MKI67 and Burkitt lymphoma: According to the World Health Organization (WHO) HAEM5 classification criteria, Burkitt lymphoma is defined as an aggressive mature B-cell neoplasm composed of medium-sized cells with a germinal center phenotype (CD10+, BCL6+, BCL2-), a high proliferative index (Ki-67>95%), and IG::MYC juxtaposition (8).