Bone and soft tissue case 1. Skull base mass.

•Diagnosis: chordoma

•Clinical: most commonly presents as lytic, destructive bone lesion in the axial skeleton: base of the skull, spine, sacrum and coccyx.

•Immunohistochemistry: tumor cells are positive for cytokeratin, EMA, S100, and brachyury

•Dedifferentiated chordoma has high grade sarcoma component and conventional chordoma component

•Poorly diff chordoma is rare with less than 100 cases reported. Please next case for detail.