[New WHO-classification of lung and pleural tumors]

A new classification of the World Health Organization (WHO) of lung and pleural tumours will be published presently. Compared with the previous edition of 1981 the changed parts more accurately reflect the available therapeutic choices and the prognostic characteristics of the different tumour types. The classification is based on conventional light-microscopical typing. Additional techniques (from histochemistry, immune histochemistry, electron microscopy and molecular biology) have not yet decisive influence on tumour typing. The dichotomy between small-cell and large-cell carcinomas is too simplistic, as the group of large-cell carcinomas is heterogeneous, and further differentiation leads to identification of tumour types with distinct therapeutic options and prognostic characteristics. There are new criteria for the classification of neuroendocrine tumours, such as the mitotic index. It is recommended to use the newly revised classification for diagnostic purposes, epidemiology and biologic studies.