BCL6 and Burkitt lymphoma: In a gene expression profile study of human samples of BL (and DLBCL), three main cytogenetic groups within the mature aggressive B cell lymphomas were distinguished: MYC-simple, with IG-MYC fusions and a low chromosomal complexity score, no IGH-BCL2 fusions, and no BCL6 breakpoints, and with a favorable prognosis; MYC-complex, including IG/MYC-rearranged BLs with highly complex karyotypes, non-IG/MYC-rearranged cases, and all IGH/BCL2 fusions and/or BCL6 breakpoints, or any combination of these; and MYC-negative, comprising lymphomas with unaltered MYC [127].