Differentiating DLBCL NOS from other LBCL types, particularly from DLBCL/high-grade B cell lymphomas (HGBL) with MYC/BCL2 rearrangements (double hit), typically involves morphological assessment, immunophenotyping, and fluorescence in situ hybridization (FISH) for BCL2, BCL6, and MYC rearrangements [9]. The gene discussed is BCL6; the disease is diffuse large B-cell lymphoma.