"They are thought to arise from embryonal crest cells (remember that the base of the skull forms via endochondral ossification). Chondrosarcoma is composed of a cartilaginous matrix with chondrocytes inside the lacunae. Direct bone formation by tumoural cells is usually not seen6. Tumoural chondrocytes arranged in a diffuse or lobular pattern, depending on grade:"
"Chondrosarcomas of the base of the skull follow the same general imaging characteristics of chondrosarcomas elsewhere – see generic chondrosarcoma article. Importantly CT and MRI are complementary, the former exquisitely delineating the relationship to the skull base and showing calcification within the mass, whereas the latter giving important information on signal intensity and relationship to neural structures."
"T1: low signal"
"T2: high signal"
"SWI/GRE: calcifications show low signal"