Using exome and targeted sequencing, our work uncovers for the first time, the mutational landscape of grey zone lymphoma (GZL). The study, which was led by Clementine Sarkozy, highlights distinct mutational profiles between thymic and non-thymic GZL, and the unique landscape of poly-EBV-L. These results suggest distinct cells-of-origin and modes of disease evolution within the GZL spectrum.