By investigation of a spectrum of TdT‐positive B‐cell lymphomas including DLBCL/HGBCL‐MYC/BCL2, DLBCL‐NOS, HGBCL‐NOS, B‐ALL/LBLs, and cases unclassified, the present study has highlighted several points that would aid the differential diagnosis between TdT‐positive DLBCL/HGBCL and B‐ALL/LBL. Here, MYC is linked to acute lymphoblastic leukemia.