Mesenchymal chondrosarcoma: A clinicopathologic and flow cytometric study of 13 cases presenting in the central nervous system

BACKGROUND. Mesenchymal chondrosarcomas arising in the central nervous system are extremely rare. Morphologic features have not been found to correlate reliably with prognosis. METHODS. Eight intracranial and five intraspinal mesenchymal chondrosarcomas were reviewed with regard to location, treatment, and long term follow-up data. The histopathologic and immunohistochemical results, including Ki-67 nuclear staining frequency, were critically reviewed, and deoxyribonucleic acid content was analyzed by flow cytometry. RESULTS. Microscopically, all 13 cases were remarkably similar. Immunoreactivity in the small cell component included vimentin in 100%, and cytokeratin and glial fibrillary acidic protein in 25% of cases, S-100 immunoreactivity was noted in the cartilaginous component of 100% of cases, and in rare cells in the small cell component along the interface. Flow cytometry of the eight tumors studied revealed a diploid pattern in six, aneuploidy in two, and a wide range of S-phase fractions (0-36.5%). CONCLUSIONS. Review of the literature and the findings of the current series indicates that mesenchymal chondrosarcomas presenting in the brain and spinal cord pursue a progressive course that correlates most reliably with extent of surgical resection. This limited retrospective study also suggests that survival may be shorter for those patients with a high S-phase fraction and a high Ki-67 staining frequency.