1Department of Pediatrics, Graduate School of Medicine, Gachon University, Incheon, Korea.
2Department of Pathology, Graduate School of Medicine, Gachon University, Incheon, Korea.
A 1 5/12-year-old girl was admitted with persistent high fever accompanied by mild cough. Physical examination revealed moderate hepatomegaly and splenomegaly. Laboratory tests revealed bicytopenia (hemoglobin level, 10.5 g/dL; white blood cell count, 2.9×109/L; neutrophil count, 0.5×109/L; and platelet count, 14.0×109/L) and prolonged prothrombin time (16.4 sec [normal range, 9.5-13.0 sec]) and activated partial thromboplastin time (47.3 sec [normal range, 24.0-43.5 sec]) with hypofibrinogenemia (plasma fibrinogen level, 0.8 g/L). Blood chemistry results were as follows: aspartate aminotransferase, 2,347 U/L; alanine aminotransferase, 900 U/L; lactate dehydrogenase, 4,350 U/L; triglyceride, 157 mg/dL; and ferritin, >16,500 µg/L. Serology test results were negative for Epstein-Barr virus and cytomegalovirus, and results of genetic mutation associated with hemophagocytic lymphohistiocytosis (HLH) were also negative. Bone marrow findings were compatible with HLH (proliferation of histiocytes, approximately 50% showing hemophagocytosis;