differentiation syndrome

A serious side effect that may occur in patients with acute promyelocytic leukemia or other types of acute myeloid leukemia who have been treated with certain types of anticancer drugs. Differentiation syndrome usually occurs within 1 to 2 weeks after starting treatment, but it can occur later. It is caused by a large, rapid release of cytokines (immune substances) from leukemia cells that are affected by the anticancer drugs. Signs and symptoms of differentiation syndrome include fever; cough; trouble breathing; weight gain; swelling of the arms, legs, and neck; build-up of excess fluid around the heart and lungs; low blood pressure; and kidney failure. Differentiation syndrome can be life-threatening if not treated early.