The Outcome of 129 Korean Children with Hemophagocytic Lymphohistiocytosis.

Chemotherapy and immunotherapy based treatments improved survival of patients with hemophagocytic lymphohistiocytosis(HLH), but the outcome is still unsatisfactory. We analyzed the putative prognostic factors in a nationwide cohort of patients with HLH. Retrospective data recruitment for the patients diagnosed as HLH during the past 10-year period from 1996 to 2005 was carried out by the Histiocytosis Working Party of the Korean Society of Hematology. The HLH diagnostic criteria of the Histiocyte Society were strictly applied to confirm the eligibility of patients for this study. We analyzed the outcome of pediatric patients with HLH according to the age at diagnosis, sex, central nervous system(CNS) involvement, disease condition(familial or secondary), treatment modalities and disease state after 2 months of initial treatment. One hundred twenty nine patients from 19 centers fulfilled the diagnostic criteria(n=112) and/or had affected siblings together with some of the criteria(n=17). The male to female ratio was 0.95:1. The probability of 3 year overall survival(OS) in HLH patients was 41% with a median follow-up of 51 months. The 3 year OS in patients under 12 months of age at presentation(n=23) was 21.7%, and 44.3% in those over 12 months of age(n=106)(p=0.001). The 3 year OS in patients with CNS involvement(n=16) was 29.1%, and 44.4% in patients without CNS involvement(n=112)(p=0.01). The 3 year OS in patients with active state after 2 months of initial treatment(n=63) was 14.1% compared to 77.2% in those with inactive state(n=61)(p=0.0001). The 3 year OS in patients who received hematopoietic stem cell transplantation(HSCT)(n=17) was 82.3%, and 35.2% in patients treated with chemoimmunotherapy only(n=112)(p=0.03). Among the HSCT patients, complete remission was obtained in 14 patients except 3 other patients who died of infection and graft failure at early post-transplant period. The reasons for HSCT were active disease after chemoimmunotherapy(n=8), relapsed disease(n=5), and familial HLH(n=4). Other prognostic factors were not significantly correlated with outcome in our survey. The age and CNS involvement at diagnosis, disease state after 2 months of initial treatment were important prognostic factors which affected the outcome of HLH significantly in this cohort. This survey also demonstrated excellent outcome of familial or relapsed, persistent secondary HLH after HSCT compared to chemoimmunotherapy only.