The diagnosis of high-grade transformation (HGT) from indolent B-cell non-Hodgkin lymphoma (iBNHL) remains a significant clinical challenge in the management of patients with lymphoid neoplasms.[[1]] Although HGT can be subjectively suspected based on symptoms or imaging ("disproportionate" volume change, morphological change), these features are not specific for the diagnosis.[[3], [5], [7]] While 2-deoxy-2-[ 18F] fluoro-D-glucose (FDG) PET can be useful to detect Richter transformation in CLL by identifying a representative biopsy site,[9] PET does not differentiate iBNHL from HGT in the vast majority of lymphoma histological categories, and, paradoxically, follicular lymphoma (FL), the commonest iBNHL, can demonstrate high standard uptake values (SUV) on PET.[2] Histology remains the gold standard required to diagnose HGT; however, selection of a suitable biopsy site for possible HGT is often challenging in patients. GLO:1XW/15may20:bjh16580-fig-0001.jpg PHOTO (COLOR): 1 (a) Colour-fused PET-CT image showing focal splenic involvement (blue arrow); splenic lesion biopsy proven to reflect DLBCL HGT in a patient with known FL. 39 patients had one or more documented splenic lesions on imaging out of 390 patients in total. [Extracted from the article]