Classification of bone tumours.

Primary tumours of bone can be classified conveniently into distinct groups based on the appearance of the tumour cell, or its product, or both. Almost all the groups have benign and malignant counterparts. However, malignant bone tumours usually do not arise from benign tumours. Although the cell of origin in many tumours is unknown, the classification described in this paper refers to well-defined clinicopathologic entities, so that the behaviour of a given tumour can be anticipated. This classification is accepted the world over and provides a "common language" for those who treat patients with bone tumours.