Venoocclusive disease due to chemotherapy for pediatric acute lymphoblastic leukemia is associated with increased levels of plasminogen‐activator inhibitor‐1

We describe three cases of sinusoidal obstruction syndrome/venoocclusive disease (SOS) in pediatric patients with acute lymphoblastic leukemia (ALL). All three episodes occurred during or just after the induction or reinduction phase of treatment based on prednisone/dexamethasone, vincristine, daunorubicin, and pegylated‐l ‐asparaginase. SOS episodes were categorized as mild/moderate and resolved in 7, 10, and 16 days using supportive measures or defibrotide therapy. In all three episodes, the clinical diagnosis of SOS was associated with a significant increase in plasminogen‐activator inhibitor‐1 (PAI‐1) that reduced with patient clinical improvement. PAI‐1 warrants study as a diagnostic marker for SOS in ALL.