(aka Hyperleukocytic Syndrome)
Epidemiology
- Prevalence: occurs with WBC count >50-100k in the acute leukemias
Etiology
- Acute Myeloid Leukemia (AML) (see Acute Myeloid Leukemia): most common etiology
- CML (see Chronic Myeloid Leukemia): common etiology
- ALL (see Acute Lymphocytic Leukemia): very rare etiology
- CLL (see Chronic Lymphocytic Leukemia): occasional etiology
- All-Trans Retinoic Acid (ATRA) (see All-Trans Retinoic Acid)
- Used as therapy for APML
- May precipitate severe leukocytosis with resultant leukostasis
Physiology
- Occlusion of Pulmonary Capillaries by Leukemic Cells: forming plugs of aggregated blasts
- Typically occurs at WBC count >50-100k only
- Occurs more commonly in myeloid types due to less deformability of myeloblasts and monoblasts (as compared to lymphoblasts)
- Blood Viscosity: usually normal due to coexistent anemia (however, transfusion or diuresis may precipitate leukostasis in patients with severe leukocytosis)
Diagnosis
- CBC
- WBC count >200k: all patients have leukostasis by autopsy
- WBC count <50k: no patients have leukostasis by autopsy
Clinical
Pulmonary Manifestations
- Hypoxemia (see Hypoxemia): due to V/Q mismatch and/or acute lung injury-ARDS
- Diagnosis
- ABG: hypoxemia -> it is crucial to keep ABG on ice and process it quickly to avoid artifactual decrease in pO2 due to oxygen utilization by leukemic cells
- CXR/Chest CT: may be normal or have infiltrates, effusion, mediastinal lymphadenopathy
- Diagnosis
- Dyspnea (see Dyspnea)
- Diagnosis
- CXR/Chest CT: may be normal
- Diagnosis
- Acute Lung Injury-ARDS (see Acute Lung Injury-ARDS)
- Diagnosis
- CXR/Chest CT: lobar infiltrates, diffuse infiltrates, mediastinal lymphadenopathy
- Diagnosis
- Pleural Effuson (see Pleural Effusion-Exudate)
- Diagnosis
- Pleural Fluid: exudative, contains leukemic cells
- Diagnosis
- High-Risk of Pulmonary Thrombosis
Neurologic Manifestations
- Delirium/Altered Mental Status (see Delirium)
Cardiac Manifestations
- Myocardial Ischemia/Acute MI (see Coronary Artery Disease): due to coronary occlusion
Gastrointestinal Manifestations
- Intestinal Ischemia/Infarction (see Acute Mesenteric Ischemia)
Hematologic Manifestations
- Hypercoagulable State (see Hypercoagulable States)
Other Manifestations
- Fever (see Fever): may occur
Treatment
- Emergent Leukapheresis: may be useful, but studies suggest does not impact mortality
- Chemotherapy: may achieve response, but usually takes 2-3 days
- Chemo may precipitate acute lung injury (occurs within 48 hrs of starting) due to massive destruction of blasts
References
- Pulmonary leukostasis mimicking pulmonary embolism. Leukemia Research Volume 24, Issue 2 , Pages 175-178, February 2000