By Susha Cheriyedath, MSc
Acute promyelocytic leukemia (APL) is a subtype of acute myeloid leukemia (AML) and is characterized by a unique molecular abnormality. This sort of leukemia has actually a higher mortality fee and is associated along with early hemorrhagic death.
APL is relatively rare in adults and just 10-15% of adults diagnosed along with AML in the United States have actually APL. It is much more prevalent among kids along with AML and is mostly associated along with higher white blood cell (WBC) matter of >10,000/μL also as a greater lot of toxicities related to all-trans retinoic acid (ATRA), such as pseudotumor cerebri.
APL identification
APL is identified by the reciprocal translocation of chromosomes 15 and 17. The chromosome translocation triggers a fusion transcript to join the promyelocyte (PML) and retinoic acid receptor-α (RAR-α) genes. Leukemic PMLs can easily undergo differentiation on exposure to retinoic acid, while on exposure to arsenic trioxide they undergo differentiation also as apoptosis.
According to current recommendations, it is considered to be a medical emergency as soon as APL is suspected on the basis of blood smear morphology and/or clinical presentation. Along along with various other supportive measures such as platelet and cryoprecipitate administration, ATRA is administered without delay while awaiting genetic diagnosis.
Morphology
In APL patients, peripheral blood smear typically shows reasonable WBCs or leukopenia along with circulating PMLs. These cells have actually plenty of irregular primary azurophilic granules.
Leukemic PMLs having multiple Auer rods is located just in the case of APL. The nuclear contour has actually two lobes, though it is not clearly seen because of the presence of granules. The presence of numerous primary azurophilic granules could not confirm APL diagnosis since leukemic cells from patients along with various other AML subtypes could additionally have actually such granules.
Hematologists have to have actually a thorough discovering of these great morphologic details unique to APL as it needs prompt treatment as soon as suspected.
Management of APL
APL is treatable along with the advice of therapy targeted at the personal molecular abnormality. It is among the rather couple of malignant hematologic diseases that can easily be recognized by viewing the peripheral blood smear making use of a microscope.
Once APL diagnosis is suspected, ATRA is started free of waiting for confirmation of diagnosis by cytogenetic or molecular studies. A standard ATRA dose of 45 mg/m2 a day in several small doses is provided initially. This aids manage coagulopathy.
In reasonable risk patients (i.e., WBCs <10,000/μL), ATRA therapy is continued for a couple of days prior to chemotherapy is started. In the case of patients at higher risk (i.e., WBCs ≥10,000/μL), ATRA is combined along with chemotherapy also prior to confirmation of APL diagnosis. In all of cases of AML, no matter subtype, anthracycline is administered while awaiting genetic confirmation.
Early administration of ATRA combined along with blood product sustain has actually been revealed to lower mortality rates. The standard treatment currently used calls for anthracycline chemotherapy combined along with ATRA throughout induction and upkeep ATRA plus low-dose chemotherapy thereafter.
Newly diagnosed APL
In patients newly diagnosed along with APL, a much more efficient approach is to combine ATRA treatment along with arsenic trioxide. Chemotherapy can easily be continued minimally to maintain leukocytosis under control. This Brand-new approach could switch out traditional means in the future.
Anyone newly diagnosed along with AML need to be considered as a potential APL candidate, maintaining in thoughts that APL is various from various other subtypes and demands urgent and aggressive medical intervention.
Reviewed by Brandon May
