WHO Classification of Tumours

The WHO classification of tumours includes a range of common and essential pathology that present as swellings or space-occupying lesions in the oral and maxillofacial regions. The terms neoplasia and tumour are sometimes used interchangeably and can cause some confusion to learners, particularly in their undergraduate degrees, and this is clarified in the chapter. The pathogenesis of the oral and maxillofacial tumours included in the WHO classification of Head and Neck Tumours includes various processes, mainly reactive inflammatory, neoplastic, developmental, immune-mediated, and those with unknown aetiology but known pathogenesis such as metabolic or hormonal. The bulk of the tumours are either reactive inflammatory or neoplastic. Although the pathological basis of these tumours is described in more detail in other chapters as highlighted in the text, an overview of key tumours is presented in this chapter, putting them in the context of their pathogenesis within the WHO classification.