ABSTRACT
Introduction 295 Conceptual basis of classification 296 Basic units of classification 297 Entity 297 Prognostic factor 297 Variant 298 Functional aspects of classification 298 Normal counterpart/differentiation arrest 298 Stem cell concept 299 Clonal evolution 301 Etiology and pathogenesis 301 Principles and methods of classification 302 Morphology/histopathology 302 Immunohistochemistry 303
Genetic features 304 Clinical presentation 305 Classification of major entities of lymphoproliferative 305
disorders Precursor neoplasms 309 Mature B cell lymphoma 309 Mature T/natural killer cell lymphoma 310 Hodgkin lymphoma 310 Plasmacytoma/multiple myeloma 310 Lymphoproliferative disorders in immunocompromised 311
patients Early stages/precursor lesions 311 Key points 311 References 312
Classification of tumors is a major task of diagnostic pathology. Rudolf Virchow, 110 years ago, wrote in a conceptual speech on the anatomic understanding of disease and the tasks of pathologic research:1 ‘The research on the origin of diseases (the Latin “sedes morbi,” quoting the famous book of Morgagni: De sedibus et causibus morborum2) has progressed from organs to tissues and from tissues to cells.’ If we were to continue this reasoning today, we would complete the phrase: ‘from cells to molecules and pathways.’ This basic and functional understanding of biologic processes should govern the ideas of modern tumor classification – it still remains an idealistic goal, not reached in all tumor subtypes and hard to achieve in the individual diagnostic process.
