Skull base

Question 1

Skull base DDx (2)

Answer 1

Chordoma,
Chondrosarcoma

Question 2

Chordoma (4)

Answer 2

Locally agressive tumour originating from the notochord (midline structure relating to spinal development).
Therefore all chordomas are midline, either Clivus, vertebral bodies (especially C2) or sacrum.
Always T2 bright

Question 3

Chrodosarcoma (4)

Answer 3

Main differential of chordoma in the clivus.
Nearly always lateral to the midline.
Also T2 bright, with “arcs and rings” matric on chondrosarcoma.
Needs CT to describe that