Chondrosarcoma
Definition and Presentation
A rare cartilage forming tumour of the skeleton. When arising in
the skull its usual location is the skull base. These tumours grow
slowly and usually present by their mechanical effect on
neighbouring normal structures. Thus headache and double vision are
common. Hearing loss, swallowing difficulties, facial numbness and
other symptoms can also occur.
Diagnosis
The diagnosis can be made on CT and MRI. The differentiation
from chordoma (see below) is however difficult or impossible and
rests on microscopic examination of the tumour specimen
(biopsy).
Treatment
Chondrosarcomas grow locally and slowly. By the time the patient
experiences symptoms they are usually large. Surgical removal is
then the treatment of choice. Advanced skull base surgical
techniques are required, but often residual tumour must be left to
reduce major complications. It has been shown that post-operative
conventional radiotherapy prolongs recurrence free survival in
these patients but large doses of radiation are required. In
selected cases Gamma Knife surgery may be the most efficient and
safe way to deliver a radiation dose which is lethal to the
tumour.