Methods that require detection of a change in expression of biomarkers (e.g., the changing transcriptome of exosomes or TEP) are more resource-intensive compared to sarcoma-specific assays such as RT-qPCR/dPCR assays for gene fusions; additionally, biomarkers that are present in healthy cells may give false positives (e.g., CD99 surface expression). Here, CD99 is linked to sarcoma.