Unusual Aspects of the Epidemiology of

Autoimmune hemolytic anemia (AIHA) is most often idiopathic. However, in recent years, AIHA has been noted with increased incidence in patients receiving purine nucleoside analogues for hematologic malig-nancies; it has also been described as a complication of blood transfusion in patients who have also had alloimmunization. As the technology of hematopoietic stem cell transplantation has become more wide-spread, immune hemolysis in the recipients of ABO-mismatched products has become better recog-nized. The syndrome is caused by passenger lymphocytes transferred from the donor and, although transient, can be quite severe. A similar syndrome has been observed in recipients of solid organ trans-plants when there is ABO-incompatibility between donor and recipient. Venous thromboembolism is a little-recognized, though likely common, complication of AIHA, and may in some instances be related to coexistent antiphospholipid antibodies. While AIHA is a well-docu-mented complication of malignant lymphoproliferative disorders, lymphoproliferative disorders may also paradoxically appear as a consequence of AIHA. A number of newer options are available for treatment of AIHA in patients refractory to corticosteroids and splenectomy. Newer immunosuppressives such as mycophenolate mofetil may have a role in such cases. Considerable experience has been accumulating in the last few years with monoclonal antibody therapy, mainly rituximab, in difficult AIHA cases; it appears to be a safe and effective option