Idiopathic thrombocytopenic purpura during remission of thrombotic thrombocytopenic purpura.

Three patients were treated empirically with anti-platelet agents, prednisone, plasmapheresis, and prostacyclin for the classical clinical syndrome of thrombotic thrombocytopenic purpura (TTP). All three patients initially responded, then relapsed after one to 13 months with a clinical picture characteristic of immunogenic thrombocytopenic purpura (ITP). At relapse, all three had thrombocytopenia without microangiopathy or other causes of thrombocytopenia. All responded to splenectomy. This complication of TTP may become more common with improved survival in TTP. Recognition may prevent inappropriate therapy.