Leukemia, Acute Myeloid (AML)

Key Features

• Approximately 500 new cases occur per year in children and adolescents in the United States

• Although AML accounts for only 25% of all leukemias in this age group, it is responsible for at least one-third of deaths from leukemia in children and teenagers

• Congenital conditions associated with an increased risk of AML include

  • Diamond-Blackfan anemia

  • Neurofibromatosis

  • Down syndrome

  • Wiskott-Aldrich, Kostmann

  • Li-Fraumeni syndromes

  • Chromosomal instability syndromes such as Fanconi anemia

• Acquired risk factors include exposure to ionizing radiation, cytotoxic chemotherapeutic agents, and benzenes

• However, the vast majority of patients have no identifiable risk factors

Clinical Findings

• Clinical manifestations commonly include anemia (44%), thrombocytopenia (33%), and neutropenia (69%)

• Symptoms may be few and innocuous or may be life threatening

• Hyperleukocytosis may be associated with life-threatening complications

• Venous stasis and sludging of blasts in small vessels cause hypoxia, hemorrhage, and infarction, most notably in the lung and CNS; this is a medical emergency requiring rapid intervention, such as leukophoresis, to decrease the leukocyte count

Diagnosis

• Median hemoglobin value at diagnosis is 7 g/dL

• Platelets usually number less than 50,000/μL

• Frequently the absolute neutrophil count is under 1000/μL, although the total WBC count is over 100,000/μL in 25% of patients

Treatment

• AML is less responsive to treatment than ALL and requires more intensive chemotherapy

• AML protocols rely on intensive administration of anthracyclines, cytarabine, and etoposide for induction of remission

• After remission is obtained,

  • Patients who have a matched sibling donor undergo allogeneic hematopoietic stem cell transplantation,

  • Patients without an appropriate related donor are treated with additional cycles of aggressive chemotherapy for a total of four to five cycles

• When WBC cell count is > 100,000/μL or significant adenopathy or organomegaly is present

  • Maintain brisk urinary output

  • Serum levels of potassium, phosphorus, and uric acid should be monitored

• Prompt initiation of broad-spectrum intravenous antibiotics when fever (temperature ≥ 38.3°C) or chills associated with and neutropenia develop during treatment

• Patients nonimmune to varicella

  • Should receive varicella-zoster immune globulin within 72 hours after exposure

  • Should be given intravenous acyclovir for active infection

• Pneumocystis prophylaxis must be administered during treatment and for several weeks afterward

• Hyperleukocytosis (WBC > 100,000/μL)

  • Medical emergency

  • Requires rapid intervention such as leukophoresis to rapidly decrease the number of circulating blasts and thereby decrease hyperviscosity

• Filgrastim (granulocyte colony-stimulating factor)

  • May be used to stimulate granulocyte recovery during the treatment of AML

  • Results in shorter periods of neutropenia and hospitalization