Leukostasis and hyperleukocytosis

Background

• 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
  • Headache
  • Dizziness
  • Tinnitus
  • Visual disturbances
  • Ataxia
  • Confusion
  • Stupor
  • Coma
  • Sudden death
• Pulmonary Leukostasis
  • Respiratory distress
  • Hypoxemia
    • ABG may show falsely decreased PaO2; pulse oximetry is more accurate
  • Respiratory failure

Differential Diagnosis

Oncologic Emergencies

Related to Local Tumor Effects

• Malignant airway obstruction
• Bone metastases and pathologic fractures
• Malignant spinal cord compression
• Malignant Pericardial Effusion and Tamponade
• Superior vena cava syndrome

Related to Biochemical Derangement

• Hypercalcemia of malignancy
• Hyponatremia due to SIADH
• Adrenal insufficiency
• Tumor lysis syndrome
• Carcinoid syndrome

Related to Hematologic Derangement

• Neutropenic fever
  • Neutropenic enterocolitis (typhlitis)
• Leukostasis and hyperleukocytosis
• Hyperviscosity syndrome
• Thromboembolism

Related to Therapy

• Chemotherapy-induced nausea and vomiting
• Cytokine release syndrome
• Chemotherapeutic drug extravasation
• Differentiation syndrome (retinoic acid syndrome) in APML
• Stem cell transplant complications
• Catheter-related complications
  • Tunnel infection
  • Exit site infection
  • CVC obstruction (intraluminal or catheter tip thrombosis)
  • Catheter-related venous thrombosis
  • Fracture of catheter lumen
  • Oncologic therapy related adverse events

Evaluation

Work-Up

• 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

Evaluation

• 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

Management

• Hyperleukocytosis (asymptomatic)
  • Hydroxyurea may be all that is required
• 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)

Disposition

• Admit to ICU