Prognostic factors of Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis in children: report of the Japan Histiocytosis Study Group.

Background: Despite several advances in the treatment of Epstein-Barr virus (EBV) in recent years, patients with Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis (EBV-HLH) do not always show satisfactory outcomes. We here conducted a nationwide survey in Japan to identify prognostic factors of EBV-HLH in children with this disease in an effort to improve the management and the outcomes of these patients.

Procedure: Between January 2003 and June 2008, we enrolled 98 children younger than 18 years of age who were diagnosed with EBV-HLH. We then studied the clinical characteristics and laboratory findings at the time of diagnosis with the aim to identify prognostic factors for EBV-HLH.

Results: The mean age of onset of EBV-HLH was 3.9 ± 2.8 years. Most of our patients presented with fever, hepatosplenomegaly, lymphadenopathy, and hemophagocytosis of bone marrow. Sixty-two percent of patients showed T cell clonality, and 97% had EBV infection in either T or natural killer cells. Most patients (60%) were treated with a multi-agent chemotherapeutic regimen, including corticosteroid, etoposide, and cyclosporine. After initial treatment, 90.3% of patients were in remission, and 7 patients (8.2%) experienced recurrence of EBV infection. Among several prognostic factors, patients with both hyperbilirubinemia (>1.8 mg/dl) and hyperferritinemia (>20,300 ng/ml) at the time of diagnosis had significantly poorer outcomes than those with low serum bilirubin and ferritin levels.

Conclusions: These findings suggest that the therapeutic strategy for children with EBV-HLH could be tailored according to the laboratory findings at diagnosis.