Thoracic epidural Ewing sarcoma mimicking an epidural abscess: A case report.

INTRODUCTION AND IMPORTANCE: Ewing's sarcoma (ES) is a malignant mesenchymal tumor that is categorized as a primitive neuroectodermal tumor (PNET) and is a member of the "small round-cell tumor" family. Spinal extraosseous extradural lesions are highly uncommon in PNETs. There are few clinical studies and information on extra-osseous Ewing tumor outcomes.

CASE PRESENTATION: A 19-year-old woman, with progressive dull aching low back pain of a duration of one month presented. Examination revealed, no knee or ankle reflexes and an MRC power of 0/5 across bilateral ankle and knee joints. The bilateral lower limb's pain, touch, and temperature all received a score of 0/2 on the sensory grading scale. An x-ray revealed radio-opacity at the 9th and 10th thoracic vertebra. The diagnosis of Pott's spine having a likely tubercular abscess was made after an MRI revealed a heterogeneously enhancing collection at T9-T10 communicating with the posterior epidural space. During surgery, an isolated epidural mass with no apparent bony extension was present. The diagnosis was changed to EES based on the results of the histopathology and CD 99 immunohistochemistry tests. Chemotherapy was started. Following up with the patient two months later revealed that her power and sensation in both lower limbs had improved.

CLINICAL DISCUSSION: Usually, children and young adults are affected by Ewing's sarcoma. Due to the rarity of extradural thoracic Ewing sarcoma, its exact prevalence is unknown, Most EES have early distant metastases to the lungs and bones and are rapidly growing. It exhibits the compressive myelopathy symptom. It is challenging to distinguish EES from other spinal tumors and from the TB spine because no specific radiologic patterns for intra-spinal EES and PNETs have been described. Due to its rarity, the spinal epidural treatment protocol is not well established. However, the reported cases show that excision and combined radiotherapy have promising outcome.

CONCLUSION: Epidural Ewing sarcoma should be one of the differentials even in the region with a high prevalence of Potts's spine in young patients presenting with back pain and myelopathy-like symptoms. Ewing sarcoma treatment plans are subject to significant, even month-to-month, changes.