Causes / typical injury mechanism: Classical chordoma is a rare, slow-growing, low-to-intermediate grade primary malignant tumor of bone that is believed to be derived from remnants of notochord. 

Classic history and presentation: The most common primary sites are within the axial skeleton: the sacrum / coccyx, skull base / clivus, and mobile spine.

Prevalence: Incidence of chordomas is about 1 per 1 million, and these tumors comprise 1%-4% of all primary malignant bone tumors.

• Age – Chordomas usually occur in patients older than 40 years (peak incidence at age 50-60 years) and rarely occur in the pediatric population.
• Sex / gender – Chordomas are more common in men.

Pathophysiology: Pathophysiology is believed to be malignant degeneration of notochordal rests. Chordoma metastasizes mostly to the lungs and rarely to other bones.

Grade / classification system: Chordoma typically behaves in a low-to-intermediate grade manner with local recurrences being problematic after surgically treated disease.

There are several chordoma histologic variants –

• Classical chordoma: 97% of all chordoma cases
• Chondroid chordoma: best prognosis
• Dedifferentiated chordoma: worst prognosis
• Poorly differentiated chordoma: defined only recently