Notochordal tumors (chordoma). Differential diagnosis. Immunohistochemical markers

Chordomas, low-grade chondrosarcomas, metastatic carcinomas share many histological features, generating at times, considerable diagnostic difficulty and, not infrequently, requiring immunohistochemical analysis for appropriate classification. In an effort to clarify the diagnosis and differentiation with other cartilaginous tumors, samples from 58 patients with sacrum chordoma were examined by immunohistochemistry with a panel of antibodies. The panel included antibodies to cytokeratin (CK), epithelial membrane antigen (EMA), D2-40, GFAP (glial fibrillary acidic protein), NSE (neuron-specific enolase), chromogranin, TTF-1 (thyroid transcription factor), PSA, CDX-2, mammaglobin. The conventional chordoma stained for CK (16/16) EMA (13/16), NSE (12/16) and was negative for chromogranin, GFAP. Specific markers were helpful in differential with metastatic carcinomas. Chordomas are difficult to excise because of their location and intimate relation to critical structures. Two cases of dedifferentiated chordoma were described.