This is a chordoma arising in the region of the clivus. Chordomas are derived from notochord and comprise about 4% of primary malignant bone tumors. The peak incidence is in the 6th decade. Half are located in the sacrococcygeal region and a third, as in this case, arise in the spheno-occipital region and can produce symptoms related to increased intracranial pressure or to cranial nerve compression. Their location makes wide excision and complete resection difficult, so recurrences are common. Grossly, chordomas are usually ill-defined gray-white masses with a slimy cut surface. Microscopically, the cells have abundant vacuolated cytoplasm. Large cells with multiple vacuoles are called 'physaliferous cells' because of a resemblance to jellyfish. Immunoperoxidase staining can reveal positivity for cytokeratin, S-100, vimentin, and epithelial membrane antigen.