Sweet's syndrome in a patient with acute promyelocytic leukemia during treatment with all-trans retinoic acid.

A 53-year-old man with acute promyelocytic leukemia (APL) treated with all-trans retinoic acid (ATRA) developed fever and small erythemas on his arms and legs when the peripheral blood neutrophil count had increased. Erythemas gradually enlarged and painful subcutaneous nodules appeared. Skin biopsy revealed dense neutrophil infiltration in the dermis without vasculitis. These findings were compatible with Sweet's syndrome. Treatment with ATRA for APL was continued and no other additional therapy for Sweet's syndrome was performed. The syndrome was spontaneously improved in parallel with improvement of APL. In addition to this case report, three previously reported cases were reviewed to clarify the clinical characteristics of Sweet's syndrome in patients with APL during treatment with ATRA.