B Cell Lymphomas

The classification of malignant lymphoma has always been a controversial subject, well-reflected in Rupert Willis’ statement, “nowhere in pathology has a chaos of names so clouded clear concepts as in the subject of lymphoid tumours” (Willis 1948). Despite the fact that non-Hodgkin’s lymphoma is at least twice as common as Hodgkin’s disease, it is interesting that this larger group of lymphoid neoplasms has not been given a name of its own but has come to be identified as so-called NOT or non-Hodgkin’s lymphomas. Terms like “reticulosis” and “reticulosarcoma” reflected prevailing concepts of the times and it was only in 1956 that the modern era of non-Hodgkin’s lymphoma (NHL) classifications began, with the publication of Rappaport’s classification (Rappaport et al. 1956). The Rappaport classification, based purely on morphological criteria, found favour among pathologists and clinicians alike for its relative simplicity and ease of application. General usage soon established the clinical relevance of this morphological classification. However, in the past two decades, developments in cellular immunology have led to radical changes in our concepts of the function and morphology of the lymphoid system. The accumulating information on the biology of lymphocytes resulted in objections to the validity of Rappaport’s terminologies and the concepts inherent in his classification. Within a short period some five major classifications for NHL were proposed. While three of these were based purely on morphological grounds (Bennett et al. 1974; Dorfman, 1974; Mathe et al. 1976), the classifications of Lukes and Collins (1974) and of Lennert (Gerard-Merchant et al. 1974; Lennert et al. 1975) were based on a functional or immunological approach.