Use of vincristine and cyclosporine in childhood thrombotic thrombocytopenic purpura.

Thrombotic thrombocytopenic purpura (TTP) is a rare but life-threatening hematologic disorder in children. Plasmapheresis, the standard therapy for TTP, is effective in achieving remission in most patients. However, some patients become either refractory to or dependent upon plasmapheresis. The authors report three such patients in whom the use of vincristine or vincristine plus cyclosporine resulted in permanent remission. A 12-year-old girl with TTP dependent on plasmapheresis for more than 5 months responded to vincristine with a decrease in the required frequency of plasmapheresis, but the addition of cyclosporine abrogated the need for further plasmapheresis. She subsequently developed serologic evidence of systemic lupus erythematosus. Two 15-year-old boys with TTP (one of them with underlying mixed connective tissue disease) became refractory to plasmapheresis after a brief initial response. The addition of vincristine in one patient and vincristine and cyclosporine in the second (with mixed connective tissue disease) led to complete remission. The authors' experience in this case study of three patients suggests that vincristine and cyclosporine are effective agents in the management of patients with TTP who do not achieve complete remission with plasmapheresis alone.