Using gene expression profiling, our work provides a comprehensive phenotypic characterization of Grey Zone Lymphoma (GZL), highlighting the importance of tumor microenvironment biology and macrophage infiltration. The study, which was led by Clementine Sarkozy, confirms and further characterizes the existence of two groups of GZL with presumably distinct cells of origin and evolutionary modes, as well as highlighting key differences compared to polymorphic-EBV-L.