Recurrent thrombocytopenia following idiopathic thrombocytopenic purpura. The importance of platelet-bound IgG in establishing cause.

A 20-year-old man experienced two separate thrombocytopenic illnesses. The first episode represented classic idiopathic thrombocytopenic purpura (ITP) and was associated with elevated platelet-bound IgG values. Adequate control of thrombocytopenia could not be obtained with prednisone therapy, and splenectomy produced a clinical remission. Four weeks after splenectomy, an acute febrile illness typical of cytomegalovirus (CMV) infection developed, and CMV grew grom a sample of the patient's blood. Thrombocytopenia recurred during the CMV infection but was not associated with elevated platelet-bound IgG levels. Since the second episode of thrombocytopenia was associated with normal amounts of platelet-bound IgG, it was not ascribed to relapse of the ITP, and the thrombocytopenia resolved rapidly, without specific therapy. There are various therapeutic implications of an accurate causative diagnosis of thrombocytopenia.