Questionable efficacy of plasma exchange for thrombotic thrombocytopenic purpura after bone marrow transplantation

Thrombotic thrombocytopenic purpura (TTP) after bone marrow transplantation (BMT) is an uncommon complication presumably associated with extensive endothelial cell damage due to Cyclosporine, total body irradiation, or other drugs. While the majority of patients with primary TTP, which is considered to be an autoimmune process, respond to plasma exchange, TTP after BMT has a very poor prognosis. A total of 7 patients out of 307 patients who underwent BMT were diagnosed with TTP during 1989-1999. The diagnosis of TTP was made based on thrombocytopenia and microhemangiopathic hemolytic anemia characterized by an elevated LDH and the presence of schistocytes on the peripheral blood smear. Five patients were treated with plasma exchange (PE) using fresh frozen plasma and/or cryoprecipitate poor plasma as replacement fluid. One patient was treated using a protein A column. One patient did not receive plasma exchange because the 125 patient was clinically stable and was discharged. It was hard to assess the efficacy of PE due to the multiplicity of the patients' clinical condition and laboratory data. At least 4 patients did not respond to PE and 2 patients were not able to be evaluated due to multi organ failure. However, all patients died. It is not clear at this moment if PE for patients with TTP after BMT is truly beneficial.