Case Report: Clonal evolution of diffuse large B-cell lymphoma to plasmablastic lymphoma: diagnostic challenges in a case of gastric lesion with EBV-negative PBL

For extranodal lymphomas, multisite sampling should be performed for a confirmed diagnosis to prevent misdiagnosis or oversight of concurrent lesions. This diagnostically challenging case highlights the importance of molecular testing for identifying and understanding the clonal evolution of lymphomas and suggests how immunophenotypic heterogeneity may lead to misdiagnosis. It also provides important insights into the biology of DLBCL-to-PBL evolution. These findings highlight the need for more precise molecular diagnostic tools and novel approaches to improve outcomes for patients with such highly aggressive lymphoma.