Post-transfusion purpura: initiation by leukocyte-poor red cells in a polytransfused woman.

An elderly, multiparous, multiply transfused woman developed post-transfusion purpura (PTP) after the transfusion of 2 units of leukocyte-poor red cells and was successfully treated by plasmapheresis and corticosteroids. Her pre-PTP transfusion history was characterized by frequent, multiple transfusions of platelet antigen-containing blood products 12 to 5.5 years prior to the onset of disease and, apart from the initiating transfusion, only frozen red cells in the 5.5 years immediately preceding the onset of thrombocytopenia. Leukocyte-poor red cells thus appear capable of initiating PTP. Use of a few units of frozen red cells may result in a shorter than normal refractory period, after which time PTP may occur upon exposure to sufficient platelet antigen.