Retinoic acid syndrome induced by arsenic trioxide in treating recurrent all-trans retinoic acid resistant acute promyelocytic leukemia.

Arsenic Trioxide (As2O3) is an effective agent for treating acute promyelocytic leukemia achieving a complete remission rate of about 60% to 90%. It is similar to all-trans retinoic acid (ATRA) when treating acute promyelocytic leukemia (APL), because both agents have limited side effects compared to conventional chemotherapy, although the treatment period is more prolonged. During treatment, both agents may induce leukocytosis, and in patients taking ATRA, leukocytosis appears to be related to the development of retinoic acid syndrome (RAS). We report here a case of APL treated with ATRA in combination with chemotherapy 3 years earlier. During treatment, an episode of RAS with fever, edema, pericardiac effusion etc. was encountered. Recently, she had a relapse of leukemia, and As2O3 therapy was used. Leukocytosis developed again, and symptoms of fever, skin rash, edema resembling a RAS also developed, which was quickly relieved by steroid administration in a manner resembling response to RAS.