A case of acute promyelocytic leukemia showing transient thrombocytosis caused by increased interleukin-6 and thrombopoietin after treatment with all-trans retinoic acid and chemotherapy.

A patient with acute promyelocytic leukemia(APL)treated with all-trans retinoic acid(ATRA)and chemotherapy for remission induction developed marked thrombocytosis after bone marrow recovery. Thrombocytosis also occurred after post remission chemotherapies, although the degree of thrombocytosis gradually decreased. During thrombocytosis, plasma levels of interleukin-6(IL-6)were elevated while those of thrombopoietin(TPO)were not elevated. However, the plasma level of TPO was markedly elevated at the nadir after post remission chemotherapy. These findings suggest that in APL patients, thrombocytosis after treatment with ATRA and or chemotherapy may be caused by increased plasma levels of both of IL-6 and TPO.