Diffuse large B‐cell lymphoma (Richter syndrome) in patients with chronic lymphocytic leukaemia (CLL): a cohort study of newly diagnosed patients

Summary Nearly all information about patients with chronic lymphocytic leukaemia (CLL) who develop diffuse large B‐cell lymphoma [Richter syndrome (RS)] is derived from retrospective case series or patients treated on clinical trials. We used the Mayo Clinic CLL Database to identify patients with newly diagnosed CLL between January 2000 and July 2011. Individuals who developed biopsy‐proven RS during follow‐up were identified. After a median follow‐up of 4 years, 37/1641 (2·3%) CLL patients developed RS. The rate of RS was approximately 0·5%/year. Risk of RS was associated with advanced Rai stage at diagnosis (P