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Emergency and Acute Medicine – Leukemia
Basic description
Leukemia refers to a group of malignant neoplasms of white blood cells that result from uncontrolled proliferation of abnormal leukocytes. These malignant cells infiltrate the bone marrow and peripheral blood, impairing normal hematopoiesis. A dangerous complication is hyperleukocytosis, defined as a white blood cell count greater than 100,000/mm³, which can cause leukostasis with occlusion of small vessels, most commonly affecting the brain and lungs. Patients may present with confusion, stupor, hypoxia, or respiratory distress.
Classification and pathophysiology
Chronic myelogenous leukemia (CML) is characterized by overproduction of granulocytic white blood cells, primarily neutrophils, which typically retain normal function. Thrombocytosis and basophilia are common, and the Philadelphia chromosome is present in more than 95% of cases. Chronic lymphocytic leukemia (CLL), the most common leukemia in adults, involves overproduction of monoclonal lymphocytes that accumulate in lymph nodes, bone marrow, liver, and spleen, predisposing patients to herpes virus infections. Acute leukemias, including acute myelogenous leukemia (AML) and acute lymphocytic leukemia (ALL), involve rapid proliferation of immature blast cells and are rapidly fatal without treatment.
Etiology and risk factors
The exact cause of leukemia is unknown. Familial clustering is seen in CLL. Exposure to ionizing radiation increases the risk of AML, ALL, and CML. In pediatric patients, ALL is the most common leukemia and the most common childhood cancer, with remission rates of 60–80% in standard-risk patients. Prognosis is poorer in infants younger than one year. Pregnancy-associated leukemias are most often AML or ALL, and treatment should not be delayed despite potential fetal risks. Older adults more commonly present with CLL or CML.
Diagnosis: signs and symptoms
Clinical presentation varies by leukemia type. CML is often asymptomatic initially but may present with fatigue, weight loss, left upper quadrant pain from splenomegaly, and later leukostasis symptoms such as dyspnea, confusion, and drowsiness. CLL is frequently asymptomatic and discovered incidentally but may present with fatigue, weight loss, lymphadenopathy, hepatosplenomegaly, and recurrent infections. Acute leukemias present more dramatically with fever, fatigue, pallor, bone pain, bleeding due to thrombocytopenia, infections from neutropenia, and symptoms of organ infiltration. Leukemic meningitis may cause headache, nausea, seizures, and altered mental status.
Physical examination findings
Common findings include pallor, petechiae, purpura, ecchymoses, lymphadenopathy, hepatomegaly, and splenomegaly. Chloromas, or granulocytic sarcomas, may be seen in AML. Sausage-shaped hemorrhagic retinal veins are pathognomonic for hyperviscosity syndromes associated with hyperleukocytosis.
Essential workup
Initial evaluation includes a complete blood count with differential and platelet count. CML typically shows markedly elevated white blood cell counts with neutrophil predominance and thrombocytosis. CLL demonstrates absolute lymphocytosis, often greater than 5,000/mm³. Acute leukemias commonly show anemia, thrombocytopenia, and variable white blood cell counts. Bone marrow biopsy is required to confirm the diagnosis.
Diagnostic tests and interpretation
Laboratory studies should include electrolytes, renal function, glucose, calcium, uric acid, and lactate dehydrogenase, which is often elevated in acute leukemias. Coagulation studies are essential to evaluate for disseminated intravascular coagulation. Blood and urine cultures should be obtained in febrile patients. Imaging with chest radiography is useful in evaluating for infection or pulmonary leukostasis. Bone marrow biopsy findings distinguish leukemia subtypes, and cytogenetic testing identifies the Philadelphia chromosome in CML.
Differential diagnosis
The differential includes leukemoid reactions from infection, lymphoma, myeloproliferative disorders, autoimmune disease, viral infections such as Epstein–Barr virus, aplastic anemia, and other causes of cytopenias or lymphocytosis.
Initial stabilization and emergency management
Management begins with airway, breathing, and circulation stabilization. Supplemental oxygen is provided for hypoxia, and IV access is established with isotonic fluids. Platelet transfusions are indicated for significant bleeding, and packed red blood cells are given for symptomatic anemia. Febrile neutropenic patients require prompt broad-spectrum antibiotics. Disseminated intravascular coagulation should be treated aggressively if present.
Emergency department treatment
Leukostasis is treated with aggressive IV hydration, urine alkalinization, allopurinol or rasburicase to prevent tumor lysis syndrome, and urgent leukapheresis. Hydroxyurea is used for cytoreduction in CML. Corticosteroids or whole-brain radiation may be required for central nervous system involvement. Blood products may need to be irradiated or leukocyte-reduced. Definitive therapy, including chemotherapy, immunotherapy, or bone marrow transplantation, is initiated after hematology consultation.
Disposition and follow-up
Admission is required for most newly diagnosed patients, particularly those with symptomatic anemia, thrombocytopenia, hyperleukocytosis, or infection. ICU admission is indicated for unstable patients with bleeding, disseminated intravascular coagulation, blast crisis, or respiratory failure. Asymptomatic patients with minimal laboratory abnormalities may be considered for outpatient management only after hematology consultation.
Pearls and pitfalls
Hyperleukocytosis can present as respiratory failure or neurologic compromise and requires urgent treatment. Tumor lysis syndrome should be anticipated and prevented early. Do not delay hematology consultation in suspected leukemia, as early intervention significantly impacts outcomes.
Basic description
Leukemia refers to a group of malignant neoplasms of white blood cells that result from uncontrolled proliferation of abnormal leukocytes. These malignant cells infiltrate the bone marrow and peripheral blood, impairing normal hematopoiesis. A dangerous complication is hyperleukocytosis, defined as a white blood cell count greater than 100,000/mm³, which can cause leukostasis with occlusion of small vessels, most commonly affecting the brain and lungs. Patients may present with confusion, stupor, hypoxia, or respiratory distress.
Classification and pathophysiology
Chronic myelogenous leukemia (CML) is characterized by overproduction of granulocytic white blood cells, primarily neutrophils, which typically retain normal function. Thrombocytosis and basophilia are common, and the Philadelphia chromosome is present in more than 95% of cases. Chronic lymphocytic leukemia (CLL), the most common leukemia in adults, involves overproduction of monoclonal lymphocytes that accumulate in lymph nodes, bone marrow, liver, and spleen, predisposing patients to herpes virus infections. Acute leukemias, including acute myelogenous leukemia (AML) and acute lymphocytic leukemia (ALL), involve rapid proliferation of immature blast cells and are rapidly fatal without treatment.
Etiology and risk factors
The exact cause of leukemia is unknown. Familial clustering is seen in CLL. Exposure to ionizing radiation increases the risk of AML, ALL, and CML. In pediatric patients, ALL is the most common leukemia and the most common childhood cancer, with remission rates of 60–80% in standard-risk patients. Prognosis is poorer in infants younger than one year. Pregnancy-associated leukemias are most often AML or ALL, and treatment should not be delayed despite potential fetal risks. Older adults more commonly present with CLL or CML.
Diagnosis: signs and symptoms
Clinical presentation varies by leukemia type. CML is often asymptomatic initially but may present with fatigue, weight loss, left upper quadrant pain from splenomegaly, and later leukostasis symptoms such as dyspnea, confusion, and drowsiness. CLL is frequently asymptomatic and discovered incidentally but may present with fatigue, weight loss, lymphadenopathy, hepatosplenomegaly, and recurrent infections. Acute leukemias present more dramatically with fever, fatigue, pallor, bone pain, bleeding due to thrombocytopenia, infections from neutropenia, and symptoms of organ infiltration. Leukemic meningitis may cause headache, nausea, seizures, and altered mental status.
Physical examination findings
Common findings include pallor, petechiae, purpura, ecchymoses, lymphadenopathy, hepatomegaly, and splenomegaly. Chloromas, or granulocytic sarcomas, may be seen in AML. Sausage-shaped hemorrhagic retinal veins are pathognomonic for hyperviscosity syndromes associated with hyperleukocytosis.
Essential workup
Initial evaluation includes a complete blood count with differential and platelet count. CML typically shows markedly elevated white blood cell counts with neutrophil predominance and thrombocytosis. CLL demonstrates absolute lymphocytosis, often greater than 5,000/mm³. Acute leukemias commonly show anemia, thrombocytopenia, and variable white blood cell counts. Bone marrow biopsy is required to confirm the diagnosis.
Diagnostic tests and interpretation
Laboratory studies should include electrolytes, renal function, glucose, calcium, uric acid, and lactate dehydrogenase, which is often elevated in acute leukemias. Coagulation studies are essential to evaluate for disseminated intravascular coagulation. Blood and urine cultures should be obtained in febrile patients. Imaging with chest radiography is useful in evaluating for infection or pulmonary leukostasis. Bone marrow biopsy findings distinguish leukemia subtypes, and cytogenetic testing identifies the Philadelphia chromosome in CML.
Differential diagnosis
The differential includes leukemoid reactions from infection, lymphoma, myeloproliferative disorders, autoimmune disease, viral infections such as Epstein–Barr virus, aplastic anemia, and other causes of cytopenias or lymphocytosis.
Initial stabilization and emergency management
Management begins with airway, breathing, and circulation stabilization. Supplemental oxygen is provided for hypoxia, and IV access is established with isotonic fluids. Platelet transfusions are indicated for significant bleeding, and packed red blood cells are given for symptomatic anemia. Febrile neutropenic patients require prompt broad-spectrum antibiotics. Disseminated intravascular coagulation should be treated aggressively if present.
Emergency department treatment
Leukostasis is treated with aggressive IV hydration, urine alkalinization, allopurinol or rasburicase to prevent tumor lysis syndrome, and urgent leukapheresis. Hydroxyurea is used for cytoreduction in CML. Corticosteroids or whole-brain radiation may be required for central nervous system involvement. Blood products may need to be irradiated or leukocyte-reduced. Definitive therapy, including chemotherapy, immunotherapy, or bone marrow transplantation, is initiated after hematology consultation.
Disposition and follow-up
Admission is required for most newly diagnosed patients, particularly those with symptomatic anemia, thrombocytopenia, hyperleukocytosis, or infection. ICU admission is indicated for unstable patients with bleeding, disseminated intravascular coagulation, blast crisis, or respiratory failure. Asymptomatic patients with minimal laboratory abnormalities may be considered for outpatient management only after hematology consultation.
Pearls and pitfalls
Hyperleukocytosis can present as respiratory failure or neurologic compromise and requires urgent treatment. Tumor lysis syndrome should be anticipated and prevented early. Do not delay hematology consultation in suspected leukemia, as early intervention significantly impacts outcomes.
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