Cytogenetic investigation of chordomas of the skull.

We report the first cytogenetic investigation of cranial chordoma. Three cranial chordomas were examined, two of which could be further histopathologically classified as chondroid chordomas. In addition, we have included a case of chordoma of a cervical vertebra to compare the cytogenetic abnormalities. Diagnosis was made at histological and immunohistochemical levels. The three cases of cranial chordoma showed a normal karyotype, while one vertebra showed 46,XY,t(6;11)(q12;q23). Chordomas, particularly those containing cartilage, have to be distinguished from chondrosarcomas of the skull base. Such a distinction is normally based on expression of epithelial markers which usually are lacking in chondrosarcoma. Cytogenetic investigation may eventually prove to be useful in the distinction of the two lesions, if chromosome anomalies are consistently absent in chordoma, although some chondrosarcomas may also present a normal karyotype. Such a distinction has clinical implications because chondroid chordomas show better survival, whereas chondrosarcomas show a propensity to infiltrate the surrounding tissues.