A Spinal Cord Sarcoma With EWSR1::WT1 Fusion Exhibited Ewing Sarcoma-Like Pattern Rather Than Desmoplastic Small Round Cell Tumor.

We received a case of a 22 years old female, with a spinal cord sarcoma. The tumor exhibited a morphology similar to that of a small blue round cell tumor, lack of desmoplastic stroma. Immunohistochemical analysis demonstrated diffusely membranal expression of CD99 and cytoplasmic expression of Desmin, but was negative of NKX2.2. Fluorescence in situ hybridization indicated the EWSR1 gene rearrangement. Next generation sequencing (NGS) identified a gene fusion of EWSR1(E9)::WT1(E8). The fusion gene was confirmed by RNA NGS as well. There was a challenge on diagnosis whether should it be diagnosed as Ewing sarcoma-like tumor or DSRCT. Conclusion: The EWSR1::WT1 fusion tumor has a wide spectrum of diseases. The morphology may be associate with specific gene breakage site, or/and tissue specificity. Final diagnosis should be rendered based on comprehensive correlation of clinical presentation, morphology, immunophenotype, and molecular finding.