6P Extraosseous central nervous system Ewing sarcoma: A single-center retrospective case series

Abstract

Background Ewing Sarcoma (ES) tumors are malignant tumors mainly affecting pediatric patients. Extra-osseous primary sites are infrequent, being central nervous system (CNS)-ES extremely rare. Diverse differential histological diagnoses for these “small blue round cell” tumors matched to their rareness make diagnosis an arduous challenge. Methods Our single-center retrospective study included patients with cranial CNS-ES and defining molecular features between 10/2007-11/2023. We analyzed clinical presentation, radiologic and histologic features, and median survival. Results Medical records from twenty-four patients were analyzed. The median age was 22 years (range 2-65); 15 adults (>18). Most patients were male (2:1). Headache was the most frequent symptom (35%), followed by seizures, unilateral numbness/weakness, cerebellar syndrome and visual impairments. Findings in brain Magnetic Resonance Imaging; 11 supratentorial lesions, 7 infratentorial and 6 showed diffuse meningeal infiltration. Histopathology showed in most cases conventional diffuse pattern with small round blue cells (n=12). Confirmatory (11;22) translocation was achieved in all cases: 22 confirmed by Protein-Chain-Reaction analysis and 2 by Fluorescence in situ hybridization for EWSR1 gene rearrangement. One case was confirmed by deoxyribonucleic acid (DNA) methylation profiling. Median overall survival (OS) was 78 months (0-140). 21 patients had an OS exceeding 12 months, while 3 patients suffered rapid progression and died within the year of diagnosis. No significant relations were found between treatment and survival. Conclusions Primary CNS-ES is an orphan pathology and its clinical course and treatment options are barely known. In our experience, it is a heterogeneous group in clinical onset, imaging and histopatological findings, treatment response and outcome. Advances in diagnosis technologies such as DNA methylation profiling with subtypes clustering will probably favour further understanding and guide treatment tayloring.