¹⁸FDG-PET/CT Demonstrates High Accuracy in Identifying Richter's Transformation from Chronic Lymphocytic Leukemia in Clinically Suspected Patients

Objectives To evaluate the usefulness of [¹⁸F]fluorodeoxyglucose positron-emission tomography/computed tomography (¹⁸FDG-PET/CT) in identifying Richter’s transformation from chronic lymphocytic leukemia (CLL).

Methods 56 consecutive patients with clinically suspected Richter’s transformation underwent ¹⁸FDG-PET/CT at our institution between April 2008 and December 2013. Nodal/viscera plus bone marrow biopsies were performed within two weeks following ¹⁸FDG-PET/CT. The features of ¹⁸FDG uptake were correlated with histology findings and clinical presentation of disease retrospectively. Furthermore, all patients with Richter’s transformation, including 29 patients with diffuse large B cell lymphoma (DLBCL) and 2 Hodgkin’s lymphoma (HL) had subsequently 78 ¹⁸FDG-PET/CT studies to assess response to treatment, over an average follow-up period of 17 months.

Results For diagnosis, apart from 1 patient with small infraorbital cutaneous DLBCL, ¹⁸FDG-PET/CT identified all other 28 DLBCL and 2 HL. Of note, 25 of these 30 patients showed only localised transformation, typically with high grade ¹⁸FDG avid lesions being identified in the background of generalised low grade ¹⁸FDG avid lymphoadenopathy. Post-chemotherapy, whilst ¹⁸FDG-PET/CT demonstrated complete response at transformation sites in 28 of 31 patients, CLL associated generalised lymphoadenopathy persisted in 16 of them. ¹⁸FDG-PET/CT also detected 1 metastatic bladder cancer and 1 prostate cancer, respectively. However, none of the other 23 CLL patients showed suspicious lesions to suggest transformation despite indifferent clinical presentations.

Conclusions ¹⁸FDG-PET/CT demonstrates high accuracy in identifying the usually localised Richter’s transformation at its early onset and, it is also a reliable tool in assessing response to treatment in this heterogeneous group of patients requiring newer treatments.