Pathology of chordoma and chondrosarcoma of the axial skeleton

The skull is an uncommon location for primary bone tumors. Those that arise in this location are often malignant, and the most common are chordoma and chondrosarcoma. These tumors have some overlapping clinicopathological features but can be distinguished by their morphology and immunohistochemical profile. Histologically chordoma demonstrates lobules of cohesive polyhedral cells with vacuolated cytoplasm in a mucinous or myxoid matrix; immunohistochemistry for brachyury is positive. Chondrosarcoma shows chondrocytes with increased cellularity and atypia in a hyaline or myxoid cartilaginous matrix; immunohistochemistry for brachyury is negative. Chordoma is the most common primary sarcoma of the axial skeleton and arises with approximately equal frequently in the skull base, mobile spine, and sacrococcygeal region. The spine is a more common site than the skull base for chondrosarcoma. Chordoma and chondrosarcoma are usually treated by a combining surgical resection and radiation therapy. Overall, chondrosarcoma has a better prognosis than chordoma.