Acute Promyelocytic Leukemia (APL) is a sub-type of Acute Non Lymphoblastic Leukemia (ANLL) (see this term) classified as variant M3 under the French-American-British (FAB) classification. It represents 5-15% of ANLL occurring in children. Symptoms are non-specific, being similar to those of other ANLL sub-types (fever, malaise, palor, hemorrhages). However patients are at a higher bleeding risk, caused by a severe thrombocytopenia which results from reduced medullar production and increased consumption. This increased consumption is due to the release of the granular content of promyelocytes and laboratory tests disclose signs of disseminated intravascular coagulation. Promyelocytic blast cells are characterized by a specific reciprocal translocation between chromosomes 15 and 17 t(15;17), which results in the fusion of a truncated retinoic acid receptor-alpha (RAR-alpha) gene to a transcription unit called PML (for promyelocytic leukemia). The fused gene encodes an abnormal retinoic acid receptor, wich impairs the differentiation of promyelocytes . APL can be cured in more than 90% of patients with trans-retinoic acid (ATRA) that has been demonstrated to induce maturation of leukemic cells. Treatment consists of the combination of chemotherapy (mainly antracyclines) with ATRA as well as supportive care.
Last update: November 2003