Chief Corner: AML
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Acute Myeloid Leukemia
Acute myeloid leukemia (AML) is a collection of heterogeneous hematopoietic stem cell disorders characterized by incomplete maturation of blood cells and reduced production of normal hematopoietic elements. Greater than half of AML cases are in patients ≥ 65 years old. Likely risk factors include exposure to ionizing radiation, drugs that cause DNA damage (ie alkylating agents), and myelodysplastic processes or chronic bone marrow stem cells disorders. Common symptoms result from pancytopenia and include fatigue, dyspnea, infection, and bleeding.
Typical physical exam findings
- Lymphadenopathy
- Sternal tenderness
- Hepatosplenomegaly
- Gingival hyperplasia in monocytic variant
- Petechiae due to thrombocytopenia
- Leukemia cutis
- Leukostasis (confusion, dyspnea, and fever, especially if blast count > 100,000 per mcL)
Laboratory testing
- CBC and peripheral smear
- CMP
- Uric acid
- Magnesium
- Phosphate
- Coagulation studies
1) ≥ 20% blasts in blood or marrow
2) Select cytogenetic abnormalities (regardless of blast percentag
3) Myeloid sarcoma (regardless of blast percentage)
Treatment
the therapeutic strategy in patients with AML includes assessment to determine whether a patient is eligible for intensive induction chemotherapy. For AML, continuous-infusion cytarabine with an anthracycline remains the mainstay of induction therapy. Response assessment is typically performed after postinduction therapy and hematologic recovery, and is based on cytogenetics and molecular studies.
Acute Promyelocytic Leukoemia (APL) is an aggressive subtype of AML with a distinct cellular morphology and clinical presentation that may be associated with early death due to potentially fatal coagulopathy – namely DIC. APL comprises 10% of AML diagnoses, presents at median age 44 years, and may arise de novo or as the result of chemotherapy. The characteristic fusion gene PML-RARA produces a protein that suppresses signaling by all-trans retinoic acid, preventing differentiation of myeloid cells. When APL is first suspected, treat the disease as a medical emergency and initiate all-trans retinoic acid (ATRA) immediately. Diagnostic confirmation is by molecular detection of PML-RARA fusion after starting empiric therapy. For induction therapy, offer ATRA plus anthracycline-based chemotherapy, unless the patient is unable to tolerate anthracyclines or patient has low or intermediate risk disease.
Authored by: JAVIER BAEZ, MD
