Acute myeloid leukemia in a young girl presenting with mediastinal granulocytic sarcoma invading pericardium and causing superior vena cava syndrome.

A 1-year-4-month-old girl who presented with pericardial effusion and superior vena cava (SVC) syndrome caused by a mediastinal mass was later proved to be a case of acute myeloid leukemia (AML) with mixed-lineage leukemia-gene translocation. The unusual presentation and the giant blasts with basophilic vacuolated cytoplasm had led to initial misdiagnosis of mediastinal lymphoma. She developed progressive SVC syndrome, unresolved pericardial effusion, and extensive leukemia cutis after initial induction therapy. She died soon after second-course chemotherapy. To our knowledge, this is the first reported case of childhood acute myeloid leukemia presenting with mediastinal granulocytic sarcoma causing pericardium invasion and SVC syndrome.