Given the distinct cell of origin between TdT‐positive DLBCL/HGBCL and B‐ALL/LBL and potential differences in their mutation profiles, we investigated somatic mutations in both rearranged IGHV genes and lymphoma genes (n = 187) by targeted next‐generation sequencing (NGS) and performed integrated analysis to explore their utility in differential diagnosis. The gene discussed is DNTT; the disease is diffuse large B-cell lymphoma.