Recurrent differentiation syndrome or septic shock? Unresolved dilemma in a patient with acute promyelocytic leukemia.

Differentiation syndrome (DS) is a life-threatening complication observed in patients with acute promyelocytic leukemia (APL) receiving induction therapy with all-trans-retinoic acid (ATRA). A bimodal incidence of DS has been observed, with a majority of cases occurring during the first week of ATRA treatment ("early" DS), but a substantial number of cases occurring during the third or even fourth week of ATRA treatment ("late" DS). However, to our knowledge occurrence of both early and late DS in the same patient has not been reported. We report an APL patient treated with the AIDA regimen, who experienced both early and late DS, a situation where differential diagnosis was difficult.