ABSTRACT
BACKGROUND: Hemophagocytic lymphohistiocytosis(HLH) is a rare and fatal disorder in children. Recently its clinical characteristics and etiology of uncontrolled activation of cellular immune system in genetically predirected patients have keen elucidated. The authors analyzed the clinical characteristics and response to immunosuppressive agents of HLH patients in single institute. METHODS: The authors retrospectively analyzed various clinical data including CSF and bone marrow examination at diagnosis and follow up period in the 6 patients who were diagnosed as HLH at Asan Medical Center during last 2 years. Antithymocyte globulin(ATG : 10 mg/kg/day) and methylprednisolone(methyl-PD: 5 mg/kg/day) for 5 consecutive days as induction treatment and cyclosporin A(CsA) as maintenance treatment after induction with weekly intrathecal methotrexate for 5-6 weeks were given to the recently diagnosed 3 patients. RESULTS: All the patients except one were infants. Persistent fever, hepatosplenomegaly and pancytopenia were observed in all the patients. Family history of suspicious HLH was observed in 4 patients(67%). The characteristic elevated serum triglyceride(TG) level and/or decreased fibrinogen level were noted in all. Mild to moderate CSF pleocytosls with increased lymphocytes and monocytes was also observed in all during the disease course. Variable degree of nonqr-Langerhans cell histiocytic infiltration and hemophagocytosis were observed in all the cases. Of the 3 patients treated with ATG and methyl-PD, one achieved complete remission and the others achieved partial remission within 2 weeks of treatment, but all expired after 5 months, remission with CsA. Regardless of treatment regimen, all the 6 patients expired due to CNS sequelae of HLH. CONCLUSIONS: HLH mainly developed in infants. Persistant fever, hepatosplenomegaly and pancytopenia were observed in most cases with the characteristic change of serum TG and/or fibrinogen level. HLH should be included in the differential diagnosis in patients with these features especially when the family history of suspicious HLH is present, and histologic comfirmation of HLH could be easily accomplished with bone marrow study in most cases. Remission induction of HLH could be achieved with immunosuppressive treatment but it was difficult to maintain long term remission.