Bony clival erosion with inta-cranial calcification is seen in -

Chordomas Chordomas are rare, slow growing, locally aggressive neoplasms of bone that arise from embryonic remnants of the notochord. These tumors typically occur in the axial skeleton and are most common in the sphenooccipital region of the skull base and in the sacral regions. In adults, 50 percent of chordomas involve the sacrococcygeal region, 35 percent occur at the base of the skull, and 15 percent are found elsewhere in the vertebral column,  Craniocervical chordomas most often involve the dorsum sella, clivus, and nasopharynx. They are associated with bone erosion. Purely intrasellar chordoma without bony erosions are very' uncommon. Chordoma of the clivus causes erosion of the clivus and extend in the direction of the nasopharynx as well as posteriorly.