Demonstration of cytokeratins and an epithelial membrane antigen in chordomas and human fetal notochord.

The application of immunohistochemical staining with anti-epithelial monoclonal antibodies to the differential diagnosis of chordomas is described. Cytokeratins and an epithelial membrane-specific oligosaccharide sequence are found in chordomas but not in chondrosarcomas or normal cartilage. The same cytokeratins and oligosaccharide sequence are demonstrated in human fetal notochord. Immunohistochemical staining with antiepithelial antibodies is therefore of value in distinguishing chordomas from cartilaginous tumours. The staining of notochord with the same monoclonal antibodies adds weight to the proposition that chordomas arise from embryonic rests of notochordal cells.