Chordomas are uncommon malignant tumours that account for 1% of intracranial tumours and 4% of all primary bone tumours.
They originate from embryonic remnants of the primitive notochord (earliest fetal axial skeleton, extending from the Rathke’s pouch to the coccyx). Since chordomas arise in bone, they are usually extradural and result in local bone destruction. They are locally aggressive, but uncommonly metastasise.
Chordomas are found along the axial skeleton and a relatively evenly distributed among three locations: sacrococcygeal, spheno-occipital and vertebral body.
The clival region accounts for 30-35% 2-3 of cases. Typically the mass projects in the midline posteriorly indenting the pons. This characteristic appearance has been termed the ‘thumb sign’. In contrast to sacrococcygeal tumours, there is currently no recognised gender difference.
– Measurements: 18×24”/46x61cm