Retinoic acid syndrome: a review

The retinoic acid syndrome (RAS) is an unpredictable but frequent complication which may develop after administration of all-trans retinoic acid (ATRA) most commonly in patients with acute promyelocytic leukaemia (APL). In this review, we describe the incidence, predictive factors, clinical course, outcome and treatment of RAS in patients with APL treated with ATRA. The incidence of RAS in patients receiving ATRA is about 14-16%, with an associated mortality of about 2%. Initial high white blood cell (WBC) count, rapidly increasing WBC count and/or the presence of the CD 13 expression on leukaemic cells may help in identifying patients likely to develop RAS. Concurrent chemotherapy will probably decrease the risk of developing RAS but often exacerbates bleeding, leading to leucocytosis, thrombocytopenia, disseminated intravascular coagulation and fibrinolysis. Prophylactic steroids are not recommended but prompt administration of steroids at the first sign of unexplained dyspnea, fever, weight gain or pulmonary infiltrate, is critical. Liposomal ATRA is being investigated to induce haematological cure in APL without chemotherapy and to reduce the incidence of RAS but further validation of its usefulness is necessary.