Richter's syndrome after allogeneic stem cell transplantation for chronic lymphocytic leukaemia successfully treated by withdrawal of immunosuppression, and donor lymphocyte infusion.

Development of high-grade non-Hodgkin's lymphoma is a possible complication of chronic lymphocytic leukaemia/small lymphocytic lymphoma, known as Richter's syndrome (RS). Treatment for RS includes systemic chemotherapy and, recently, allogeneic stem cell transplantation (SCT). We describe a patient with B-chronic lymphocytic leukaemia who developed RS 4 months after allogeneic SCT from an HLA-identical sibling. The RS presented with systemic symptoms, lymphadenopathy, pancytopenia and serum lactate dehydrogenase elevation. The patient was treated with immunosuppressive drug withdrawal and a donor lymphocyte infusion (DLI) of 1 x 10(7) CD3/kg, leading to the disappearance of all symptoms and the attainment of complete donor chimerism. After 18 months of the therapeutic DLI, the patient continues in complete remission.