Duffield, Amy S.Dogan, AhmetAmador, CatalinaCook, James R.Czader, MagdalenaGoodlad, John R.Nejati, RezaXiao, WenbinHapp, LanieParker, ClayThacker, ElizabethThakkar, DevangDave, Sandeep S.Wasik, Mariusz A.Ott, German2024-08-032024-08-032023-05-11Duffield AS, Dogan A, Amador C, et al. Progression of follicular lymphoma and related entities: Report from the 2021 SH/EAHP Workshop. Am J Clin Pathol. Published online May 11, 2023. doi:10.1093/ajcp/aqad042https://hdl.handle.net/1805/42593Objectives: The 2021 Society for Hematopathology and European Association for Haematopathology Workshop addressed the molecular and cytogenetic underpinnings of transformation and transdifferentiation in lymphoid neoplasms. Methods: Session 4, "Transformations of Follicular Lymphoma," and session 5, "Transformations of Other B-Cell Lymphomas," included 45 cases. Gene alteration analysis and expression profiling were performed on cases with submitted formalin-fixed, paraffin embedded tissue. Results: The findings from session 4 suggest that "diffuse large B-cell lymphoma/high-grade B-cell lymphoma with rearrangements of MYC and BCL2" is a distinct category arising from the constraints of a preexisting BCL2 translocation. TdT expression in aggressive B-cell lymphomas is associated with MYC rearrangements, immunophenotypic immaturity, and a dismal prognosis but must be differentiated from lymphoblastic -lymphoma. Cases in session 5 illustrated unusual morphologic and immunophenotypic patterns of transformation. Additionally, the findings support the role of cytogenetic abnormalities-specifically, MYC and NOTCH1 rearrangements-as well as single gene alterations, including TP53, in transformation. Conclusions: Together, these unique cases and their accompanying molecular and cytogenetic data suggest potential mechanisms for and unusual patterns of transformation in B-cell lymphomas and indicate numerous opportunities for further study.en-USPublisher PolicyTdTDiffuse large B-cell lymphomaFollicular lymphomaHigh-grade B-cell lymphomaLymphoblasticTransformationArticle