Successful cyclosporine treatment for thrombocytopenia after salvage therapy with arsenic trioxide therapy followed by autologous hematopoietic stem cell transplantation in acute promyelocytic leukemia

A 55-year-old man with acute promyelocytic leukemia in the first relapse was treated with arsenic trioxide as salvage therapy. After obtaining molecular remission, he underwent autologous peripheral blood stem cell transplantation (PBSCT) with busulfan and melphalan conditioning. The transplant dose of CD 34-positive cells was sufficient, and engraftment was prompt. Platelet count increased to 320 x 10(9)/1 on day 21; however, it rapidly decreased to 27 x 10(9)/l on day 37. Despite treatment with corticosteroid, the platelet count decreased to 6 x 10(9)/l on day 55. About one month after cyclosporine administration, thrombocytopenia gradually improved. This clinical course suggests immune-mediated thrombocytopenia following autologous PBSCT.