[Classification of neoplastic disorders of the haematopoietic system]

The present article is written in an attempt to illustrate the ongoing diagnostic progress by presenting some examples of pre-existing and newly defined entities. The World Health Organisation proposed in 2001 a "Classification of Tumours of the Haematopoietic and Lymphoid Tissues". Relying on the broadest consensus possible, it received high acclamation by both clinicians and pathologists. The approach is based on cell lineage assignment including morphology and immunophenotype, but also relies on cytogenetic and clinical features in order to define disease entities to an extent as far as possible. The diagnostic criteria for myeloid, lymphoid and histiocytic neoplasms have been compiled by an international group of 51 experts assembled in ten disease-related committees. In order to cover the interests of daily haematological practice, selected topics are focussed including chronic and acute myeloid neoplasias, precursor lymphoid neoplasias, mature B-, T- and NK-cell lymphomas, Hodgkin lymphoma as well as histiocytic and dendritic cell neoplasias.