[Intraosseous sarcoma with osteoid production and evidence of an EWSR1::SSX1 gene fusion].

Abstract

The WHO Classification of Bone and Soft Tissue Tumors comprises more than 170 defined tumor entities. Moreover, an increasing number of very rare mesenchymal neoplasms with distinct molecular alterations are being described. In the present case of an intraosseous tumor in a 34-year-old woman, RNA-based targeted panel sequencing identified an EWSR1::SSX1 fusion. Following interdisciplinary discussion, this led to the working diagnosis of synovial sarcoma and influenced treatment planning. This case highlights the diagnostic value of molecular sequencing in diagnostically challenging sarcomas.