Sweet's syndrome during the treatment of acute promyelocytic leukemia with all-trans retinoic acid.

All-trans retinoic acid (ATRA) is the standard induction treatment for acute promyelocytic leukemia (APL). Quite many ATRA-related side effects, including retinoic acid syndrome, were reported. So far, it has rarely been reported that Sweet's syndrome, characterized by fever, neutrophilia, painful erythematous cutaneous plaques, dense dermal infiltrates of mature neutrophils and rapid response to steroid therapy, is associated with ATRA. In the case that Sweet's syndrome associated with ATRA is found, physicians will have to face a great challenge over the possibility of infectious conditions. We present here a case of Sweet's syndrome associated with ATRA. A 35-year-old female with APL developed fever, painful erythematous cutaneous plaques on both cheeks, right wrist and both shins during induction chemotherapy with ATRA. A skin biopsy revealed a dense dermal infiltrate, consisting of mature neutrophils without vasculitis or cutaneous immunoglobulin deposits, which is compatible with Sweet's syndrome. Oral prednisone was administered and the lesions started to improve within 48 hours.