These studies have been hampered by relatively poor sensitivity, and the use of putatively histology-specific markers (such as CD99 for Ewing sarcoma) not only may not increase specificity (since B lineage cells also express CD99) but limits general applicability of the technique, since many sarcoma histologies lack a specific cell surface marker (for example, osteosarcoma). This evidence concerns the gene CD99 and Ewing sarcoma.