The most common sites of chondrosarcoma origin are the petroclival, petro-occipital, spheno-occipital
, and sphenopetrosal synchondroses.
1,2) They usually originate from the bones of the skull base, at the sphenoethmoidal and spheno-occipital
regions, but very rarely can also arise from other intracranial, extraosseous sites like the dura mater, the brain parenchyma or from within the ventricles.
3,5] They originate from the sacrococcygeal region, the spheno-occipital
region or the vertebrae, with 35%-40% located intracranially.
The lesion extended distally to the spheno-occipital
synchondrosis, anteriorly into the nasopharynx, and superiorly into the suprasellar cistern.
They are divided into three broad categories: sacrococcygeal (60% of cases), spheno-occipital
(25%), and vertebral (15%).
An estimated 50% of chordomas are sacrococcygeal, and 35% are spheno-occipital.
3) Virchow believed that they originated from the spheno-occipital synchondrosis.
Approximately what percentage of chordomas are classified as spheno-occipital
, according to a source cited by Lynn-Macrae et al?