IRF4 and diffuse large B-cell lymphoma: LBCL-IRF4 is a very infrequent neoplasm accounting for 0.05% of diffuse large B-cell lymphomas [2]; it primarily affects children and young adults with a median age of 12 years [2,116] and is characterized by a strong expression of IRF4/MUM1 and frequent IRF4 rearrangement [2].