The revised 4th edition of the WHO classification of haematolymphoid tumors (WHO-HAEM4R) introduced a category of “High-grade B-cell lymphoma, unclassifiable, with rearrangements of MYC and BCL2, and/or BCL6”, taking into account the inferior prognosis of neoplasms characterized by such dual or triple MYC, BCL2, and/or BCL6 rearrangements. The gene discussed is BCL6; the disease is B-cell non-Hodgkin lymphoma.