Leukostasis, Infiltration and Pulmonary Lysis Syndrome Are the Three Patterns of Leukemic Pulmonary Infiltrates

Abstract

Noninfectious causes of pulmonary involvement in patients with hyperleukocytic leukemia include pulmonary leukostasis, leukemic pulmonary infiltration, and acute lysis pneumopathy. Leukostasis can be proven only by autopsy. Therefore, studies of leukostasis often consist of retrospective evaluations of causes of death in patients with advanced leukostasis. Although the data from these studies are useful, they may fail to help clinicians recognize leukostasis at a stage when treatment can prevent a fatal outcome. Studies of findings obtained by clinical examination, laboratory tests, chest X-ray, lung scans, and other methods failed to establish reproducible criteria for diagnosing leukostasis. In recent years, interesting data on the expression of numerous adhesion molecules have been reported for most of the subtypes of acute myeloid leukemia (AML). Supportive treatment seems to have improved survival in patients with pulmonary leukostasis. Leukapheresis has been suggested as a means of rapidly decreasing the leukocyte count before chemotherapy, but few data are available to support the efficacy of leukapheresis in improving early survival. Hydroxyurea at a dosage of 40–50 mg/kg/day may be more effective than leukapheresis. Recent insights into the pathophysiology of leukostasis suggest that corticosteroid therapy may hold promise for the management of leukostasis-related lung involvement. Lung infiltration by leukemic cells may occur early on or during relapses. None of the clinical or radiographic findings is specific. Distinguishing leukostasis and leukemic infiltration relies on the leukocyte count and, if available, histological data. Leukemic infiltrates also require urgent chemotherapy. Acute lysis pneumopathy occurs a few hours or days after chemotherapy initiation, chiefly in patients with hyperleukocytic leukemia. Histology often shows diffuse alveolar damage and hemorrhage suggesting endothelial lesions. Chemotherapy discontinuation may be useful, although supportive care, including aggressive blood transfusions, is the most important treatment. Leukostasis, leukemic lung infiltration, and acute lysis pneumopathy are often closely interrelated. The prognosis was good in the most recent case series, indicating that ICU admission is in order for patients with acute respiratory failure possibly due to leukostasis, leukemic infiltration, or acute lysis pneumopathy.