MME and Burkitt lymphoma: The definition of Burkitt lymphoma (BL) in WHO-HAEM5 remains largely unchanged, describing BL as an aggressive mature B-cell neoplasm composed of medium-sized cells with a germinal center B-cell phenotype CD10+, BCL6+, BCL2-/weak, high Ki67 index (>95%) and an IG::MYC juxtaposition (Fig. 4).