ABSTRACT
Some non-neoplastic lesions are included here because of their similarity to true bone tumours, though they are usually omitted from pathological classifications. Table 9.1 shows one such listing, based on the Revised World Healthy Organization (WHO) Classification of bone tumours. A few caveats are worth mentioning:
The most pervasive tissue is not necessarily the tissue of origin.
There is not necessarily any connection between conditions in the ‘benign’ category and the corresponding ‘malignant’ category.
There is often no relationship between benign and malignant lesions with similar tissue elements (e.g. osteoma and osteosarcoma).
By far the commonest malignant lesions in bone are metastatic tumours, which are not, strictly speaking, ‘bone’ tumours, i.e. not of mesenchymal origin.
