High-grade B-cell lymphoma (HGBL) with MYC and Bcl-2 and/or Bcl-6 rearrangements is an aggressive mature B-cell lymphoma that harbours a MYC rearrangement at chromosome 8q24 and a rearrangement in Bcl-2 (at chromosome 18q21) and/or in Bcl-6(at chromosome 3q27). The gene discussed is BCL6; the disease is B-cell non-Hodgkin lymphoma.