Wendy Osborne, Hannah Bielby, Kate Cwynarski, Dima El-Sharkawi, George Petrides, Timothy Illidge, N George Mikhaeel, Cathy Burton, Amos Burke, Mary Gleeson, Christopher P Fox, Andrew Davies, BSH Committee
Primary mediastinal B-cell lymphoma (PMBCL) is a distinct clinicopathological entity within the spectrum of aggressive B-cell lymphomas, characterised by unique clinical, immunophenotypic and molecular features. Since publication of the 2019 British Society for Haematology (BSH) Good Practice Paper, there have been important advances in imaging, radiotherapy approaches and systemic therapies, including chimeric antigen receptor (CAR) T-cell therapy and immune checkpoint inhibition. Key updates include the use of PET-adapted approaches to guide radiotherapy decisions following first-line chemoimmunotherapy, with omission of consolidative radiotherapy in patients achieving complete metabolic response. The guideline emphasises the importance of dose-intensive chemoimmunotherapy regimens and provides a framework for the clinical management of patients with Deauville stage 4 (DS4) and DS5 response status on PET-CT imaging following chemoimmunotherapy.