Mottok et al. [27] analyzed 45 primary mediastinal B cell lymphomas (PMBCL) and 3 PMBCL-derived cell lines for the presence of genetic alterations involving the major histocompatibility complex (MHC) class II transactivator CIITA and found frequent aberrations consisting of structural genomic rearrangements, missense, nonsense, and frame-shift mutations (53 % of primary tumor biopsies and all cell lines). This evidence concerns the gene CIITA and B-cell non-Hodgkin lymphoma.