CLINICAL OBSERVATIONS, INTERVENTIONS, AND THERAPEUTIC TRIALS The Burkitt-like lymphomas: a Southwest Oncology Group study delineating phenotypic, genotypic, and clinical features

phoma classification gives Burkitt-like lymphoma (BLL) provisional status, leav-ing unresolved the differential diagnosis with Burkitt lymphoma (BL) and diffuse large B-cell lymphoma (DLBCL). This study compared the biologic features of adult BLL and DLBCL. The phenotypic distinction between BLL and DLBCL was determined by immunohistochemical staining of frozen tissue from 13 patients with BLL and 55 patients with DLBCL by using an extensive antibody panel includ-ing Ki-67, CD10, CD11a/lymphocyte func-tion–associated antigen 1a (LFA-1a), CD18/LFA-1b, CD58/LFA-3, and CD54/ intercellular adhesion molecule, CD8 for tumor-infiltrating cytotoxic T cells (T-TILs), CD44 homing receptor, and p53 and Bcl-2 oncogenic proteins. Compared with DLBCL, BLL had a higher prolifera-tive rate (mean Ki-67, 88 % versus 53%), greater expression of CD10 and p53 anti-gens, and decreased expression of Bcl-2. BLL cases had a consistent absence of one or more cell adhesion molecules (92% versus 27%), low T-TIL numbers, and ab-sence of CD44 homing receptor (92% versus 14%). The t(8;14) translocation was identified in 80 % of BLL cases, but no patients with BLL had the t(14;18) translocation. In a 10-year analysis, me-dian survival of patients with BLL was 1.2 years, and that of patients with DLBCL was 2.5 years. Although the proportion of patients cured was similar in the 2 groups, BLL patients had an increased risk of early death. We conclude that BLL can be recognized by its combined morphologic and phenotypic features and that it repre-sents a high-grade lymphoma much closer to BL than DLBCL. Retention of the BLL category or inclusion of BLL as a variant of BL is biologically and clinically more appropriate than absorbing the cat