A second case of post-transfusion purpura caused by HPA-5a antibodies: successful treatment with intravenous immunoglobulin.

Post-transfusion purpura (PTP) is a rare disorder characterized by severe thrombocytopenia developing seven to 10 days following transfusion of platelet-containing blood components, in a person who was previously sensitized via transfusion or pregnancy. Although most cases of PTP are caused by alloantibodies directed against HPA-1a[(Pl(A1))], this case represents the second example of anti-HPA-5a-associated PTP. A 61-year-old female was diagnosed with acute myocardial infarction and gastrointestinal bleeding and, after receiving six units of packed red cells over 5 days, developed PTP as a result of HPA-5a [Br(b)] antibodies with severe thrombocytopenia (5000/microl). She was successfully treated with intravenous immunoglobulin (IVIG), suggesting that this is a highly effective mode of treatment for PTP, regardless of the antibody implicated.