APL leukemia is acute promyelocytic leukemia, also known as acute myeloid leukemia type m3. It is a special type of leukemia. Due to the formation of fusion genes on chromosomes 17 and 15, leukemia cells stop differentiating at the promyelocytic stage and promyelocytes proliferate in the bone marrow, resulting in a series of symptoms such as anemia, infection, and bleeding. Acute promyelocytic leukemia is currently the best type of leukemia to treat. In the past, with this type of leukemia, patients often died because of severe early bleeding and high mortality. However, in recent years, due to the discovery of retinoic acid and arsenious acid in China, which can be used in the treatment of acute promyelocytic leukemia, the prognosis of patients has significantly improved and most patients are able to be cured and it is also the type of leukemia that can be cured without bone marrow transplantation at present.