In this paper, the authors evaluate the historical evolution of the definition of Burkitt's lymphoma (BL) and of its clinicoepidemiological (endemic, sporadic, and acquired immunodeficiency syndrome-associated BL) and morphological variants. On the basis of the morphological, immunologic, genetic, and clinical characteristics of these tumors, the authors also emphasize the importance of precise disease definitions for biological and epidemiological studies. These principles were used in accordance with the Revised European-American classification of lymphoid neoplasms (REAL), which proposed that disease entities should be defined by a constellation of pathobiological and clinical features.
