The problem of classifying lymphomas: An orderly prescription for progress

Abstract

In the late 1960s and early 1970s, the most widely recognized 'new' classifications of the non-Hodgkin's lymphomas were those proposed by Rappaport (the 'Rappaport' classification) and by Lennert (the 'Kiel' classification). With the advent of immunologic and histochemical markers in the early 1970s, however, new concepts arose to supplement the traditional purely morphologic approach to diagnosis and classification of these tumors. Lymphomas were increasingly recognized to be neoplasms of the immune system, composed of malignant proliferations which retained many of the morphologic and functional characteristics of their normal counterparts. These advances led to a flurry of new classifications proposed in 1974-1976, leading to confusion for both clinicians and pathologists, perhaps most evident at the International Cancer Congress in Florence in 1974. To address this problem, the National Cancer Institute (USA) sponsored an international workshop of expert pathologists and clinicians on 4-5 September 1975. It became apparent at that meeting that only a well-planned retrospective study would provide data for meaningful progress and resolution of differences. From 1976 to 1980, such a massive collaborative project was accomplished and served as the basis for the Working Formulation for Clinical Usage, proposed as a vehicle for translation among the six tested schema. Since the Working Formulation was published in 1982 there have been momentous strides in scientific and clinical understanding of these cancers, fueled by contributions from immunology, cytogenetics, and molecular biology. To recognize and disseminate understanding of these newer observations, the International Lymphoma Study Group promulgated in 1994 a new proposal entitled 'A Revised European-American Classification of Lymphoid Neoplasms'. As a sequel to another international assembly of pathologists and clinicians, held at the National Cancer Institute (USA) on 21-23 March 1994, a second large-scale retrospective study has been accomplished, the results of which were presented at the Sixth International Conference on Malignant Lymphoma, 5-8 June 1996, along with data from other institutions and cooperative groups. Concurrent with these events, the World Health Organization has enlisted a committee of expert pathologists to prepare a new edition of 'Neoplastic Diseases of Hematopoietic and Lymphoid Tissues'. Composed of 10 pathology subcommittees and a clinical advisory committee, with broad international representation, this body should generate in the near future a consensus proposal with broad scientific and geographic support. These historical and ongoing efforts in lymphoma pathology are a paradigm for progress in clinicopathologic understanding of all cancers.