Abstract: | Approximately 10% of neonates with Down syndrome may develop a form of megakaryoblastic leukemia that usually disappear spontaneously during the first months of the life. Although it seems to have a benign course, it may also be lethal and severe in some cases, especially in the form of hydrops and/or cardiopulmonary failure. Herein, we report a male infant with Down syndrome who was admitted with respiratory distress due to severe pericardial effusion leading to pericardial tamponade in the first 2 weeks of life. Pericardiosentesis and pericardial tube replacement in combination with steroid therapy was performed. He responded well to these therapies and his leukemia resolved on the fourth month of life. This case suggests that severe pericardial effusion and pericardial tamponade may be life-threatening complications of transient leukemia of Down syndrome and also it may be managed successfully with appropriate treatments. |