Authors' reply.

Sir,

We thank Dr. Joob for showing interest in our case.[1] We described a case of thrombotic thrombocytopenic purpura (TTP) after transfusion of ABO incompatible blood in a heart surgery patient. To the best of our knowledge, there is no report of TTP after erroneous blood transfusion. ABO incompatible blood organ transplantation is performed after desensitization of the recipient through plasmapheresis and intravenous immunoglobulin. Thus, ABO incompatibility may not play a direct role in that setting. On the other hand calcineurin inhibitors, well-defined etiologic factors for development of TTP, might have played a role there. We also generated a pathophysiologic hypothesis in our case report. There was no clinically overt cancer but cannot rule out an occult malignancy.