Severe Symptoms of Hyperhistaminemia after the Treatment of Acute Promyelocytic Leukemia with Tretinoin (all-transRetinoic Acid)

RECENT reports that tretinoin (all-trans-retinoic acid) induced the maturation of leukemic cells in vivo and in vitro and yielded high rates of complete remission in patients with acute promyelocytic leukemia illustrate a form of therapy that induces the differentiation of leukemic cells rather than a cytotoxic effect.1 2 3 4 In this form of treatment, leukemic cells undergo terminal differentiation and lose the capacity to proliferate. The clinical response to tretinoin often includes an increase in the number of abnormal neutrophils, which is caused by the maturation of leukemic cells during the induction of remission. This beneficial effect can usually be . . .