(aka Hyperleukocytic Syndrome)


  • Prevalence: occurs with WBC count >50-100k in the acute leukemias



  • 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)


  • CBC
    • WBC count >200k: all patients have leukostasis by autopsy
    • WBC count <50k: no patients have leukostasis by autopsy


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
  • Dyspnea (see Dyspnea)
    • Diagnosis
      • CXR/Chest CT: may be normal
  • Acute Lung Injury-ARDS (see Acute Lung Injury-ARDS)
    • Diagnosis
      • CXR/Chest CT: lobar infiltrates, diffuse infiltrates, mediastinal lymphadenopathy
  • Pleural Effuson (see Pleural Effusion-Exudate)
    • Diagnosis
      • Pleural Fluid: exudative, contains leukemic cells
  • High-Risk of Pulmonary Thrombosis

Neurologic Manifestations

  • Delirium/Altered Mental Status (see Delirium)

Cardiac Manifestations

Gastrointestinal Manifestations

Hematologic Manifestations

Other Manifestations

  • Fever (see Fever): may occur


  • 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


  • Pulmonary leukostasis mimicking pulmonary embolism. Leukemia Research Volume 24, Issue 2 , Pages 175-178, February 2000