IRF4 and diffuse large B-cell lymphoma: Thus, in a case with ABC type DLBCL (DLBCL #6), the exosomal mRNA expression at diagnosis, such as BCL2, IRF4, and MYC, were persistent even after the completion of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine) chemotherapy, and it was consistent with the PET-CT findings showing a newly appeared lesion at the end of treatment.