Retinoic acid syndrome in acute promyelocytic leukemia.

All-trans retinoic acid (ATRA) has been used successfully in inducing remission in patients with acute promyelocytic leukemia (APL). Its overall toxicity is considerably less compared to standard induction chemotherapy; however, it is associated with a high incidence of a potentially fatal symptom complex referred to as "retinoic acid syndrome." This report describes a patient with APL who developed the syndrome a few weeks after initiating induction therapy with ATRA despite being treated for hyperleukocytosis. The case illustrates the classic features of the syndrome and its dramatic response to corticosteroid treatment.