Next‐generation sequencing revealed characteristic mutations associated with follicular lymphoma and its high‐grade transformation in each DLBCL/HGBCL‐MYC/BCL2, and also frequent variants in genes targeted by somatic hypermutation (SHM) in almost all DLBCL/HGBCL‐MYC/BCL2, DLBCL‐NOS, and HGBCL‐NOS but one case. The gene discussed is BCL2; the disease is follicular lymphoma.