Development of retinoic acid syndrome during leukopenia

We present a case involving a 53-year-old male with acute promyelocytic leukemia who developed retinoic acid syndrome (RAS) during leukopenia. He received all-trans retinoic acid (ATRA) therapy at a dose of 90 mg/day (45 mg/m²). On day 17, his fever increased to 38.1°C. As pain developed in his left ankle on day 19, ATRA was discontinued on day 20 because of the suspicion of an adverse reaction to the therapy such as RAS. On day 28, his fever increased markedly, and respiratory distress and bilateral pleural effusion developed. Although his maximum leukocyte count during the course of the condition was low (3,800/μl), steroid pulse therapy was started on day 32. Thereafter, these symptoms improved dramatically. Based on the clinical manifestations observed and the patient’s complete response to steroid pulse therapy, RAS was considered to have developed in the present case. RAS is associated with the development of hyperleukocytosis in most patients, but a few patients with normal leukocyte counts have developed the syndrome. As RAS is a fatal complication of ATRA therapy, early diagnosis and treatment are very important. The present case emphasizes the view that when administering ATRA, RAS should be kept in mind at all times.