Immunohistochemical comparison of chordoma with chondrosarcoma, myxopapillary ependymoma, and chordoid meningioma.

Chordoma originates from embryonic notochordal remnants in the midline along the spinal axis and is characterized by cords and lobules of neoplastic cells arranged within myxoid matrix. Because of histologic similarities with myxoid matrix and overlapping immunohistochemical profile, chondrosarcoma, myxopapillary ependymoma, and chordoid meningioma enter in the histologic differential diagnosis at this site. Therefore, the judicious use of a panel of selected immunostains is unquestionably helpful in diagnostically challenging cases. To find useful immunohistochemical markers for assisting in differential diagnosis between chordoma and other tumors with chordoid morphology, an immunohistochemical study using D2-40, epithelial membrane antigen (EMA), pan-cytokeratin (panCK), glial fibrillary acidic protein (GFAP), S-100 protein, galectin-3, neural cell adhesion molecule (NCAM), beta-catenin, E-cadherin, and carcinoembryonic antigen was performed on 14 chordomas, 7 chondrosarcomas, 9 myxopapillary ependymomas, and 4 chordoid meningiomas. Chordoma typically showed positive for EMA and panCK and negative for D2-40 and GFAP; whereas chondrosarcoma revealed positive for D2-40, and negative for EMA, panCK, and GFAP; myxopapillary ependymoma positive for GFAP and negative for EMA; and chordoid meningioma positive for EMA, and negative for panCK and GFAP. On the basis of our immunohistochemical study, a panel of D2-40, EMA, panCK, and GFAP allowed the correct recognition of all tumors examined. Other immunohistochemical markers including S-100 protein, galectin-3, NCAM, beta-catenin, E-cadherin, and carcinoembryonic antigen were of little value in differential diagnosis. In summary, the best immunohistochemical markers useful for the evaluation of tumors with chordoid morphology were D2-40, EMA, cytokeratin, and GFAP. D2-40 was a true chondroid marker to be useful for the differential diagnosis with chordoma.