Classification of Non-Hodgkin's Lymphoma: A Proposal

Abstract

The pathology community has traditionally classified the non-Hodgkin's lymphomas (NHL) according to their histogenetic characteristics, an approach that has fostered the proliferation of multiple, often conflicting, lymphoma classification schemes with limited clinical relevance. The scientific acceptance of these histogenetically pure schemes is based on an implicit belief that all that is scientifically sound must adhere to linear dynamic theory; that is, that the elemental components of a system in a linear and direct fashion control the behavior of the whole. Non-linear dynamic theory, however, which has recently acquired acceptance within the scientific community, offers another equally valid approach to the classification of the NHL by acknowledging the inherent indeterminacy of nature. In other words, rather than classifying the NHL according to their cell of origin in the hopes that the elemental unit will predict the clinical outcome, we propose that pathologists accept the premise that nature is inherently unpredictable and define the NHL according to their clinical characteristics, such as natural history and response to therapy. Using these criteria, a proposed classification is discussed containing two major subtypes of lymphomas (indolent and aggressive) which can be further subdivided into five groups: the low-grade, or indolent, group includes the small lymphocytic and the follicular cleaved cell (small, and small, mixed) categories, while the high-grade, or aggressive, group includes the large-cell, the Burkitt's lymphoma, and the lymphoblastic lymphomas. Each of these groups is discussed in detail, with comparisons to the Revised European American Lymphoma classification to demonstrate clinical relevance. Although it is clear to us that the proposed scheme presented in this manuscript is not the only clinically valid one that can be constructed, it is equally clear that any scheme that is developed-in order to be considered valid-must be guided principally by its clinical relevance.