From the Guidelines
No, acute promyelocytic leukemia (APL) and acute monocytic leukemia are not the same. They are distinct subtypes of acute myeloid leukemia (AML) with different cellular origins, genetic abnormalities, clinical presentations, and treatment approaches. APL, classified as AML-M3 in the French-American-British classification, is characterized by a specific genetic abnormality—the PML-RARA fusion gene resulting from the t(15;17) chromosomal translocation, as noted in the management guidelines for APL 1. This subtype is notable for its responsiveness to all-trans retinoic acid (ATRA) and arsenic trioxide (ATO), which can induce differentiation of leukemic promyelocytes. In contrast, acute monocytic leukemia (AML-M5) involves the proliferation of abnormal monocytes and their precursors. It lacks the PML-RARA fusion and requires conventional chemotherapy approaches. The distinction is crucial because APL represents a medical emergency due to its association with disseminated intravascular coagulation (DIC), but also has a more favorable prognosis when treated appropriately with ATRA-based regimens, as emphasized in guidelines for acute myeloid leukemia management 1.
Some key differences between APL and acute monocytic leukemia include:
- Genetic abnormalities: APL is characterized by the PML-RARA fusion gene, while acute monocytic leukemia does not have this specific genetic abnormality.
- Clinical presentation: APL often presents with symptoms related to disseminated intravascular coagulation (DIC), such as bleeding and thrombosis, whereas acute monocytic leukemia may present with symptoms related to monocytosis, such as gum infiltration and skin lesions.
- Treatment approaches: APL is treated with ATRA and ATO, which can induce differentiation of leukemic promyelocytes, while acute monocytic leukemia requires conventional chemotherapy approaches.
- Prognosis: APL has a more favorable prognosis when treated appropriately with ATRA-based regimens, while acute monocytic leukemia has a variable prognosis depending on several factors, including the presence of certain genetic abnormalities and the patient's response to chemotherapy.
Overall, the management of APL has been revolutionized by the introduction of ATRA and ATO, and early diagnosis and treatment are crucial to prevent complications and improve outcomes, as highlighted in recent expert panel recommendations 1.
From the Research
Definition and Classification
- Acute promyelocytic leukemia (APL) is a subtype of acute myeloid leukemia (AML) characterized by the accumulation of malignant promyelocytes in the bone marrow 2, 3, 4, 5.
- Acute monocytic leukemia, on the other hand, is a type of AML that involves the proliferation of monocytic cells 6.
Clinical Features and Treatment
- The clinical features of acute monocytic leukemia and APL can be similar, but they have distinct differences in terms of cytological and cytochemical characteristics 6, 3.
- APL is typically treated with all-trans retinoic acid (ATRA) and chemotherapy, while acute monocytic leukemia is treated with cytosine arabinoside, anthracyclines, and VP 16-213 6, 2, 4.
- Some cases of acute myeloid leukemia with monocytic differentiation can mimic APL clinically and laboratory-wise, but they require distinct treatment approaches 3.
Key Differences
- APL is characterized by a specific chromosomal translocation, t(15;17), which is not typically found in acute monocytic leukemia 3, 5.
- The treatment outcomes and prognosis of APL and acute monocytic leukemia also differ, with APL being highly curable with ATRA and chemotherapy 2, 4.
- The presence of specific gene translocations, such as KMT2A translocations, can help distinguish between APL and other types of leukemia, including acute monocytic leukemia 3.