APL

Meaning of APL: APL is an aggressive subtype of acute myeloid leukemia marked by a specific chromosomal rearrangement and treated differently from other forms.

Definition of APL

APL, short for acute promyelocytic leukemia, is a subtype of acute myeloid leukemia in which immature blood forming cells called promyelocytes accumulate abnormally in the bone marrow and blood, crowding out the production of normal blood cells. It is considered an aggressive, fast growing leukemia that can progress quickly if not identified and treated.

APL is characterized by a specific rearrangement between chromosomes 15 and 17, which disrupts a gene involved in normal cell maturation and causes promyelocytes to accumulate instead of developing into mature white blood cells. Identifying this rearrangement is central to diagnosing APL and distinguishing it from other subtypes of acute myeloid leukemia.

Because this chromosomal change responds to specific targeted treatment not used for other forms of acute myeloid leukemia, correctly identifying APL is particularly important, and it is generally treated as a medical urgency due to its associated bleeding risk.