From the Guidelines
Pulmonary leukostasis in acute myeloid leukemia (AML) typically presents as acute respiratory distress with hypoxemia, dyspnea, tachypnea, and diffuse pulmonary infiltrates on chest imaging, and is a medical emergency requiring immediate cytoreduction and supportive care.
Clinical Presentation
Pulmonary leukostasis in AML often develops when the white blood cell count exceeds 100,000/μL, particularly with myeloblasts that are more rigid and adhesive than mature cells. Clinical manifestations include:
- Fever
- Cough
- Pleuritic chest pain
- Severe cases: hemoptysis Physical examination may reveal:
- Crackles
- Wheezing
- Decreased breath sounds Radiographic findings typically show:
- Bilateral interstitial or alveolar infiltrates
- Chest X-rays may initially appear normal Laboratory findings include:
- Severe hypoxemia on arterial blood gases
- Extremely elevated white blood cell count with predominant blasts
Pathophysiology and Management
The pathophysiology involves mechanical obstruction of pulmonary microvasculature by leukemic cells and release of inflammatory cytokines causing endothelial damage and increased vascular permeability, leading to the observed respiratory compromise 1. Management of pulmonary leukostasis requires:
- Immediate cytoreduction through hydroxyurea (2-3 g/day) and leukapheresis
- Initiation of chemotherapy
- Supportive care with oxygen, careful fluid management, and sometimes mechanical ventilation As noted in the guidelines for diagnosis, treatment, and follow-up of acute myeloblastic leukemia in adult patients, patients with excessive leukocytosis at presentation may require emergency leukapheresis prior to induction chemotherapy 1.
Key Considerations
It is essential to identify patients at risk of pulmonary leukostasis early and initiate prompt treatment to prevent morbidity and mortality. The use of anthracycline and cytarabine in induction chemotherapy is recommended, and haematopoietic growth factors may be considered as an optional adjunct to intensive induction chemotherapy 1. However, the primary focus should be on immediate cytoreduction and supportive care to manage the acute respiratory distress associated with pulmonary leukostasis.
From the Research
Presentation of Pulmonary Leukostasis in AML
Pulmonary leukostasis in Acute Myeloid Leukemia (AML) can present with severe respiratory impairment, as seen in a case report where a woman's debut of AML was characterized by severe respiratory impairment suspected to be pulmonary leukostasis, for which leukoapheresis was applied 2.
Clinical Manifestations
The clinical manifestations of leukostasis, including pulmonary leukostasis, are a result of the high concentrations of circulating leukemic cells, most often myeloblasts, which can lead to life-threatening complications 3.
Diagnosis and Management
Diagnosis of pulmonary leukostasis can be challenging, as it is often difficult to distinguish from other pulmonary complications 4. Management involves early recognition and treatment, with aggressive management of concurrent complications of the underlying leukemia 3.
Respiratory Events in AML
Respiratory events, including those caused by leukostasis, pulmonary leukemic infiltration, and acute lysis pneumopathy, are common in AML patients, with leukemia-specific respiratory events occurring in 61% of patients admitted to the ICU within 10 days of diagnosis 5.
Risk Factors and Treatment
Risk factors for death in patients with leukemia-specific respiratory events include age > 50, Eastern Cooperative Oncology Group (ECOG) status ≥ 2, and need for invasive mechanical ventilation, while dexamethasone therapy may be protective 5.
Pathophysiology
The pathophysiology of leukostasis involves the accumulation of leukemic cells in the microvasculature, leading to tissue hypoxia and organ dysfunction, with pulmonary leukostasis being a particularly severe manifestation 3.
Case Reports
Case reports, such as one involving a 65-year-old woman with acute monoblastic leukemia, highlight the importance of accurate diagnosis and timely treatment of pulmonary leukemic infiltration, which can be confirmed by transbronchial lung biopsy 4.