CD79B and diffuse large B-cell lymphoma: The MCD subtype of DLBCL was identified by next-generation sequencing of the lymph node at initial diagnosis characterized by co-occurring point mutations in <i>MYD88</i> <sup><i>L265P</i></sup> and <i>CD79B.</i> Additionally, two different dominant clonotypes of the immunoglobulin heavy chain (<i>IGH</i>) were detected in the lymph node and BM by <i>IGH</i> sequencing, which was <i>IGHV</i> 3-11*06/<i>IGHJ</i> 3*02 and <i>IGHV</i> 3-11*06/<i>IGHJ</i> 6*02, respectively, speculating to be two independent clonal origins.