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For further information, see CMDT Part 15-29: Acute Leukemia
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Essentials of Diagnosis
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Symptoms, including fatigue, fever, and bleeding, are of short duration
Cytopenias or pancytopenia
Blasts in peripheral blood in 90% of cases
> 20% blasts in bone marrow
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General Considerations
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A malignancy of the hematopoietic progenitor cell; cells proliferate in uncontrolled fashion and replace normal bone marrow elements
Most cases arise with no clear cause
Radiation and some toxins (benzene) are leukemogenic; chemotherapeutic agents (cyclophosphamide, melphalan, other alkylating agents, and etoposide) may cause leukemia
Acute myeloid leukemia (AML) is primarily categorized based on recurrent structural chromosomal and molecular abnormalities
Acute promyelocytic leukemia (APL)
Acute lymphoblastic leukemia (ALL) is classified by immunologic phenotype as B- or T-cell lineage
Cytogenetics are single most important prognostic factor
Acute leukemia of ambiguous lineage (ALAL)
Consists of blasts that lack differentiation along the lymphoid or myeloid lineage or blasts that express both myeloid and lymphoid lineage-specific antigens
Considered very-high risk and has a poor prognosis
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ALL comprises 80% of acute leukemias of childhood; peak incidence is between ages 3 and 7 years
ALL is also seen in adults, causing ∼20% of adult acute leukemias
AML chiefly occurs in adults with median age at presentation of 60 years and increasing incidence with advanced age
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Clinical findings are due to replacement of normal bone marrow or infiltration of organs (skin, gastrointestinal tract, meninges)
Gingival bleeding, epistaxis, or menorrhagia common
Less commonly, widespread bleeding from disseminated intravascular coagulation (DIC) (in APL and monocytic leukemia)
Increased susceptibility to infection when neutrophil count < 500/mcL (0.5 × 109/L)
Death may occur within a few hours if treatment is delayed
Signs of infection may be absent
Common presentations include cellulitis, pneumonia, and perirectal infections
Fungal infections (eg, Candida, Aspergillus) are also commonly seen
Pallor, purpura, and petechiae are common
Hepatosplenomegaly and lymphadenopathy are variable
Bone tenderness, particularly of the sternum, tibia, and femur
Hyperleukocytosis
Seen in patients who complain of gum hypertrophy and bone and joint pain
Circulating blast count is markedly elevated (total white blood cell (WBC) count > 100,000/mcL [100 × 109/L])
Leads to impaired circulation, presenting as headache, confusion, and dyspnea
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Differential Diagnosis
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AML
ALL
Chronic lymphocytic leukemia
Small lymphocyte lymphoma
Hairy cell leukemia
Atypical lymphocytosis of mononucleosis or pertussis
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