THE PROBLEM OF CLASSIFYING LYMPHOMAS - AN ORDERLY PRESCRIPTION FOR PROGRESS

In the late 1960s and early 1970s, the most widely recognized 'new' cl assifications of the non-Hodgkin's lymphomas were those proposed by Ra ppaport (the 'Rappaport' classification) and by Lennert (the 'Kiel' cl assification). With the advent of immunologic and histochemical marker s in the early 1970s, however, new concepts arose to supplement the tr aditional purely morphologic approach to diagnosis and classification of these tumors. Lymphomas were increasingly recognized to be neoplasm s of the immune system, composed of malignant proliferations which ret ained many of the morphologic and functional characteristics of their normal counterparts. These advances led to a flurry of new classificat ions proposed in 1974-1976, leading to confusion for both clinicians a nd pathologists, perhaps most evident at the International Cancer Cong ress in Florence in 1974. To address this problem, the National Cancer Institute (USA) sponsored an international workshop of expert patholo gists and clinicians on 4-5 September 1975. It became apparent at that meeting that only a well-planned retrospective study would provide da ta for meaningful progress and resolution of differences. From 1976 to 1980, such a massive collaborative project was accomplished and serve d as the basis for the Working Formulation for Clinical Usage, propose d as a vehicle for translation among the six tested schema. Since the Working Formulation was published in 1982 there have been momentous st rides in scientific and clinical understanding of these cancers, fuele d by contributions from immunology, cytogenetics, and molecular biolog y. To recognize and disseminate understanding of these newer observati ons, the International Lymphoma Study Group promulgated in 1994 a new proposal entitled 'A Revised European-American Classification of Lymph oid Neoplasms: As a sequel to another international assembly of pathol ogists and clinicians, held at the National Cancer Institute (USA) on 21-23 March 1994, a second large-scale retrospective study has been ac complished, the results of which were presented at the Sixth Internati onal 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 expe rt pathologists to prepare a new edition of 'Neoplastic Diseases of He matopoietic and Lymphoid Tissues: Composed of 10 pathology subcommitte es and a clinical advisory committee, with broad international represe ntation, this body should generate in the near future a consensus prop osal with broad scientific and geographic support. These historical an d ongoing efforts in lymphoma pathology are a paradigm for progress in clinicopathologic understanding of all cancers.