From the Guidelines
Acute Promyelocytic Leukemia (APL) typically presents with a combination of symptoms related to bone marrow failure and coagulopathy, including fatigue, weakness, pallor, frequent infections, and bleeding manifestations, with laboratory findings showing pancytopenia and abnormal promyelocytes in the peripheral blood and bone marrow. The symptoms of APL are primarily due to the bone marrow's inability to produce normal blood cells, leading to anemia, neutropenia, and thrombocytopenia. Patients may experience fatigue, weakness, and pallor due to anemia, as well as frequent infections from neutropenia. Bleeding manifestations, such as petechiae, ecchymoses, gingival bleeding, epistaxis, or menorrhagia, are common due to thrombocytopenia. The hallmark of APL is a severe coagulopathy resembling disseminated intravascular coagulation (DIC), which can cause life-threatening hemorrhage, particularly intracranial or pulmonary bleeding 1. Some key features of APL include:
- Pancytopenia with abnormal promyelocytes in the peripheral blood and bone marrow
- Distinctive bilobed nuclei and numerous azurophilic granules (Auer rods) in the promyelocytes
- Genetic characterization by the t(15;17) translocation, which creates the PML-RARA fusion gene
- Unique sensitivity to all-trans retinoic acid (ATRA) therapy, which can prevent fatal hemorrhagic complications if initiated promptly 1. It is essential to start ATRA immediately upon suspicion of APL, without waiting for genetic confirmation of the diagnosis, to prevent the lethal complication of bleeding 1. Monitoring for APL differentiation syndrome and coagulopathy is crucial, and patients should be followed closely for the development of leukemia-associated coagulopathy and hemorrhage at presentation and/or under induction 1.
From the Research
Presentation of Acute Promyelocytic Leukemia
Acute Promyelocytic Leukemia (APL) typically presents with distinct clinical and morphological features. The key characteristics of APL include:
- Leukopenia coexisting with a marrow replaced with granulated dysplastic promyelocytes 2
- Disseminated intravascular coagulopathy (DIC) 2, 3
- Lack of Ia (HLA-DR) antigen expression 2
- Translocation between the long arms of chromosomes 15 and 17 (t[15;17]) 2
- Bleeding tendency due to DIC 3, 4
- Presence of atypical promyelocytes 3
Clinical Features
Patients with APL often present with:
- Haemorrhagic diathesis 5
- Auer rods in the blasts 5
- Poor prognostic factors include older age, elevated white blood cell count, low platelet count, and CD56 expression 5
- High risk of early hemorrhagic death due to DIC and hyperfibrinolysis 4
Age and Prognosis
APL patients are generally younger than those with other subtypes of Acute Myeloid Leukemia (AML) 2. They have a 70% to 80% likelihood of entering remission and are thought to have a more favorable prognosis than other individuals with AML 2. The prognosis of APL has improved dramatically following the introduction of all-trans retinoic acid (ATRA) and its combination with anthracycline-based chemotherapy during induction and consolidation 4.