Chordoma is a tumour of the remnants of the notochord. It is very rare.
Epidemiology
Chordomas are uncommon tumours, making up about 2% of primary bone tumours. They are more common in men and most commonly develop in the 50s.
Site
Chordomas typically arise in the sacrum (60%), clivus (25%), cervical spine (10%) or thoracolumbar spine (5%).
Aetiology and Pathogenesis
The cause is unknown.
Natural History
The tumour is slow growing and symptoms are often present for some time prior to diagnosis. Symptoms relate to the site; sacral tumours present with pain and sacral neuropathy; clival tumours with headache and cranial neuropathies (usually ocular), and spine tumours with pain and neuropathy.
Imaging
The imaging findings are of a destructive, lobuated mass that replaces the bone and invades adjacent tissue. Metastases are rare.
Tumour Features
Macroscopically, chordoma is a grey to light blue, glistening, lobulated tumour. Haemorrhage is frequently seen but necrosis is not.
Microscopically, the tumour is lobulated. The lobules are separated by fibrous bands of tissue. The cells are vacuolated and fairly uniform in appearance; mitoses are rare; the background is myxoid. The cells can be arranged in sheets, cords or singly.
Immunohistochemistry is positive for S100, AE1/3, other cytokeratins, and epithelial membrane antigen.
