Principles of the pathology and biology of malignant lymphomas

Abstract

The lymphoma classification currently in use, the fourth edition of the WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues (Swerdlow SH et al, (eds) WHO classification of tumours of haematopoietic and lymphoid tissues, 4th edn. IARC, Lyon, 2008), is founded on the basic principles of the Revised European American Lymphoma (REAL) Classification of 1994 (Harris NL et al, A revised European-American classification of lymphoid neoplasms: a proposal from the International Lymphoma Study Group. Blood 84:1361-1392, 1994). These principles, however, had been recognized earlier. Divergent and conflicting proposals for lymphoma classifications had been formulated in the 1970s, resulting in the emergence of two classification systems widely used: the Kiel classification of non-Hodgkin’s lymphomas (Stansfeld, et al, Updated Kiel classification for lymphomas. Lancet I: 292-293, 603, 1988) and the working formulation for clinical usage (WF; Non-Hodgkin’s lymphoma pathologic classification project 1982). Both classification systems relied upon entirely different principles. The Kiel classification was based on the exact morphological description and (later) immunological identification of the normal cellular counterparts of tumor cells and was updated several times.