We identified highly recurrent oncogenic mutations in the Janus kinase-signal transducer and activator of transcription and nuclear factor κB pathways, and provide additional evidence of the importance of immune evasion in PMBL (<i>CIITA, CD58, B2M, CD274,</i> and <i>PDCD1LG2</i>).
In summary, we establish CIITA alterations as a common mechanism of immune escape through reduction of MHC class II expression in PMBCL, with potential implications for future treatments targeting microenvironment-related biology.