Chordoma is a malignant bone tumour of notochord origin. It accounts for approximately 5% of primary malignant bone tumours and is usually diagnosed during the 4th to 8th decades of life. It is primarily found in the axial skeleton. The most common site of involvement is the sacrum, followed by the base of the skull and mobile spine.

Clinical features depend on the primary site of origin. In the sacrum, one may present with pain, constipation, incontinence, bladder dysfunction or erectile dysfunction. In the mobile spine, pain is the most common complaint. In the base of skull, cranial nerve palsies are the most common presentation.

Macroscopically, the tumour appears soft, gelatinous and lobulated. Tumours in the skull base commonly measure 2-5 cm in greatest dimension. In the sacrum, tumours commonly measure greater than 10cm. Microscopically, conventional chordoma has a lobular growth pattern and is composed of large epithelioid cells arranged in cohesive nests and cords. Intracytoplasmic vacuoles are present. Mitotic activity is usually low.

Immunohistochemical staining is positive for cytokeratin 8 and 19, and epithelial membrane antigen. This is helpful in distinguishing chordoma from chondrosarcoma, which is negative for cytokeratin markers. As well, chordoma is positive for S100 staining.