Richter's syndrome following cladribine therapy for chronic lymphocytic leukemia first manifested as pathologic fracture of the femur.

Richter's syndrome (RS) refers to the development of aggressive non-Hodgkin's lymphoma (NHL) during the course of chronic lymphocytic leukaemia (CCL). It occurs in approximately 3% of patients with CLL. The isolated form of this complication in bone is extremely rare and, so far, has not been described in a patient treated with cladribine (2-CdA). We report a case of CLL treated successfully with 2-CdA, where isolated diffuse large B-cell lymphoma (LBCL) developed 2 years after the diagnosis of CLL Rai II and one year after the completion of 2-CdA treatment. RS was first manifested as a pathologic fracture of the left femur. The LBCL was clonally distinct from the original CLL cells. The patient was successfully treated with CHOP and radiotherapy and obtained complete response of the LBCL.