[Post-transfusion purpura].

Post-transfusion purpura (PTP) is a rare syndrome that may develop a week after blood transfusion. In this syndrome, which occurs mainly in women, blood transfusion is followed by severe thrombocytopenia a week later. A 72-year-old woman with this syndrome is presented. High-dose intravenous gamma-globulin resulted in prompt resolution of her thrombocytopenia. The basic pathophysiologic mechanism of PTP is the development of an alloantibody to a human platelet antigen. The mystery of PTP is why the patients' own, as well as transfused PLA1-negative platelets, are destroyed.