CD99 has historically been used as a marker of PNET/Ewing sarcoma, as well as a subset of spindle cell tumors, including synovial sarcoma and solitary fibrous tumor, although there are other more specific markers now available for these latter tumors. Use of CD99 is not recommended; please contact one of our pathologists for alternative markers.
Subcellular Localization: Membranous
CPT Code(s): 88342 or 88341 (reference only; CPTs may vary)
Turnaround Time: Within 1-2 business days of receipt
Schedule: Monday - Friday
• Formalin-fixed, paraffin-embedded (FFPE) tissue block or cell block - OR -
• 1 unstained slide for each test requested plus 3-4 additional unstained slides cut at 4µm