IRF4 and diffuse large B-cell lymphoma: A 78-year-old male patient was diagnosed with DLBCL (GCB, stage IV) in July 2021 according to the IHC analysis of parotid gland biopsy showing CD19 (+), CD20 (+), CD3 (-), CD5 (-), CD10 (-), CD45 (+), BCL2 (-), BCL6 (+), MUM1 (-), MYC (+) and Ki-67 (+, 90%).