Primary Extraosseous Spinal Ewing's Sarcomas (PESES): Should we be more aware about Diagnosis?

STUDY DESIGN Single-center retrospective study OBJECTIVE.: We discuss the widespread misdiagnosis of primary extraosseous spinal Ewing's Sarcomas (PESES) to begnin tumors leading to poor treatment SUMMARY OF BACKGROUND DATA.: Primary extraosseous spinal Ewing's Sarcomas (PESES) is a particular entity of Spinal Ewing's sarcoma (SES) appearing in a similar shape and features to benign tumors such as schwannomas. This imaging mimicry and subsequent possible misdiagnosis lead to primary surgery, without neoadjuvant chemotherapy, which remain deleterious for survival and progression. METHODS We identified a total of 13 patients: 7 women (53.8%) and 6 men operated between 2001-2018 for PESES and initially misdiagnosed as schwannomas or ependymomas RESULTS.: The mean age of our series was 35.8 years (range, 18.1-47.2y). The first clinical symptom was neuralgia (61.5%) followed or associated with nerves deficits (38.5%). Median progression free survival (PFS) was 31.7 months (SD 5.8). Tumor recurrence rates at 1 and 3 years were respectively 21.2% (SD 3.1) and 60.1% (SD 15.8). Median overall survival (OS) was 61.5 months (SD 16.27). The 1-year, 2-year, and 5-year survival estimates were 100.0%, 88.9% (SD 10.5), and 44.4% (SD 16.6). 6 patients (46.13%) died following their SES. In univariate analyses, patients with metastastic PESES had a significantly lower OS than others (41.2 months, p = 0.03). CONCLUSION PESES must be ruled out at diagnosis of a spinal tumor when facing a fast-growing lesion with neurological deficits in a young adult. Thoraco-abdomino-pelvic extension should be carried out. Pre-surgical biopsy must be performed. In case of PESES, neoadjuvant chemotherapy must be established before considering surgical intervention. LEVEL OF EVIDENCE 4.