Management of CLL patients with Richter transformation to diffuse large B-cell lymphoma in which no clinical trial is available.¶The simplest way to determine clonality is to compare the κ and λ light chain restriction between the CLL and the DLBCL. For patients in whom they are different (eg, κ light chain–restricted CLL and λ light chain–restricted DLBCL), DLBCL is clonally unrelated to the CLL. In those patients in whom the light chain restriction is the same, clonality is determined either by sequencing the IGHV V-D-J genes or by comparing immunoglobulin gene rearrangements between the CLL and DLBCL tissue samples. *Consider a platinum-containing regimen for patients with prior anthracycline exposure. We generally administer pegfilgrastim to all patients undergoing intensive chemotherapy for RS. §Age, functional status, comorbidities, and chemosensitive disease determine if patient is a suitable candidate for stem cell transplantation. ¶¶Both autologous and allogeneic SCT may play a role in improving durability of remission. Factors that influence whether autologous or allogeneic is preferred strategy include patient age/fitness, availability of a suitable donor, the presence or absence of del(17p13.1)/TP53 mutation, and whether the patient’s underlying CLL is purine analog refractory. **An allogeneic stem cell transplantation is preferred in patients with clonally related RS as well as those with clonally unrelated DLBCL whose underlying CLL is purine analog–refractory or harbors the del(17p13.1)/TP53 mutation. §§Autologous SCT is our preferred approach for patients with clonally unrelated DLBCL whose CLL does not harbor the del(17p13.1)/TP53 mutation. An autologous SCT may be considered in select patients with clonally related RS who do not have a suitable donor or who are not candidates for allogenic SCT based on age/comorbidity. The primary intent of autologous SCT in such cases is to eradicate the DLBCL component rather than simultaneously treat the underlying CLL. ¶¶¶At this time, outside of a clinical trial, there are no specific recommendations for a postremission strategy among patients with clonally related RS who demonstrate a response to induction chemotherapy and are not considered candidates for SCT.