PTPRC and neoplasm: Immunohistochemical staining (IHC) was performed to determine lineage, however, tumor cells were negative for pan-keratin (Figure 1d), p40, CDX2, HER2, S100, CD45, SOX10, CD34, synaptophysin, chromogranin A, myogenin, DOG1, KIT (CD117), CD30, and ALK.