Expression of E-cadherin in chordomas: diagnostic marker and possible role of tumor cell affinity

Chordoma is a relatively rare malignant bone tumor thought to arise from the remnants of the fetal notochord. Chordomas express epithelial cell markers such as cytokeratin and epithelial membrane antigen (EMA), which strongly suggests that the tumor cells grow via the mechanism of epithelial characterized cell-cell interactions. However, there are no known reports that have studied epithelial characterized cell-adhesion molecules such as E-cadherin or epithelial cell adhesion molecule (Ep-CAM) in chordomas. An immunohistochemical investigation was performed in seven cases of chordoma to determine the expression of pan-cytokeratin, Ep-CAM, and E-cadherin. Histological specimens showed the typical appearance of conventional chordoma but for two cases of chondroid chordoma. Cytokeratin was constantly expressed in conventional chordomas, but it was detected among a few cells with physaliphorous appearance in chondroid chordoma cases. Although no Ep-CAM expression was noted, E-cadherin was detected in most chordoma cells irrespective of histological subtypes. The expression of E-cadherin was negative among chondrosarcoma cells in this study as previously reported, and thus constant E-cadherin expression of chordoma cells suggests a role as a useful diagnostic marker to distinguish chondroid chordoma from chondrosarcoma. Furthermore, we speculate that E-cadherin may play a role in tumor cell adhesion and is also involved with histological and clinical features in chordomas.