Lymphoma classification--the gap between biology and clinical management is closing.

EW INSIGHTS into the pathogenesis of lymphoid maN lignancies have been gained by novel techniques such as genetic, molecular, and immunologic methods and have not only broadened our knowledge about the origin and development of malignant lymphomas, but also have substantial clinical implications. Hence, distinct disorders can be defined more precisely and therapeutic strategies may be directed more specifically to well-defined lymphoma entities. The closing gap between a better understanding of lymphoma biology and its translation into the clinical management of lymphoid malignancies requires an appropriate adaptation of histopathologic classification and clinical grouping and stimulates the reflection and reassessment of previously developed and newly proposed classification systems. Over the past 40 years, the challenge of adaptation to new knowledge and novel techniques has reappeared several times and has prompted reconsideration of the classification and clinical grouping of malignant lymphomas from time to time. The process of reconsideration has regularly followed a sequence of steps which comprise the proposal of a new classification, its evaluation and testing, its acceptance and broad application or rejection, respectively, and finally its revision and modification as new information is gained (Fig 1). Two years ago, a new histopathologic classification for neoplasms of the lymphoid lineage was proposed by the International Lymphoma Study Group.’ It emerged from the joint efforts of an international group of pathologists who tried to adapt the categorization of malignant lymphomas to the present status of knowledge and techniques. The first step of a new classification system was, therefore, signaled by the appearance of the “Revised European American Lymphoma” schema which has now entered the subsequent stages of evaluation and testing.’ At the second anniversary of its publication in Blood, it seems appropriate to consider the general concept of the “Revised European American Lymphoma’ ’ classification, its potential clinical application and perspective, as well as its differences from preceeding groupings.