Our case is unique as a diagnostic dilemma in an atypical presentation of ES. What was initially thought to be a case of prolapsed intervertebral disc was later thought to possibly be an intradural tumor, infection, or metastatic disease after MRI imaging. Metastatic disease was later excluded after CT imaging did not reveal any solid organ tumors. The patient’s young age made malignancy less likely, although lymphoma was still being considered. Eventually, the diagnosis was confirmed by histological studies taken intra-operatively which revealed the rare diagnosis of a masquerading ES.

Although ES predominantly arises from both long and flat bones, primary EES also occurs, accounting for about 30% of the total cases.[1] Primary intraspinal EES/peripheral primitive neuroectodermal tumors (pPNET) such as the case reported herein are even rarer. A 2012 meta-analysis by Saeedinia et al.[5] had found a total of 106 reported cases in the literature. Distant metastasis occurred in 38% of these cases, mainly to the lungs, bone, brain, and other parts of the spine. Common symptoms on presentation included local and radicular pain, muscle weakness, and sphincter dysfunction. The mean duration of symptoms before diagnosis was 4.5 months.

Importantly, back pain is a common presenting symptom which could often be initially misdiagnosed and attributed to a benign musculoskeletal cause, especially in younger patients. The patient reported herein was initially diagnosed with a prolapsed intervertebral disc but was later discovered to have a rare epidural malignancy. In addition, constitutional symptoms of weight loss, fever, or fatigue have been reported in only 20% of the EES, reducing the number of red flag symptoms that could alert a clinician to a more sinister diagnosis.[6]

Conclusion

In conclusion, it is pertinent to exclude rarer and more sinister causes of low back pain in the young with more detailed imaging, especially if the symptoms are persistent, worsening, have an insidious onset, or accompanied with symptoms of cord compression.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Jiang S, Wang G, Chen J, Dong Y. Comparison of clinical features and outcomes in patients with extraskeletal vs skeletal E sarcoma: An SEER database analysis of 3,178 cases. Cancer Manag Res 2018;10:6227-36.  Back to cited text no. 1
    
2.
Maheshwari AV, Cheng EY. Ewing sarcoma family of tumors. J Am Acad Orthop Surg 2010;18:94-107.  Back to cited text no. 2
    
3.
Esiashvili N, Goodman M, Marcus RB Jr. Changes in incidence and survival of Ewing sarcoma patients over the past 3 decades: Surveillance epidemiology and end results data. J Pediatr Hematol Oncol 2008;30:425-30.  Back to cited text no. 3
    
4.
Roberts TT, Leonard GR, Cepela DJ. Classifications in brief: American Spinal Injury Association (ASIA) impairment scale. Clin Orthop Relat Res 2017;475:1499-504.  Back to cited text no. 4
    
5.
Saeedinia S, Nouri M, Alimohammadi M, Moradi H, Amirjamshidi A. Primary spinal extradural Ewing’s sarcoma (primitive neuroectodermal tumor): Report of a case and meta-analysis of the reported cases in the literature. Surg Neurol Int 2012;3:55.  Back to cited text no. 5
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6.
Rud NP, Reiman HM, Pritchard DJ, Frassica FJ, Smithson WA. Extraosseous Ewing’s sarcoma. A study of 42 cases. Cancer 1989;64:1548-53.  Back to cited text no. 6
    


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