doi:10.1111/bjh.16917engPrieto-Torres, LTrascasa, AManso, RMachan, SCieza-Diaz, DOlmedilla, GGarcia-Garcia, MAra-Martin, MRequena, LPiris, MARodriguez-Pinilla, SMTwo independent consecutive lymphoma cases carry an identical MYD88 mutation but differ in their IGVH rearrangementART-2020-118932Several studies have provided evidence of the presence of lymphoma stem cells by showing the apparent transmission of premalignant lymphoid cells in allogeneic bone marrow transplantation, where the donor and recipient develop the same lymphoid disease.1-6 The lymphoid neoplasms do not develop at the same time, and in some cases, a different immunoglobulin heavy chain (IgH) rearrangement occurs in the two tumours. These data support the theory of a common lymphoma precursor cell (CPC) and make it less likely that it is due to a circulating donor tumour cell. Recently, Hattori et al.7 published genetic evidence of CPC in primary central nervous system diffuse large B-cell lymphoma (PCNS-DLBCL), suggesting that intra- and extra-CNS tumours in the same patient are derived from CPC with myeloid differentiation factor 88 (MYD88) L265P gene mutations, which arise before or after the IgH rearrangement. They suggested that CPC maps to different positions during B-lineage differentiation. The position after IgH rearrangement and even after hypermutation at the variable region could explain the appearance of clonally related lymphomas, whereas the emergence of CPC before IgH rearrangement might account for the presence of clonally unrelated B-cell lymphomas in the same patient because divergence may occur before the Variable-Diversity-Junctional (VDJ) rearrangements.2020http://zaguan.unizar.es/record/15665710.1111/bjh.16917http://zaguan.unizar.es/record/156657oai:zaguan.unizar.es:156657info:eu-repo/grantAgreement/ES/ISCIII/PI17-01294info:eu-repo/grantAgreement/ES/ISCIII/PI17-02172info:eu-repo/grantAgreement/ES/MINECO-RTICC-ISCIII-CIBERONC/PIE15-0081info:eu-repo/grantAgreement/ES/MINECO-RTICC-ISCIII-CIBERONC/RD06-0020-0107-RD012-0036-0060info:eu-repo/grantAgreement/ES/MINECO-RTICC-ISCIII-CIBERONC/SAF2013-47416-RBRITISH JOURNAL OF HAEMATOLOGY 190, 6 (2020), e352-e356by-nchttps://creativecommons.org/licenses/by-nc/4.0/deed.esinfo:eu-repo/semantics/openAccess