<prompt> Chordoma can occur over all the following sites, except -RibClivusSacrumVertebral body  <response>: Chordoma occurs only in vertebrae and clivus ChordomaChordoma is a rare malignant tumour originating from the remnants of the primitive notochord.As the vertebrae develop, notochord disappears and in adults, the normal remnant of notochord is nucleus pulpous of the intervertebral disc. In chordoma, this embryonic notochordal foci remains inside the vertebral body and forms tumours.It occurs in adult males after 50 years.It commonly occurs in the sacrococcygeal or in the sphere-occipital regions. The sacrum is the most common site: - Sacrum 50 clivus 35, cervical thoraciclumbar 15.Most of them occur in vertebral bodies. 