(i) The epidemiology of primary skeletal malignancy

Primary skeletal malignancy is rare although in adulthood myeloma is not uncommon, with an estimated incidence of nine per million persons per year. It should not be confused with metastatic disease. The most common type of primary bony malignancy is plasmacytoma, after that chondrosarcoma, osteosarcoma and Ewing’s sarcoma. The a priori chance of a patient to have a certain type of tumour depends on the patient’s age. The most frequently seen under the age of 20 are osteosarcomas and Ewing’s sarcomas. In adults, especially those over 40 years old, myeloma is the most common one, followed by chondrosarcomas and fibrous tumours. It is important for all treating patients with complaints of the musculoskeletal system to be aware of the possibility of primary bone cancer in order to prevent unnecessary delay and incorrect treatment.