Chordoma of the petrous bone

We have presented two cases of chordoma arising from an unusual location within the skull. Chordomas in the skull usually arise from within the body of the clivus, reputedly from notochordal remnants. The first case, which was diagnosed both with CT and MRI, had its origin from the petrous bone, with extension into the left cerebellopontine angle. Chordoma was not considered high on the list of differential diagnoses. A right pontine hemorrhage, which was evacuated surgically, was diagnosed in the second case both from its clinical appearance and from that on CT scan. Only when bone windowing technique was used with CT was a lytic lesion of the right petrous bone evident. Chordoma was only diagnosed on autopsy. In reviewing these two cases and the literature, it is evident that chordoma must be considered in the differential diagnosis of erosive lesions of the petrous bone.