INTRODUCTION {#sec1-1}
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Leukostasis, or the accumulation of leukocytes occupying the lumen, is a complication of acute myeloid leukemia which mainly affects the lung, although it can also affect the central nervous system.  This complication, on its own, is considered the worst prognosis factor and differential diagnosis should be made with infections, thromboembolism, or bleeding.\[[@ref1][@ref2]\]

CASE REPORT {#sec1-2}
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We report the case of a woman, 19 years old, admitted with duration of 30 days progressive dyspnea at rest, associated with afternoon fever and was needed the invasive mechanical ventilation, 12 hours after arrival at the hospital. 

Blood tests showed leukostasis of 369000 u/L with 81% blasts, hemoglobin of 2g/dL, platelets 30000 u/L. The chest X-ray showed adifuse alveolar-interstitial infiltrate \[[Figure 1a](#F1){ref-type="fig"}\].  By aspirate and bone marrow biopsy, diagnosis of acute myeloid leukemia MO (M0 through M7 are the subtypes of acute myeloid leukemia, based on the type of cell and M0 designates acute myeloid leukemia with minimal morphologic or cytochemical differentiation) of Franco American British (FAB) classification was confirmed.  Suspecting a pulmonary leukostasis, leukoapheresis was initiated (technique by which blood from a vein is removed, leukocytes are removed selectively, and the remaining blood is reinfused into the donor) in two sessions, 6 hours apart, blood transfusion and chemotherapy, reducing the leukocyte count to 18000 u/L at the fourth day of admission improving in the respiratory function, allowing to remove mechanical ventilation 4 days after admission \[[Figure 1b](#F1){ref-type="fig"}\]. 

![ The chest x ray show an alveolar-interstitial infiltrate in the four quadrants with bibasal dominance (Figure a).  After treatment showed an evident improvement of the infiltrates (Figure b)](IJCIIS-5-125-g001){#F1}

DISCUSSION {#sec1-3}
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5--13% of patients with acute myeloid leukemia have hyperleukostasis (\>50000 u/L) but its pathophysiological mechanism is still not completely clear.  There is probably a direct endothelial cell damage, which would explain the presence of pulmonary leukostasis in the absence of leucocytosis.\[[@ref3][@ref4]\]

There is no diagnostic test beyond the lung biopsy to help identify this disease; therefore, it takes a high level of clinical suspicion for the early onset of leukocytoreduction with leukapheresis and chemotherapy.\[[@ref5]\]

**Source of Support:** Nil

**Conflict of Interest:** None declared.