Leukostasis1

Tissues Affected Signs and Symptoms Measurement
Pulmonary Dyspnea and hypoxia with or without diffuse interstitial or alveolar infiltrates Pulse oximetry
Neurological Visual changes, headache, dizziness, tinnitus, gait instability, confusion, somnolence, sometimes coma, increased risk of intracranial hemorrhage Brain imaging with noncontrasted CT or MRI
Systemic Fever occurs in 80% of patients due to inflammation or infection Infection cannot be easily excluded and should be treated empirically in all patients
Uncommon signs and symptoms Myocardial ischemia, right ventricular overload, worsening renal insufficiency, priapism, acute limb ischemia, bowel infarction Varies
  • Hyperleukocytosis is a laboratory abnormality that has been variably defined as a total leukemia blood cell count greater than 50 × 109/L (50,000/µL) or 100 × 109/L (100,000/µL)
  • Leukostasis (also called symptomatic hyperleukocytosis) is a medical emergency most commonly seen in patients with AML or CML in blast crisis. It is characterized by an extremely elevated blast cell count, white blood cell plugs in the microvasculature, and symptoms of decreased tissue perfusion
  • Leukostasis is typically diagnosed when an AML patient with hyperleukocytosis presents with respiratory or neurological distress
  • The incidence in newly diagnosed AML is between 10% and 20%
  • Prompt treatment is indicated since, if left untreated, the one-week mortality rate for leukostasis is approximately 20% to 40%
  • The pathophysiology is not fully understood, but two major theories exist:
    • Increased blood viscosity and impeded blood flow due to plugs formed from the large circulating population of rigid blasts
    • Decreased blood oxygen levels due to increased metabolic activity of dividing blasts
    • Likely that both mechanisms and possible unidentified mechanisms contribute
  • The main clinical symptoms and cause of early death are related to CNS (~40%) and lung involvement (~30%)
  • Less common signs and symptoms include:
    • Electrocardiographic signs of myocardial ischemia or right ventricular overload
    • Worsening renal insufficiency
    • Priapism
    • Acute limb ischemia
    • Bowel infarction
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Reference: 1. Schiffer CA. Hyperleukocytosis and leukostasis in hematologic malignancies. UpToDate website. https://www.uptodate.com/contents/hyperleukocytosis-and-leukostasis-in-hematologic-malignancies. Updated November 13, 2019. Accessed April 22, 2021.