In Collaboration with Pathologists in 7 Countries

This is a histological classification of tumours and tumour-like lesions of the exocrine pancreas which also includes those tu- mours showing a mixture of exocrine and endocrine elements. The classification is based principally on standard microscopic observations, but whenever indicated it incorporates diagnosti- cally valuable immunohistological findings. In addition, the most important immunohistological findings which are helpful in cat- egorizing pancreatic tumours are summarised in Table 1. The major guideline of this classification scheme is the group- ing of the pancreatic exocrine tumours according to their biologi- cal behaviour. Thus, the neoplasms are broadly divided into benign (adenoma) and malignant tumours (carcinoma). How- ever, in recent years we have learned that this division is not a sharp but rather a gradual transition. We therefore added a third group which we call "tumours of uncertain malignant potential" representing a borderline category analogous to that recognized for some ovarian tumours. This group includes mucinous cystic tumour, intraductal papillary-mucinous tumour and solid- pseudopapillary tumour. These neoplasms are defined by the grade of dysplasia and/or potential to become malignant. Mucinous cystic tumours of uncertain malignant potential, for instance, exhibit moderate epithelial dysplasia, but do not show severe dysplasia/carcinoma in situ changes, nor carcinomatous invasion of the cyst wall or the adjacent pancreatic tissue. Solid- pseudopapillary tumour has a benign looking histological ap- pearance, but metastases may occur. Biologically, all these neoplasms are primarily slow-growing lesions and have an excel- lent prognosis when adequately treated by complete resection.

"The WHO Classification of Tumours of the Digestive System presented in this book reflects the views of a Working Group that convened for an Editorial and Consensus Conference at the International Agency for Research on Cancer (IARC), Lyon, December 10-12, 2009"--P. [5].

This book includes more clinical aspects and concentrates on cancer and precancer of the oral mucosa rather than attempting to cover all benign and malignant tumours of the oral and oropharyngeal tissue. One main emphasis is the significance of the clinical features of the various lesions discussed. Attention is also drawn to those conditions particular to the oral mucosa that may give rise to appearances which are important in differential diagnoses but can be misleading to those who do not have detailed knowledge of the tissue involved. The TNM-classification for malignant tumours of the lip and oral cavity is also included.