Leukostasis and hyperleukocytosis


  • Hyperleukocytosis is lab abnormality of WBC >50-100K
  • Blood viscosity increases
  • Leukostasis is symptomatic hyperleukocytosis; it is a medical emergency
    • Most commonly seen with AML or CML in blast crisis
    • High blast cell count > WBC plugs in microvasculature
      • Brain and lung are most commonly affected
  • 20-40% of patients with leukostasis die within 1st week of presentation

Clinical Features

  • Fever
    • 80% of patients
    • May be due to inflammation associated with leukostasis or concurrent infection
  • Brain Leukostasis
  • Pulmonary Leukostasis
    • Respiratory distress
    • Hypoxemia
      • ABG may show falsely decreased PaO2; pulse oximetry is more accurate
    • Respiratory failure

Differential Diagnosis

Oncologic Emergencies



  • CBC
  • DIC labs
    • DIC occurs in up to 40% of patients
    • FDP, d-dimer, fibrinogen, coags
  • Tumor Lysis Syndrome labs
    • TLS occurs in up to 10% of patients
    • Chemistry
    • Uric acid
    • Calcium
    • Phosphate


  • High degree of suspicion needed to make the diagnosis
  • WBC count usually >100K; can have symptoms with WBC as low as 50K
  • CXR
    • Interstial or alveolar infiltrates


  • Hyperleukocytosis (asymptomatic)
  • Leukostasis
    • IV hydration
      • Prevent dehydration which can worsen condition
    • Chemotherapy
      • Only treatment proven to improve survival
    • Hydroxyurea + leukapheresis
      • Can be use for cytoreduction if chemo will be delayed
  • Allopurinol may help prevent Tumor lysis syndrome
  • Consider rasburicase
  • Broad spectrum antibiotics
    • The leading cause of death in blast crisis is infection (patients are functionally neutropenic)


  • Admit to ICU


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