IHC performed on the cell block showed positive staining for CD20 (L26, Ventana), PAX-5 (1EW, Leica), Ki67 (MIB-1) (K2, Leica) in 80–90% cells and negative staining for CD3 (SP7, Thermo Scientific), Myc (Y69, Abcam), BCL-2 Oncoprotein (124, Ventana), EBER ISH (ISH5687-A, Leica) and CD138 (M115, Leica); indicating a large B-cell lymphoma with a differential diagnosis of high grade B-cell lymphoma versus DLBCL. The gene discussed is MKI67; the disease is diffuse large B-cell lymphoma.