Burkitt lymphoma and atypical Burkitt or Burkitt-like lymphoma: should these be treated as different diseases?

Burkitt lymphoma (BL) is a mature B-cell non-Hodgkin lymphoma with an aggressive clinical course. Since the advent of short, intensive, multiagent chemoimmunotherapy regimens, it has carried a favorable prognosis. BL has been rather well characterized, whereas the other lymphomas morphologically resembling it are more heterogeneous. The cases classified as atypical BL/Burkitt-like lymphoma by the 2001 World Health Organization (WHO) Classification of Tumors of Hematopoietic and Lymphoid Tissue were thought to represent a continuum between BL and diffuse large B-cell lymphoma (DLBCL). The optimal therapeutic strategy for this provisional entity was not definitively established. However, recent incorporation of molecular genetic data into the 2008 WHO Classification has allowed further refinements with significant therapeutic implications, including the designation of a new provisional entity, "B-cell lymphoma, unclassifiable, with features intermediate between BL and DLBCL." This review presents a comprehensive overview of the previously designated provisional entity of atypical BL/BLL in conjunction with a detailed comparison with BL and DLBCL.