Origin of high-grade lymphomas in Richter syndrome

Patients with B cell chronic lymphocytic leukemia (CLL) occasionally develop high-grade B cell lymphomas that are associated with constitutional symptoms, rapidly progressive lymphadenopathy, and swift clinical deterioration. Now known as Richter syndrome, this symptom complex develops in approximately 5% of all patients with CLL. Structural and molecular analysis of the immunoglobulin (Ig) genes have allowed investigators to define the clonal relationship between the leukemia and lymphoma cells of a given patient. In most cases the aggressive lymphoma evolves from the original leukemia cell clone. However, in some cases the lymphoma apparently represents a second malignancy. Differentiation between these two types of lymphoma may have clinical significance. Further investigation is required to allow for identification of CLL patients who are at risk for developing Richter syndrome and to understand factors involved in its etiopathogenesis.